Dataset Viewer
text
stringlengths 145
7.65M
|
|---|
Cnc25D Documentation
Release 0.1.11
charlyoleg
October 08, 2016
Contents
1 Cnc25D Presentation 3
1.1 Cnc25D Python package content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Cnc25D Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Cnc25D Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5 License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.6 Feedback and contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.7 Releases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2 Cnc25D Release Notes 9
2.1 Release 0.1.11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Release 0.1.10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Release 0.1.9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Release 0.1.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.5 Release 0.1.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.6 Release 0.1.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.7 Release 0.1.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.8 Release 0.1.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.9 Release 0.1.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.10 Release 0.1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.11 Release 0.1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.12 Release 0.1.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3 Cnc25D API Overview 13
3.1 Cnc25D Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Cnc25D API functions and class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Cnc25D API Outline Creation 17
4.1 Cnc25D outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 Cnc25D outline format A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3 Cnc25D outline format B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.4 Cnc25D outline format C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.5 The function Cnc_cut_outline() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.6 The function smooth_outline_c_curve() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.7 The function smooth_outline_b_curve() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.8 Other outline help functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.9 ideal_outline() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
i
5 CNC Cut Outline Details 31
5.1 Introduction to the automated cutting technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2 2D path constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.3 Coplanar fitting details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.4 Incoplanar fitting details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6 Smooth Outline Curve Details 41
6.1 1. Curve approximation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.2 2. Double-arc solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7 Cnc25D API Outline Utilization 45
7.1 Transformations at the figure-level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.2 Display a figure in a GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.3 Write a figure in a SVF file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.4 Write a figure in a DXF file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.5 Extrude a figure using FreeCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.6 Detailed transformations at the outline-level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8 Cnc25D API Working with FreeCAD 49
8.1 import FreeCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.2 place_plank() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.3 Drawing export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9 Plank Positioning Details 53
9.1 Plank definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.2 Plank reference frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.3 Plank flip possibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9.4 Plank orientation possibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
9.5 Plank position in a cuboid construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
10 Cnc25D Internals 59
10.1 File layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
10.2 Design example generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
10.3 Python package distribution release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
10.4 Documentation process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
11 Creating a Cnc25D Design 65
11.1 Design Script Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
11.2 Design Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
11.3 Design Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
11.4 Design Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
11.5 Internal Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
12 Cnc25D Designs 75
12.1 Cnc25D design introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
12.2 Cnc25D design list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
12.3 Cnc25D design overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
13 Cnc25D Design Details 87
13.1 Cnc25D design usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
13.2 Cnc25D design implementation structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
14 Box Wood Frame Design 93
14.1 Box wood frame presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
14.2 Box wood frame creation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
ii
14.3 Box wood frame parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
14.4 Box wood frame conception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
14.5 Box wood frame manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
15 Box Wood Frame Conception Details 117
15.1 Design purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
15.2 Construction method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
15.3 Design proposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
15.4 Box wood frame parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
15.5 Plank outline description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
15.6 Diagonal plank reorientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
15.7 Slab outline description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
16 Gear Profile Function 131
16.1 Gear high-level parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
16.2 gear_profile() function arguments list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
16.3 From gear_profile() arguments to high-level parameters . . . . . . . . . . . . . . . . . . . . . . . . 139
16.4 Complement on gear high-level parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
17 Gear Guidelines 143
17.1 Strength and deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
17.2 Gear module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
18 Gear Profile Theory 145
18.1 Transmission per adhesion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
18.2 Transmission with teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
18.3 Tooth profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
18.4 Gear profile construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
18.5 Gear rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
18.6 Torque transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
18.7 Gearwheel position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
19 Gear Profile Details 163
19.1 Involute of circle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
19.2 Gear outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
19.3 Gear position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
20 Gear Profile Implementation 183
20.1 Internal data-flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
21 Gearwheel Design 185
21.1 Gearwheel Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
21.2 Gearwheel Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
22 Gearring Design 191
22.1 Gearring Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
22.2 Gearring Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
23 Gearbar Design 199
23.1 Gearbar Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
23.2 Gearbar Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
24 Split-gearwheel Design 203
24.1 Split-gearwheel Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
24.2 Split-gearwheel Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
iii
25 Epicyclic Gearing Design 207
25.1 Epicyclic Gearing Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
25.2 Epicyclic Gearring Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
25.3 Epicyclic Gearing Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
26 Epicyclic Gearing Details 221
27 Axle Lid Design 225
27.1 Axle-lid Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
27.2 Axle-lid Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
28 Axle_lid Details 233
29 Motor Lid Design 237
29.1 Motor-lid Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
30 Bell Design 245
30.1 Bell Parts and Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
30.2 Bell Parameter List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
30.3 Bell Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
31 Bell Details 259
32 Bagel Design 263
32.1 Bagel Parts and Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
32.2 Bagel Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
33 Bell Bagel Assembly 267
33.1 Bell-Bagel-Assembly Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
33.2 Bell-Bagel-Assembly Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
34 Crest Design 271
34.1 Crest Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
34.2 Crest Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
35 Cross_Cube Design 277
35.1 Cross_Cube Parts and Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
35.2 Cross_Cube Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
36 Gimbal Design 287
36.1 Gimbal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
36.2 Gimbal Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
37 Gimbal Details 293
37.1 Roll-Pitch angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
38 Planet_Carrier Design 301
38.1 Planet_Carrier Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
38.2 Planet_Carrier Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
39 Low_torque_transmission Design 307
39.1 Low_torque_transmission Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
39.2 Low_torque_transmission Parameter Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
40 Low_torque_transmission Details 317
41 High_torque_transmission Design 319
iv
42 Indices and tables 321
v
vi
Cnc25D Documentation, Release 0.1.11
Contents:
Contents 1
Cnc25D Documentation, Release 0.1.11
2 Contents
CHAPTER 1
Cnc25D Presentation
Cnc25D is the contraction of “CNC” and “2.5D”.
2.5D and cuboid assembly are good solutions for automated personal fabrication. The Python package cnc25d pro-
poses an API and design examples related to those technologies.
• CNC (Computer Numerical Control) and 3D-printers let move from design files to the physical objects.
• 2.5D parts are objects that can be described as a pile of free 2D path linearly extruded along the third dimension.
• Cuboid assembly is any assembly emphasizing an orthogonal reference frame.
1.1 Cnc25D Python package content
1.1.1 Generic functions
In the Cnc25D Python package, you find functions that help you design parts to be made by a 3-axis CNC, to assemble
those parts and to create DXF 2D plans of your design. In particular you get those functions:
•cnc_cut_outline takes as input a 2D polygon defined by a list of points and a CNC router_bit diameter and
provides as output a millable 2D outline. Then, you just need to extrude this outline to get your 2.5D part.
•place_plank offers an alternative natural way to place a part in a cuboid assembly.
3
Cnc25D Documentation, Release 0.1.11
•export_to_dxf writes a DXF file with a projection of a cut of your design.
•export_xyz_to_dxf writes a DXF file with many projections of cuts of your design along the 3 axis, in a similar
way as a medical 3D scanner.
DXF is 2D and is the most common design exchange file format. Usually, your CNC guy will need this file format to
start his process flow. You can use LibreCAD to view and possibly to re-work your DXF files.
You can also output your design in the 3D STL format and use MeshLab to view and inspect your parts and design.
1.1.2 Design examples
The Cnc25D Python package comes also with some design examples, which are probably for most of the users the
most useful things.
One good thing with Designing with Python script is that you get a 100% open-hardware design because all conception
micro-steps are pieces of code and can be shared and hacked using the tools of the software development such as git.
An other advantage of Designing with Python is that parametric design is natural. So you don’t create an object but a
family of objects with a set of parameters that individualize each manufactured object.
Designing with Python let you work in a similar way as software development. You write code, check the 3D result
with the FreeCAD GUI, modify and expand the code and so on. This iterative work-flow is very efficient to capitalize
work, reduce repetitive tasks, keep modification history, track bugs and co-work with people.
The complete list of Cnc25D Design is available in the section Cnc25D Designs.
Some realizations designed with Cnc25D :
• https://cubehero.com/physibles/charlyoleg/Box_Wood_Frame_N1
• https://cubehero.com/physibles/charlyoleg/Epicyclic_gearing_with_laser_cutter
• https://cubehero.com/physibles/charlyoleg/Epicyclic_gearing_with_3D_printer
1.2 Cnc25D Installation
The installation instructions are written for the Ubuntu systems.
1.2.1 Install Cnc25D on your system
This is the preferred method for most people.
• First, install FreeCAD (version 0.13 or newer), Python 2 and Tkinter (which is automatically installed with
Python on Ubuntu).
• Then, install the Cnc25D package with the following commands. (The second command is because of a bug in
the matplotlib dependency setup):
> sudo pip install Cnc25D -U
> sudo pip install matplotlib -U
• To create an design example, run the following commands:
> cd directory/where/I/want/to/create/my/3D/parts
> cnc25d_example_generator.py
> python box_wood_frame_example.py
4 Chapter 1. Cnc25D Presentation
Cnc25D Documentation, Release 0.1.11
1.2.2 Install Cnc25D in a virtual environment
This method has currently some issues because of PyQt4.
• First, install FreeCAD on your system (not in a virtual environment ). You need the version 0.13 or newer.
• Then, create the virtual environment and install the Cnc25D package within it:
> cd directory/where/I/want/to/work
> virtualenv env_for_cnc25d
> source env_for_cnc25d/bin/activate
> pip install Cnc25D -U
> pip install matplotlib -U
> deactive
• Workaround for PyQt4:
> cp /usr/lib/python2.7/dist-packages/sip.so env_for_cnc25d/lib/python2.7/site-packages/
> cp -a /usr/lib/python2.7/dist-packages/PyQt4 env_for_cnc25d/lib/python2.7/site-packages/
• To create an design example, run the following commands:
> source env_for_cnc25d/bin/activate
> cnc25d_example_generator.py
> python box_wood_frame_example.py
> deactivate
• You can also run the generated design example with freecad . But freecad doesn’t get the virtualenv python
package path and doesn’t read the environment variable PYTHONPATH . So, you must add the path to the
virtual python package explicitly:
> source env_for_cnc25d/bin/activate
> freecad -P env_for_cnc25d/lib/python2.7/site-packages box_wood_frame_example.py
> deactivate
1.2.3 Work directly with the Cnc25D sources
Instead of installing the Cnc25D package, you clone the Cnc25D GitHub repository and work directly with it. This is
the preferred method for the programmers:
> cd directory/where/I/want/to/work
> git clone https://github.com/charlyoleg/Cnc25D
Example of usage:
> cd Cnc25D/cnc25d
> python box_wood_frame.py
1.3 Cnc25D Usage
1.3.1 Use a design example
After installing Cnc25D, you get the executable cnc25d_example_generator.py . When you run this script, it asks
you for each design example if you want to generate the script example. Answer ‘y’ or ‘yes’ if you want to get the
script example. cnc25d_example_generator.py can generates the following Python script examples:
•box_wood_frame_example.py : The piece of furniture to pile up.
1.3. Cnc25D Usage 5
Cnc25D Documentation, Release 0.1.11
•cnc25d_api_example.py : This is not a design example, this shows how to use the API.
These scripts are the design examples. Edit one of these scripts, modify the parameter values, run the script. You get
plenty of DXF and STL, that you can view with LibreCAD and MeshLab. You also get a txt file, that provides you a
kind of report of your design. In summary, we run the following commands:
> cd directory/where/I/want/to/create/my/3D/parts
> cnc25d_example_generator.py
> vim box_wood_frame_example.py
> python box_wood_frame_example.py
> librecad bwf37_assembly_with_amplified_cut.dxf
> meshlab # import bwf36_assembly_with_amplified_cut.stl
> less bwf49_text_report.txt
This documentation contains one chapter per design examples that explains in particulary the parameter list.
1.3.2 Use a design example within FreeCAD
In the upper method, we have modified the design example script and then run it to get all the final design files. Even
if we can iterate this method, this can be tedious as the generation of all the files requires time. So, probably we want
to change a parameter value and just check the 3D result of the assembly. For this purpose, we use FreeCAD directly
with one of those three methods:
Script as FreeCAD argument
Launch FreeCAD as following:
> freecad box_wood_frame_example.py
The design appear in the main windows. Rotate and zoom on your design to inspect it and make sure it is as you want
it.
Script as FreeCAD macro
Launch FreeCAD and run the design example script from the macro menu:
FreeCAD Top Menu Macro > Macros ...
Within the pop-up window,
in the field *Macro destination *, select the directory where is located your *design example script *.
in the field *Macro name *, select your *design example script *.
click on *Execute*
Script run from FreeCAD
Launch FreeCAD and run the design example script from the Python console:
Launch FreeCAD from the directory where is located your *design example script *.
> cd directory/where/I/want/to/create/my/3D/parts
> freecad
Enable 'FreeCAD Top Menu View' > Views > 'Python Console'
Within the FreeCAD Python console, type:
> execfile("box_wood_frame_example.py")
6 Chapter 1. Cnc25D Presentation
Cnc25D Documentation, Release 0.1.11
1.3.3 Make your design script
If you are interested in the Cnc25D API and want to create your own design with, create a Python script with the
following snippet:
# import the FreeCAD library
from cnc25d import cnc25d_api
cnc25d_api.importing_freecad()
import Part
from FreeCAD import Base
# use the cnc_cut_outline function
my_polygon = [
[ 0, 0, 5],
[ 40, 0, 5],
[ 40, 40, 5],
[ 0, 40, 5]]
my_part_face = Part.Face(Part.Wire(cnc25d_api.cnc_cut_outline(my_part_outline).Edges))
my_part_solid = my_part_face.extrude(Base.Vector(0,0,20))
# use the place_plank function
my_part_a = cnc25d_api.place_plank(my_part_solid.copy(), 40, 40, 20, 'i', 'xz', 0, 0, 0)
# export your design as DXF
cnc25d_api.export_to_dxf(my_part_solid, Base.Vector(0,0,1), 1.0, "my_part.dxf")
xy_slice_list = [ 0.1+4 *iforiinrange(9) ]
xz_slice_list = [ 0.1+4 *iforiinrange(9) ]
yz_slice_list = [ 0.1+2 *iforiinrange(9) ]
cnc25d_api.export_xyz_to_dxf(my_part_solid, 40, 40, 20, xy_slice_list, xz_slice_list, yz_slice_list, "my_part_scanned.dxf")
Further documentation at Cnc25D API Overview . Also look at the script example cnc25d_api_example.py that you
can generate with the executable cnc25d_example_generator.py .
1.4 Links
1.4.1 Underlying technologies
Cnc25D rely on those open-source technologies:
• OpenCASCADE, the technology used by FreeCAD. Cnc25D doesn’t use directly OpenCASCADE.
• FreeCAD, the new open-source CAD tool.
• Python, the popular programming language.
1.4.2 Source
The source code is available at https://github.com/charlyoleg/Cnc25D. Feel free to clone and hack it!
1.4.3 Python package
The Cnc25D package is available on PyPI.
1.4. Links 7
Cnc25D Documentation, Release 0.1.11
1.4.4 Documentation
The Cnc25D release documentation is associated to the latest Cnc25D Python package release. The Cnc25D daily
built documentation provides you the latest documentation updates.
If you have Sphinx installed on your system and you have downloaded the Cnc25D Github repository, you can generate
locally the Html documentation with the following commands:
> cd Cnc25D/docs
> make html
With your browser open the local directory file:///.../Cnc25D/docs/_build/html .
1.5 License
(C) Copyright 2013 charlyoleg
The Cnc25D Python package is under GNU General Public License version 3 or any latter (GPL v3+).
1.6 Feedback and contact
If you find bugs, will suggest fix or want new features report it in the GitHub issue tracker or clone the Cnc25D GitHub
repository.
For any other feedback, send me a message to “charlyoleg at fabfolk dot com”.
1.7 Releases
Check the Cnc25D Release Notes.
8 Chapter 1. Cnc25D Presentation
CHAPTER 2
Cnc25D Release Notes
2.1 Release 0.1.11
Released on 2014-03-31
• low_torque_transmission
• gearlever
2.2 Release 0.1.10
Released on 2014-01-31
• refactoring/standardizing the designs with bare_design
2.3 Release 0.1.9
Released on 2013-12-13
• complete the Cnc25D API with generic functions for figures
• motor_lid
• bell
• bagel
• bell_bagel
• crest
• cross_cube
• gimbal
2.4 Release 0.1.8
Released on 2013-11-07
• add crenels to the gearwheel
9
Cnc25D Documentation, Release 0.1.11
• epicyclic-gearing
• axle_lid
2.5 Release 0.1.7
Released on 2013-10-07
• unify the test-environment of the macro-scripts
• use python-dictionary as function-argument for designs with many parameters
• gearring (aka annulus)
• gearbar (aka rack)
• split_gearwheel
2.6 Release 0.1.6
Released on 2013-09-25
• Use arc primitives for generating DXF and SVG files
• finalization of gear_profile.py and gearwheel.py
2.7 Release 0.1.5
Released on 2013-09-18
• GPL v3 is applied to this Python package.
2.8 Release 0.1.4
Released on 2013-09-11
• Python package created with setuptools (instead of distribute)
• add API function smooth_outline_c_curve() approximates a curve defined by points and tangents with arcs.
• integrate circle into the format-B
• add API functions working at the figure-level : figure_simple_display(), figure_to_freecad_25d_part(), ..
• remove API function cnc_cut_outline_fc()
• gear_profile.py generates and simulates gear-profiles
• gearwheel.py
10 Chapter 2. Cnc25D Release Notes
Cnc25D Documentation, Release 0.1.11
2.9 Release 0.1.3
Released on 2013-08-13
• New API function outline_arc_line() converts an outline defined by points into an outline of four possible
formats: Tkinter display, svgwrite, dxfwrite or FreeCAD Part.
• API function cnc_cut_outline() supports smoothing and enlarging line-line, line-arc and arc-arc corners.
• Additional API functions such as outline_rotate(), outline_reverse()
• All Cnc25D API function are gathered in the cnc25d_api module
• Box wood frame design example generates also BRep in addition to STL and DXF.
• Box wood frame design example support router_bit radius up to 4.9 mm with all others parameters at default.
2.10 Release 0.1.2
Released on 2013-06-18
• Box wood frame design example
2.11 Release 0.1.1
Released on 2013-06-05
• Experimenting distribute
2.12 Release 0.1.0
Released on 2013-06-04
• Initial release
2.9. Release 0.1.3 11
Cnc25D Documentation, Release 0.1.11
12 Chapter 2. Cnc25D Release Notes
CHAPTER 3
Cnc25D API Overview
3.1 Cnc25D Workflow
FreeCAD provides many GUI and API functions to sculpt and assemble 3D designs. Cnc25D proposes a script
methodology and an API on top of the FreeCAD API to design 2.5D parts.
13
Cnc25D Documentation, Release 0.1.11
3.1.1 The Cnc25D methodology
1. Create a list of 2D points you want that your outline go through. An outline is a list of lines and/or arcs. Other
curve type must be using multiple small lines.
2. Enlarge or Smooth the corners of the outline to do it makeable by a 3-axis CNC. The cnc25d_api.cnc_cut_outline()
function do it for you. It returns a new list of 2D points defining the new lines and arcs of the new outline.
3. Exploit the 2D outline. This new outline can already be export as SVG or DXF. It can also be displayed using
Tkinter. Finally, it can be converted intor FreeCAD Part outline to be extruded in 3D part.
4. Create your 3D assembly. After creating the 3D parts with the FreeCAD Part API, cnc25d_api.place_plank()
provides a more natural way to place 3D parts in an assembly than the standard rotate() and translate() methods.
5. Export your design. Export a cut of a 3D parts with cnc25d_api.export_2d(). Get a 3D scanning of your assembly
with cnc25d_api.export_xyz_to_dxf()
3.2 Cnc25D API functions and class
cnc25d_api.importing_freecad() => 0
cnc25d_api.outline_shift_x(outline-AB, x-offset, x-coefficient) => outline-AB
cnc25d_api.outline_shift_y(outline-AB, y-offset, y-coefficient) => outline-AB
cnc25d_api.outline_shift_xy(outline-AB, x-offset, x-coefficient, y-offset, y-coefficient) => outline-AB
cnc25d_api.outline_rotate(outline-AB, center-x, center-y, rotation_angle) => outline-AB
cnc25d_api.outline_close(outline-AB) => outline-AB
cnc25d_api.outline_reverse(outline-AB) => outline-AB
cnc25d_api.cnc_cut_outline(outline-A, error_mark_string) => outline-B
cnc25d_api.smooth_outline_c_curve(outline-C, precision, router_bit_radius, error_mark_string) => outline-B
cnc25d_api.smooth_outline_b_curve(outline-B, precision, router_bit_radius, error_mark_string) => outline-B
cnc25d_api.ideal_outline(outline-AC, error_mark_string) => outline-B
cnc25d_api.outline_arc_line(outline-B, backend) => Tkinter or svgwrite or dxfwrite or FreeCAD stuff
cnc25d_api.Two_Canvas(Tkinter.Tk()) # object constructor
cnc25d_api.figure_simple_display(graphic_figure, overlay_figure) => 0
cnc25d_api.write_figure_in_svg(figure, filename) => 0
cnc25d_api.write_figure_in_dxf(figure, filename) => 0
cnc25d_api.figure_to_freecad_25d_part(figure, extrusion_height) => freecad_part_object
14 Chapter 3. Cnc25D API Overview
Cnc25D Documentation, Release 0.1.11
cnc25d_api.place_plank(freecad_part_object, x-size, y-size, z-size, flip, orientation, x-position, y-position, z-position) => freecad_part_object
cnc25d_api.export_to_dxf(freecad_part_object, direction_vector, depth, filename) => 0
cnc25d_api.export_xyz_to_dxf(freecad_part_object, x-size, y-size, z-size, x-depth-list, y-depth-list, z-depth-list, filename) => 0
cnc25d_api.mkdir_p(directory) => 0
cnc25d_api.get_effective_args(default_args) => [args]
cnc25d_api.generate_output_file_add_argument(argparse_parser) => argparse_parser
cnc25d_api.generate_output_file(figure, filename, extrusion_height) => 0
3.2. Cnc25D API functions and class 15
Cnc25D Documentation, Release 0.1.11
16 Chapter 3. Cnc25D API Overview
CHAPTER 4
Cnc25D API Outline Creation
4.1 Cnc25D outline
Cnc25D helps you to work on outline before extruding it into 3D parts. Cnc25D outlines are defined in the XY-plan
and consist of a series of lines and/or arcs. A lineis defined by a start point and an end point. An arcis defined by a
start point, a passing-through point and an end point.
Manipulating Cnc25D outline consists of working on 2D points. This requires much less CPU resources as invoking
a complete 3D software. If you want to create other types of curve than lines or arcs, you must approximate those
curves with multiple small lines.
Cnc25D outline vocabulary:
• outline: a series of segments
• segment: a line or an arc
• start-point: the starting point of a line or an arc
• end-point: the ending point of a line or an arc
• middle-point: the passing-through point of an arc (it doesn’t have to be in the middle of the arc)
• first-point: the start point of the first segment of an outline
• corner: the junction between two consecutive segments.
• corner-point: the end-point of the previous segment or the start-point of the next segment
17
Cnc25D Documentation, Release 0.1.11
•rbrr : the router_bit radius request (how to transform a corner to do it millable by a router_bit of radius R?)
• closed outline: True if the end-point of the last segment is equal to the first-point
• outline orientation: Counter Clock Wise (CCW) or Clock Wise (CW) (this has a meaning only for closed outline)
• curved outline: outline representing a curve. The outline approximates the curve with some discrete points.
• tangent inclination: angle between the (Ox) direction and the oriented tangent of a point of an oriented curve.
• outline format A: pythonic description of an outline used as argument by the function
cnc25d_api.cnc_cut_outline()
• outline format B: pythonic description of an outline returned by cnc25d_api.cnc_cut_outline() and used as ar-
gument by cnc25d_api.outline_arc_line()
• outline format C: pythonic description of a curved-outline used as argument by the function
cnc25d_api.smooth_outline_c_curve()
• figure: list of format-B outlines
4.2 Cnc25D outline format A
In short, the Cnc25D outline format A is a list of list of 3 or 5 floats.
The purpose of the Cnc25D outline format A is to define your wished outline. In addition to the start, middle and
end points of the segments, you define for each corner the associated rbrr. That means that you can request different
router_bit radius for each corner. In general, you will set the same value for all corners of your outline. But you also
have the flexibility to set different rbrr for each corner.
The first element of the outline format A list is the first-point . It is defines by a list of 3 floats: X-coordinate, Y-
coordinate and the rbrr of the first-point .
The second element of the outline format A list is the first segment of the outline. If the first segment is a line, it is
defines by a list of 3 floats: end-point-X, end-point-Y and the rbrr of the end-point of the segment. If the first segment
is an arc, it is defines by a list of 5 floats: middle-point-X, middle-point-Y , end-point-X, end-point-Y and the rbrr of
the end-point of the segment.
All elements of the outline format A list define a segment except the first element that defines the first-point . An
outline composed of N segments is described by a list of N+1 elements. A segment is defined by 3 floats if it is a line
or 5 floats if it is an arc. The start-point of a segment is never explicitly defined as it is the end-point of the previous
segment. If the X and Y coordinates of the end-point of the last segment are equal to the X and Y coordinates of the
first-point of the outline, the outline is closed.
rbrr (a.k.a router_bit radius request ) defines how cnc25d_api.cnc_cut_outline() must modify a corner:
• if rbrr = 0, the corner is unchanged
• if rbrr > 0, the corner is smoothed to fit the router_bit radius rbrr
18 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
• if rbrr < 0, the corner is enlarged to fit the router_bit radius abs(rbrr)
Good practice : If the outline is closed, the rbrr of the last segment must be set to zero. If the outline is open (i.e. not
closed), the rbrr of the first-point and the rbrr of the last segment must be set to zero.
Theoutline format A can be defined with listortuple . The orientation of a closed outline can be CCW or CW.
outline format A example:
outline_A = [
[ 0, 0, 10], # first-point
[ 50, 0, 15], # horizontal line
[ 43, 43, 0, 50, 20], # arc
[ 0, 0, 0]] # vertical line and close the outline
4.3 Cnc25D outline format B
TheCnc25D outline format B is either a circle or ageneral outline .
In short, a format-B circle is a list of 3 floats (center-x, center-y, radius). The Cnc25D general outline format B is a
list of list of 2 or 4 floats.
The purpose of the Cnc25D general outline format B is to define an outline with points. In the general case, this is a
simplification of the outline format A , where the rbrr information is removed.
The first element of the general outline format B list is the first-point . It is defines by a list of 2 floats: X-coordinate,
Y-coordinate.
The second element of the general outline format B list is the first segment of the outline. If the first segment is a line,
it is defines by a list of 2 floats: end-point-X, end-point-Y . If the first segment is an arc, it is defines by a list of 4 floats:
middle-point-X, middle-point-Y , end-point-X, end-point-Y .
All elements of the general outline format B list define a segment except the first element that defines the first-point .
An outline composed of N segments is described by a list of N+1 elements. A segment is defined by 2 floats if it is
a line or 4 floats if it is an arc. The start-point of a segment is never explicitly defined as it is the end-point of the
previous segment. If the X and Y coordinates of the end-point of the last segment are equal to the X and Y coordinates
of the first-point of the outline, the outline is closed.
4.3. Cnc25D outline format B 19
Cnc25D Documentation, Release 0.1.11
Thegeneral outline format B can be defined with listortuple . The orientation of a closed outline can be CCW or CW.
general outline format B example:
outline_B = [
[ 0, 0], # first-point
[ 50, 0], # horizontal line
[ 43, 43, 0, 50], # arc
[ 0, 0]] # vertical line and close the outline
4.4 Cnc25D outline format C
In short, the Cnc25D outline format C is a list of list of 3 floats.
The purpose of the Cnc25D outline format C is to define a curved-outline with points and tangents. This is an extension
of the outline format B , where the tangent inclination is added at each point. This format must be preferred to described
a curved-outline.
Each element of the outline format C list is a curve sampling point. It is defines by a list of 3 floats: X-coordinate,
Y-coordinate and the tangent inclination angle . The first element of the outline format C list is the first-point . The
outline is oriented from the first-point to its last point. The tangent inclination is the angle (included in [-pi, pi])
between the (Ox) direction vector and the oriented curve tangent at the considered sampling point.
Theoutline format C can be defined with listortuple .
outline format C example (the X,Y coordinates and the tangent inclination angle are rounded for a better readability):
outline_C = [
[ 10, 0, math.pi/6], # first-point
[ 20, 5, math.pi/3],
[ 30, 15, math.pi/2],
[ 40, 20, math.pi/4],
[ 50, 22, math.pi/8]]
20 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
TheCnc25D outline format C is used as argument by the function cnc25d_api.smooth_outline_c_curve() .
If the curved-outline contains one or several inflexion points, it is recommended to chose those points as sampling
points. Thus the function cnc25d_api.smooth_outline_c_curve() is able to smooth the entire curved-outline. Otherwise
segments containing an inflexion point are leave as line by the function cnc25d_api.smooth_outline_c_curve() .
4.5 The function Cnc_cut_outline()
cnc25d_api. cnc_cut_outline( list, string )
Return a list.
4.5.1 cnc_cut_outline purpose
If you work with 3-axis CNC, your free XY-path gets actually some constraints due to the router_bit diameter. Real
inner angle can not be manufacture and must be replaced either by a smoothed angle or an enlarged angle.
4.5. The function Cnc_cut_outline() 21
Cnc25D Documentation, Release 0.1.11
Thecnc_cut_outline function aims at converting an outline defined by a list of points into an outline with lines and
arcs makable by a 3-axis CNC. For each point, you choose if you want to enlarge the angle, smooth it or leave it sharp.
Look at the CNC Cut Outline Details chapter to get more information on when you should enlarge and when you
should smooth a corner angle.
4.5.2 cnc_cut_outline usage
The cnc_cut_outline() function provides three possibilites as corner transformation: smooth, unchange, enlarge.
22 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
Ifrbrr (a.k.a. router_bit radius request) is positive, the angle is smoothed. If rbrr is negative, the angle is enlarged. If
rbrr is zero, the angle is unmodified.
Smoothing a corner is a closed problem: there is only one arc of radius R (= rbrr) that is tangent to the two adjacent
segments.
4.5. The function Cnc_cut_outline() 23
Cnc25D Documentation, Release 0.1.11
Enlarging a corner is an open problem: there are several arcs of radius R (= rbrr) that can clear the wished outline.
Cnc25D chose the arc of radius R (= rbrr) of which the center is on the line defined by the corner-point and the center
of the associated smoothed corner. If you want an other solution, you can modify slightly your wished outline (in
format A) to influence the final result as shown in the next paragraph alternative enlarged corner .
Notice that the interior of an closed outline is not influencing the process of smoothing or enlarging a corner. Only the
local geometry (namely the two adjacent segments) influence this process.
The cnc_cut_outline() function needs as argument an outline of format A and returns an outline of format B . The
24 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
format B outline can easily be converted into a FreeCAD Part Object, that can be after some conversions be extruded:
my_outline_A = [
[ 0.0 , 0.0, 0.0], # this corner will be leaved sharp
[ 20.0 , 0.0, 5.0], # this corner will be smoothed
[ 0.0 , 20.0, -5.0]] # this corner will be enlarged
my_outline_B = (cnc25d_api.cnc_cut_outline(my_outline_A, "demo_my_outline_A")
my_part_face = Part.Face(Part.Wire(cnc25d_api.outline_arc_line(my_outline_B, 'freecad').Edges))
my_part_solid = my_part_face.extrude(Base.Vector(0,0,20))
Look at the script cnc25d_api_example.py that you can generate with the executable cnc25d_example_generator.py
for a more complete example.
If the requested router_bit radius is too large, the corner transformation may not be applied because of geometrical
constraints. You get a warning orerror message containing string set as argument. A good practice is to set string to
the function name that calls cnc_cut_outline() . So you can find out which outline is not compatible with the requested
router_bit radius in case of error. Below an example of warning message due to a too large router_bit radius . Thanks
to the string , we know that the outline issue is located in the plank_z_side function:
WARN301: Warning, corner plank_z_side.1 can not be smoothed or enlarged because edges are too short!
4.5.3 Alternative enlarged corner
As the problematic of enlarging a corner doesn’t have a unique solution, you may want an other enlarging corner than
the default one proposed by cnc_cut_outline() . For example, you may want to enlarge a corner without milling one of
the adjacent segment. By changing the input outline, you can achieve it:
For comparison, the default result would be:
4.5. The function Cnc_cut_outline() 25
Cnc25D Documentation, Release 0.1.11
4.6 The function smooth_outline_c_curve()
cnc25d_api. smooth_outline_c_curve( list, float, float, string )
Return a list.
It reads a format C outline and returns a format B outline with the following characteristics:
• the outline is made out of arcs
• the outline goes through the sampling points
• the outline tangent at the sampling points has the requested direction (a.k.a. tangent inclination)
• the outline tangent is continuous
With an input format C outline of (N+1) points (i.e. N segement), the function smooth_outline_c_curve() returns a
format B outline of 2*N arcs. If a segment contains an inflexion point, the arcs are replace by a line. If input points
are aligned or almost aligned, arcs are also replaces by lines.
If the input curve contains inflexion points, choose these points as sampling points. This way, the function
smooth_outline_c_curve() can returns an approximated outline containing only arcs. In this case, the outline tangent
is continuous along the full path.
To approximate a mathematical or free-hand curve, it is better to use arcs than lines because with arcs you can keep the
property of continuous tangent. Most of the 3-axis CNC can handle arcs at the motor driving level. So this function
helps you to integrate your curve into a high quality workflow.
float ai_precision : defines the minimal angle to consider that points are not aligned and arcs must be created. Typical
value: pi/1000.
flaot ai_router_bit_request : defines the minimal radius of curvature of the returned outline. If a computed arc has
a radius smaller than ai_router_bit_request , a warning message is printed without changing the returned outline. Set
ai_router_bit_request to your router_bit radius . If you get warnings, create a more regular curve or choose a smaller
router_bit.
string ai_error_msg_id : this string is added in the error message and helps you to track bugs.
26 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
For more details on the implementation of smooth_outline_c_curve() , read the chapter Smooth Outline Curve Details
4.7 The function smooth_outline_b_curve()
cnc25d_api. smooth_outline_b_curve( list, float, float, string )
Return a list.
It reads a format B outline and returns a format B outline with the same characteristics as smooth_outline_c_curve() .
The function smooth_outline_b_curve() guests the curve tangent at each sampling point according to the previous and
following sampling points and then computes the approximated outline with arcs using smooth_outline_c_curve() . The
result is poorer than using smooth_outline_c_curve() because the curve tangents are approximated. Use this function
only when you can not get the tangent inclinations at the sampling points.
4.8 Other outline help functions
Cnc25D outline format A andBreduce the description of an outline to the 2D coordinates of points. That’s a drastic
reduction of the amount of Data and still keeping the description accurate. But for complex outlines, a large list of
point coordinates might become unreadable. It is preferable, to split a large list into comprehensive smaller sub-paths
and then concatenate them. Often patterns will be used several times for an outline with some slight modifications like
position (of course), scale, mirror or rotation. This is the purpose of the outline help functions .
The outline help functions accept as argument the Cnc25D outline format A and the Cnc25D outline format B and
return the outline with the same format:
cnc25d_api.outline_shift_x(outline_AB, x-offset, x-coefficient)
cnc25d_api.outline_shift_y(outline_AB, y-offset, y-coefficient)
cnc25d_api.outline_shift_xy(outline_AB, x-offset, x-coefficient, y-offset, y-coefficient)
cnc25d_api.outline_rotate(outline_AB, center-x, center-y, rotation_angle)
cnc25d_api.outline_close(outline_AB)
cnc25d_api.outline_reverse(outline_AB)
4.8.1 outline_shift
cnc25d_api. outline_shift_x( list, x-offset, x-factor )
4.7. The function smooth_outline_b_curve() 27
Cnc25D Documentation, Release 0.1.11
cnc25d_api. outline_shift_y( list, y-offset, y-factor )
cnc25d_api. outline_shift_xy( list, x-offset, x-factor, y-offset, y-factor )
Return a list that defines a sub-sequence of outline.
The definition an outline can be quiet long and tedious. It might be useful to split a long list of points into several
small sequences and concatenate them into one big list using the .append() and.extend() methods. Often it happens
that sub-sequence patterns appear several times in one outline either shifted or mirrored. The functions outline_shift_x ,
outline_shift_y and outline_shift_xy can be use to help the reuse of outline sub sequences. Let’s look at the following
example.
If we want to define this outline brutally, we must create a list of 28 points. But we can also define first the blue and
the green sub-sequences, which are each 3 points and create the complete outline out of them:
# We follow the points in the counter clock wise (CCW)
green_sequence = [
[ 10, 0, 0],
[ 20, 10, 0],
[ 20, 0, 0]]
blue_sequence = [
[ 0, 25, 0],
[ 10, 25, 0],
[ 0, 20, 0]]
width = 100
height = 80
my_outline = []
my_outline.append([0, 0, 0])
my_outline.extend(blue_sequence)
my_outline.extend(outline_shift_x(blue_sequence, width, -1))
my_outline.append([width, 0, 0])
my_outline.extend(outline_shift_x(green_sequence, width, -1))
my_outline.extend(outline_shift_xy(green_sequence, width, -1, height, -1))
my_outline.append([width, height, 0])
my_outline.extend(outline_shift_xy(blue_sequence, width, -1, height, -1))
my_outline.extend(outline_shift_y(blue_sequence, height, -1))
my_outline.append([0, height, 0])
28 Chapter 4. Cnc25D API Outline Creation
Cnc25D Documentation, Release 0.1.11
my_outline.extend(outline_shift_y(green_sequence, height, -1))
my_outline.extend(green_sequence)
This code is easier to maintain.
4.8.2 outline_rotate
cnc25d_api.outline_rotate(outline_AB, center-x, center-y, rotation_angle)
returnoutline_AB
It applies a rotation of center (x,y) and angle rotation_angle to each points of the input outline.
4.8.3 outline_close
cnc25d_api.outline_close(outline_AB)
returnoutline_AB
If the input outline is open, it closes it with a straight line (from the end-point of the last segment to the first-point).
4.8.4 outline_reverse
cnc25d_api.outline_reverse(outline_AB)
returnoutline_AB
It reverses the order of the segments. If the outline is closed, that reverses its orientation (from CCW to CW or
opposite). Notice that the .reverse() python method would not return a valid outline (format A or B) because of the
first-point and the middle-point of arcs.
4.9 ideal_outline()
cnc25d_api.ideal_outline(outline-AC, error_mark_string)
returnoutline-B
The function ideal_outline() lets you quickly convert a format-A or format-C outline into a format-B outline by drop-
ping the additional information contained in the format-A and format-C. The returned format-B outline is probably to
suitable for a 3-axis CNC. But you can display this ideal orwished outline in the Tkinter GUI to check the outline
construction.
4.9. ideal_outline() 29
Cnc25D Documentation, Release 0.1.11
30 Chapter 4. Cnc25D API Outline Creation
CHAPTER 5
CNC Cut Outline Details
5.1 Introduction to the automated cutting technology
Computer numerical control (a.k.a. CNC) lets cut material directly from computer design file (dxf, stl, g-code ...).
This ensures precision, reproducibility, shape-complexity and automation.
The 3-axis CNC can process:
• 2.5D : xy-path at z constant
• 3D: xyz-path in case of well adapted router_bit and path
Cutting technology:
• laser cutter (Only 2D: cutting and engraving)
• water jet (Only 2D with a 3-axis machine)
• mechanical router_bit (2.5D and 3D depending on shape and router_bit shape)
• electrical discharge machining
31
Cnc25D Documentation, Release 0.1.11
5.2 2D path constraints
Minimal curve radius constraint:
• laser and water-jet requests no specific constraint
• For mechanical router_bit, inner curve must have a curve radius bigger than the router_bit radius.
So inner corner can not be cut with router_bit. They must be replaced by inner curve. Tight inner curve must be
smoothed to respect the minimal curve radius constraint.
32 Chapter 5. CNC Cut Outline Details
Cnc25D Documentation, Release 0.1.11
5.2.1 Coplanar fitting
If you want a perfect fitting between two coplanar shapes, then outer corners and outer curves must be rounded to
get a minimum curve radius bigger than the router_bit radius. For a perfect fitting, two coplanar shapes must be
complementary.
5.2. 2D path constraints 33
Cnc25D Documentation, Release 0.1.11
5.2.2 Incoplanar fitting
If two parts, made out of 2D shape cut in a plan, are not coplanar, then rounding corner doesn’t help the fitting of the
two parts.
For fitting not coplanar shapes, we need to enlarge inner corners.
34 Chapter 5. CNC Cut Outline Details
Cnc25D Documentation, Release 0.1.11
5.3 Coplanar fitting details
For fitting two coplanar shapes, the inner and outer corners must be smoothed.
This section details the calculation related to smoothed line-line corner . To get the calculation related to
smoothed line-arc corner andsmoothed arc-arc corner , check the SVG files docs/smooth_corner_line_arc.svg and
docs/smooth_corner_arc_arc.svg .
5.3. Coplanar fitting details 35
Cnc25D Documentation, Release 0.1.11
(D1), (D2) : two straight lines
A : intersection of (D1) and (D2)
(C) : circle or radius (r) tangent to (D1) and (D2)
E : intersection of (C) and (D1)
F : intersection of (C) and (D2)
O : the center of (C)
(EAF)=a is the angle between (D1) and (D2)
(C) is tangent to (D1), so (D1) is perpendicular to (EO)
(C) is tangent to (D2), so (D2) is perpendicular to (FO)
FO=EO=r, so O belongs to the bisector of (EAF)
We have AF=AE and (FA0)=(EAO)=a/2
AEO is right triangle in E
tan(EAO) = OE/AE
AE = r/tan(a/2)
sin(EAO) = OE/AO
AO = r/sin(a/2)
Knowing Gx,Gy,Ax,Ay,Hx,Hy, we want to calculate: a
(xAG) = atan((Gy-Ay)/(Gx-Ax))
(xAH) = atan((Hy-Ay)/(Hx-Ax))
a=(EAF)=(GAH)=(xAH)-(aAG)
a=atan((Hy-Ay)/(Hx-Ax))-atan((Gy-Ay)/(Gx-Ax))
Other method with the law of cosines c²=a²+b²-2*a*b*cos(C)
In the triangle GHA:
h=AG=sqrt((Gx-Ax)²+(Gy-Ay)²)
g=AH=sqrt((Hx-Ax)²+(Hy-Ay)²)
a=GH=sqrt((Hx-Gx)²+(Hy-Gy)²)
a=(GAH)=acos((h²+g²-a²)/(2 *g*h))
36 Chapter 5. CNC Cut Outline Details
Cnc25D Documentation, Release 0.1.11
Knowing Gx,Gy,Ax,Ay,Hx,Hy,a we want to calculate: Ex,Ey,Fx,Fy
Ex=Ax+(Gx-Ax) *AE/AG
=Ax+(Gx-Ax) *r/(tan(a/2) *sqrt((Gx-Ax)²+(Gy-Ay)²))
I is the intersection of (C) and (AO)
(D3) is the straight line perpendicular to (AO) and including I
K is the intersection of (D3) and (D1)
L is the intersection of (D3) and (D1)
The triangles KAI and IAL are similar so AL=AK
(LAI)=(IAK)=a/2
AI=AO-IO=r/sin(a/2)-r=r *(1-sin(a/2))/sin(a/2)
AK=AI/cos(a/2)=r *(1-sin(a/2))/(sin(a/2) *cos(a/2))=r *(1-sin(a/2)) *2/sin(a)
AJ=AK+AL=(AI+IL)+(AI+IK)=2 *AI
AI=(AK+AL)/2
Kx=Ax+(Gx-Ax) *AK/AG
5.3. Coplanar fitting details 37
Cnc25D Documentation, Release 0.1.11
Knowing Gx,Gy,Ax,Ay,Hx,Hy,a we want to calculate: Ix, Iy
With E,I and F, we define the arc than can be build with a router_bit of radius r.
5.4 Incoplanar fitting details
For fitting two not-coplanar shapes, the inner corners must be enlarged.
This section details the calculation related to enlarged line-line corner . To get the calculation related to enlarged
line-arc corner andenlarged arc-arc corner , check the SVG filedocs/enlarge_corner_arc_arc.svg .
5.4.1 Angle types
Case of an inner obtuse angle
Border case of an inner right angle
38 Chapter 5. CNC Cut Outline Details
Cnc25D Documentation, Release 0.1.11
Case of an inner acute angle
5.4.2 Calculation
Let's consider three points A, G and H.
(D1) is the bisector of (GAH).
O is a point of (D1) such as AO=r
(C1) is the circle of center O and radius r
E is the intersection of (C1) and (AG)
F is the intersection of (C1) and (AH)
(D2) is the straight line perpendicular to (D1) and including O
K and L are the intersection of (D2) with (C1)
5.4. Incoplanar fitting details 39
Cnc25D Documentation, Release 0.1.11
Let's calculate AE:
OA=OE=r
We define I, the orthogonal projection of O on (AE)
AI=EI because AEO is isosceles in O
AI=AO/cos(a/2)=r *cos(a/2)
AE=2*r*cos(a/2)
(D3) is the straight line perpendicular to (D1) and such that the length MN is equal to 2 *r with M the intersection of (D3) and (AG) and N the intersection of (D3) and (AH).
P is the intersection of (D3) and (D1).
AM=r/sin(a/2)
R is the middle of [AM]
S is the middle of [AN]
V is the intersection of (D2) and (AH)
W is the intersection of (D) and (AG)
AK=AR-AS+(AV+AW)/2
AR=AS=r/(2 *sin(a/2))
AV=AW=r/cos(a/2)
40 Chapter 5. CNC Cut Outline Details
CHAPTER 6
Smooth Outline Curve Details
6.1 1. Curve approximation
Most of the 3-axis CNC can handle arcs at the motor driving level. This means that arcs, like lines, can be done
perfectly at the mechanical precision. All other curve types must be approximated either with small lines or in small
arcs in an earlier stage of the design workflow.
Approximating with lines is simple but you lose the continuity of the tangent along the path.
Approximating with arcs let you keep the continuity of the tangent along the path. This is probably what you want to
approximate your mathematical curve or your free-hand curve.
6.2 2. Double-arc solution
The function smooth_outline_c_curve() use the double-arc solution to approximate a segment of curve.
Given two points, A and E, and their tangent directions, you can construct two arcs that are joined in C with a common
tangent direction (parallel to the line (AE)) and with the first arc that starts in A with the requested tangent direction
and the second arc that ends in E with the requested tangent direction.
41
Cnc25D Documentation, Release 0.1.11
42 Chapter 6. Smooth Outline Curve Details
Cnc25D Documentation, Release 0.1.11
6.2. 2. Double-arc solution 43
Cnc25D Documentation, Release 0.1.11
The file docs/smooth_polyline.svg contains other solution attempts.
44 Chapter 6. Smooth Outline Curve Details
CHAPTER 7
Cnc25D API Outline Utilization
7.1 Transformations at the figure-level
The description of a 2.5D part can require several outlines. Typically one outline is the outer shape of the part, the
other outlines are holes in this part. In the Cnc25D API, a list of outlines is called a figure . After creating such a list,
you can directly display this figure , write it in a file or extrude it in 3D with FreeCAD.
7.2 Display a figure in a GUI
cnc25d_api.figure_simple_display(graphic_figure, overlay_figure)
return0
graphic_figure is a list of format-B outlines to be displayed in red.overlay_figure is optional and could be used to
display an other figure in orange when the overlay is active. A common practice it to set graphic_figure with the
outlines returned by cnc_cut_outline() and to set overlay_figure with outlines returned by ideal_outline() . So you can
see your created format-A outlines and the final format-B outlines. Notice that you can also directly use format-A or
format-C without converting them in format-B with ideal_outline() , but you will get a warning message.
If you want more control on the figure display like new colors ,width oranimations , then you should use out-
line_arc_line() andTwo_Canvas directly.
7.3 Write a figure in a SVF file
cnc25d_api.write_figure_in_svg(figure, filename)
return0
7.4 Write a figure in a DXF file
cnc25d_api.write_figure_in_dxf(figure, filename)
return0
45
Cnc25D Documentation, Release 0.1.11
7.5 Extrude a figure using FreeCAD
cnc25d_api.figure_to_freecad_25d_part(figure, extrusion_height)
return FreeCAD Part Object
To create a 3D part from a figure , the function figure_to_freecad_25d_part() makes the assumption that the first outline
is the outer line and the remaining outlines are holes.
7.6 Detailed transformations at the outline-level
After getting a Cnc25D format B outline from the cnc_cut_outline() function, you probably want to use this outline in
CAD tools. The function cnc25d_api.outline_arc_line() lets you transform the Cnc25D format-B outline into one of
this four formats: freecad ,svgwrite ,dxfwrite ,tkinter .
cnc25d_api.outline_arc_line(outline-B, backend) => Tkinter or svgwrite or dxfwrite or FreeCAD stuff
with backend=['freecad', 'svgwrite', 'dxfwrite', 'tkinter']
7.6.1 freecad
outline_arc_line(outline_B, ‘freecad’) returns FreeCAD Part.Shape object that can be used easily in the classic
FreeCAD workflow:
my_part_shape = cnc25d_api.outline_arc_line(my_outline_B, 'freecad')
my_part_face = Part.Face(Part.Wire(my_part_shape.Edges))
my_part_solid = my_part_face.extrude(Base.Vector(0,0,20))
Notice that FreeCAD conserve the arcgeometrical entity during its complete workflow. So after extruding the outline,
slicing the part and then projecting it again in a DXF file, you still get the arcs you have designed in your original
outline.
7.6.2 svgwrite
ACnc25D format B outline is a 2D vectorial shape that can be transposed in a SVG file. SVG file is one of the usual
input format for the 3-axis CNC tool chain. This snippet let you dump the Cnc25D format B outline in aSVG file:
import svgwrite
my_outline_B = [ .. ]
object_svg = svgwrite.Drawing(filename = "my_ouline.svg")
svg_outline = cnc25d_api.outline_arc_line(my_outline_B, 'svgwrite')
for one_line_or_arc in svg_outline:
object_svg.add(one_line_or_arc)
object_svg.save()
Cnc25D relies on the Python package svgwrite from mozman . Use Inkscape to review the generated SVG file.
Warning: The SVG format supports the arcgraphical object but the Python package svgwrite has not implemented
yet the arcconstructor. So Cnc25D transform each arcof the outline into a series of small segments. This might be
an issue for certain CNC tool chain or for some designs.
7.6.3 dxfwrite
ACnc25D format B outline is a 2D vectorial shape that can be transposed in a DXF file:
46 Chapter 7. Cnc25D API Outline Utilization
Cnc25D Documentation, Release 0.1.11
import dxfwrite
my_outline_B = [ .. ]
object_dxf = DXFEngine.drawing("my_outline.dxf")
#object_dxf.add_layer("my_dxf_layer")
dxf_outline = cnc25d_api.outline_arc_line(my_outline_B, 'dxfwrite')
for one_line_or_arc in dxf_outline:
object_dxf.add(one_line_or_arc)
object_dxf.save()
Cnc25D relies on the Python package dxfwrite from mozman . Use LibreCAD to review the generated DXF file.
Warning: Like previously, the DXF format supports the arcgraphical object but the Python package dxfwrite has not
implemented yet the arcconstructor. So Cnc25D transform each arcof the outline into a series of small segments.
This might be an issue for certain CNC tool chain or for some designs.
7.6.4 tkinter
During the early phase of the design, you just need to view the outline (that still might be under-construction)
without using the powerful FreeCAD or dumping files. This is the purpose of the Tkinter GUI . Check the
design example cnc25d_api_example.py the binary cnc25d_example_generator.py or check the file
cnc25d/tests/cnc25d_api_macro.py to see how to implement this small graphic user interface .
cnc25d_api.Two_Canvas(Tkinter.Tk()) # object constructor
7.6. Detailed transformations at the outline-level 47
Cnc25D Documentation, Release 0.1.11
48 Chapter 7. Cnc25D API Outline Utilization
CHAPTER 8
Cnc25D API Working with FreeCAD
8.1 import FreeCAD
cnc25d_api. importing_freecad()
Modify the global variable sys.path .
FreeCAD comes with Python modules. But these FreeCAD modules are not installed in one of the standard directories.
You will find the Python FreeCAD modules in a directory such as /usr/lib/freecad/lib . To use FreeCAD from a Python
script, you need either to set the PYTHONPATH system environment variable or to extend the sys.path Python variable.
Because you need to import FreeCAD at each beginning of scripts, this task as been implemented in the module
cnc25d_api.py that is installed in a standard location. So, after installing Cnc25D, to use the FreeCAD modules, you
only need to add those lines at the beginning of your Python script:
from cnc25d import cnc25d_api
cnc25d_api.importing_freecad()
The function importing_freecad() looks for the FreeCAD modules using a location list. If the function import-
ing_freecad() doesn’t manage to find FreeCAD on your system, you may need to edit the module importing_freecad.py
and add the path to the FreeCAD modules to the FREECADPATH list.
8.2 place_plank()
cnc25d_api. place_plank( FreeCAD.Part.Object, x-size, y-size, z-size, flip, orientation, x-position, y-position,
z-posistion )
Return a FreeCAD.Part.Object
FreeCAD provides the usual rotate andtranslate methods to place an object in a construction-assembly. Even if those
methods are mathematically straight forward, they might require many tries and errors to find out the correct rotation
to apply to an object to place it correctly in an assembly. The place_plank() function provides an alternative to the
rotate method when you want to place a object in a cuboid assembly.
To help positioning object we have the following conventions:
• The largest size of an object defines the main axis of the object.
• The second largest size of an object defines the second axis of the object.
• During the object construction, we choose the X axis as main axis and the Y axis as second axis .
49
Cnc25D Documentation, Release 0.1.11
A cuboid assembly is a construction where most of the objects have their main axis parallel to the X, Y or Z-axis. To
place an object, construed with the above conventions, in a cuboid assembly, you can define the rotation of the object
with two natural parameters:
• the orientation of the main and second axis . There are just six possibilities: ‘xy’, ‘xz’, ‘yx’, ‘yz’, ‘zx’ and ‘zy’.
For example, ‘yx’ means that the main axis of the object is parallel to the Y-axis of the reference frame and the
second axis of the object is parallel to the X-axis.
• the flip of the object. After defining the orientation of the main axis andsecond axis , there are still four possi-
bilities called flip: ‘identity’, ‘x-flip’, ‘y-flip’ and ‘z-flip’.
Theplace_plank() function uses this approach to place a object in an cuboid assembly. To realize flip and orientation,
theplace_plank() function needs to know the sizes along X, Y and Z of the object. Those sizes are virtual and you can
play with them for your convenience.
A physical object can be defined in several ways respecting our main and second axis conventions. The choice of the
definition influences the behavior of the flip. Knowing that, choose the most convenient definitions for your design.
Look at the Plank Positioning Details chapter to get more explaination on rotation, orientation and flip transformations.
8.3 Drawing export
FreeCAD provides very efficient methods for 3D export such as .exportBrep() ,.exportStep() or.exportStl() . It also
provides full customizable 2D export methods such as .slice() andprojectToDXF() .Cnc25D provides simple functions
that covers the most standard usage of the 2D export.
8.3.1 Cut export as DXF
export_2d. export_to_dxf( FreeCAD.Part.Object, FreeCAD.Base.Vector, depth, path )
50 Chapter 8. Cnc25D API Working with FreeCAD
Cnc25D Documentation, Release 0.1.11
Write the DXF file path.
Theexport_to_dxf() function performs two successive operations:
• It cuts a slice of the FreeCAD.Part.Object according to the direction FreeCAD.Base.Vector and the depth .
• It writes the DXF file path containing the projection of the slice.
If you are designing a 2.5D part, this function is useful to get the DXF file that will be used by the CNC workflow.
Usage example:
export_2d.export_to_dxf(my_part_solid, Base.Vector(0,0,1), 1.0, "my_part.dxf")
8.3.2 Cut export as SVG
export_2d. export_to_svg( FreeCAD.Part.Object, FreeCAD.Base.Vector, depth, path )
Write the SVG file path.
Theexport_to_svg() function performs the same operations as export_to_dxf() except it write a SVG file.
Usage example:
export_2d.export_to_svg(my_part_solid, Base.Vector(0,0,1), 1.0, "my_part.svg")
Warning: The function export_to_svg() only works when it is used in a script run from the FreeCAD GUI. This is
because of a current limitation of the FreeCAD library function Drawing.projectToSVG() .
8.3.3 XYZ scanning
export_2d. export_xyz_to_dxf( FreeCAD.Part.Object, x-size, y-size, z-size, x-list, y-list, z-list, path )
Write the DXF file path.
Theexport_xyz_to_dxf() function cuts in many slices the FreeCAD.Part.Object according to the three directions of the
reference frame axis X, Y and Z. The depth of the slices are provided by the three argument lists x-list ,y-list andz-list .
All the slices are placed in the plan XY and are written in the DXF file path.
The result looks like a medical scan. This is a more comfortable and readable document than the CAD tradition 3
views projections. This helps to show up weaknesses of designs if you choose good slices.
8.3. Drawing export 51
Cnc25D Documentation, Release 0.1.11
Usage example:
xy_slice_list = [ 0.1+20 *iforiinrange(12) ]
xz_slice_list = [ 0.1+20 *iforiinrange(9) ]
yz_slice_list = [ 0.1+20 *iforiinrange(9) ]
export_2d.export_xyz_to_dxf(my_assembly, 180.0, 180.0, 240.0, xy_slice_list, xz_slice_list, yz_slice_list, "my_assembly.dxf")
52 Chapter 8. Cnc25D API Working with FreeCAD
CHAPTER 9
Plank Positioning Details
9.1 Plank definition
We call plank a 3D shape with a rectangular cuboid as construction base. The rectangular cuboid is defined by the
three values: length, width and height with the relations: length > width > height. With addition ad-hoc conventions,
any shape can be considered as a plank.
9.2 Plank reference frame
We choose the reference frame such as:
53
Cnc25D Documentation, Release 0.1.11
• x is the length direction
• y is the width direction
• z is the height direction
• the origin (O) is one of the corner of the base cuboid
• the main part of the plank has positive coordinates (x,y,z) in this reference frame
• (O,x,y,z) is orthonormal direct.
9.3 Plank flip possibilities
According to the plank reference frame definition, there are four possibilities to place the plank within this reference
frame.
54 Chapter 9. Plank Positioning Details
Cnc25D Documentation, Release 0.1.11
Notice that z-flip is equivalent to the combination of x-flip and y-flip.
9.4 Plank orientation possibilities
We focus only on cuboid construction. Namely each plank of the construction is parallel to one of the 3 axis X, Y and
Z of a given orthogonal reference frame.
Considering a simple plank (just a rectangular cuboid wihtout cut), the position of the plank is not influenced by flip
along x, y and z. In a given reference frame, this plank has six possible orientations in a cuboid construction. An
orientation is marked by the length direction axis followed by the width direction axis. With this nomenclature, the
six orientations are: ‘xy’, ‘xz’, ‘yx’, ‘yz’, ‘zx’ and ‘zy’.
9.4. Plank orientation possibilities 55
Cnc25D Documentation, Release 0.1.11
56 Chapter 9. Plank Positioning Details
Cnc25D Documentation, Release 0.1.11
9.5 Plank position in a cuboid construction
The position of a plank (or assimilated) in a cuboid construction can be defined by three operations:
• flip (identity, x-flip, y-flip, z-flip)
• orientation (‘xy’, ‘xz’, ‘yx’, ‘yz’, ‘zx’, ‘zy’)
• translation (x,y,z)
The function place_plank() realizes those operations. To realize those three operation, the function needs also as
argument the length, the width and the height of the plank.
9.5. Plank position in a cuboid construction 57
Cnc25D Documentation, Release 0.1.11
58 Chapter 9. Plank Positioning Details
CHAPTER 10
Cnc25D Internals
10.1 File layout
Cnc25D/
.gitignore
CHANGES.rst # Release change notes. Required by PyPI
LICENSE.txt # Applicable license
README.rst # README used by GitHUb and PyPI
setup.py # Python package distribution setup file
bin/ # contains binaries to be installed on the host system during the Cnc25D package installation
cnc25d_example_generator_src.py # source code of the cnc25d_example_generator.py script
cnc25d_example_generator.py # scr/micropreprocessor.py
cnc25d/ # the main package
__init__.py
importing_freecad.py # lets import the FreeCAD libraries
cnc_outline.py # cnc25d API to design parts
export_2d.py # cnc25d API to export DXF or SVG
box_wood_frame.py # box_wood_frame design example
tests/ # contains the test files of the cnc25d package
__init__.py
importing_cnc25d.py # modify sys.path to import the cnc25d library
cnc25d_api_macro.py # usage example of the cnc25d API. Reused by cnc25d_example_generator.py. Can not be executed directly.
box_wood_frame_macro.py # usage example of box_wood_frame. Reused by cnc25d_example_generator.py. Can not be executed directly.
docs/ # cnc25d package documentation sources
box_wood_frame.svg # SVG draft
box_wood_frame.txt # text autmatically extracted from the SVG draft
cnc25d_api.rst # source of the Sphinx generated documentation
index.rst # top file of the Sphinx documentation sources
conf.py # Sphinx configuration
Makefile # make clean html to rebuild the documentation
images/ # contains the images used by the Sphinx documentation
3_axis_cnc.png
scr/ # additional scripts for developers
micropreprocessor.py # lets generate cnc25d_example_generator.py
note_on_cnc25d_dev.txt # notes for developers
59
Cnc25D Documentation, Release 0.1.11
10.2 Design example generation
The binary script cnc25d_example_generator.py just writes example scripts. These example scripts are actually the
files cnc25d/tests/cnc25d_api_macro.py andcnc25d/tests/box_wood_frame_macro.py . The test-macro script must
have those lines at the beginning of the script, so it can be excuted in the source repository as well as in the installed
environment:
try:# when working with an installed Cnc25D package
from cnc25d import cnc25d_api
60 Chapter 10. Cnc25D Internals
Cnc25D Documentation, Release 0.1.11
except:# when working on the source files
import importing_cnc25d # give access to the cnc25d package
from cnc25d import cnc25d_api
cnc25d_api.importing_freecad()
Because of the Python package workflow, the example scripts can not be copied after the installation and must be
embedded in the binary script cnc25d_example_generator.py before the creation of the Python package distribution.
This is the purpose of the script scr/micropreprocessor.py . The file bin/cnc25d_example_generator_src.py contains
the skeleton of the script bin/cnc25d_example_generator.py . The following command include the example scripts to
generate the final script bin/cnc25d_example_generator.py :
> scr/micropreprocessor.py bin/cnc25d_example_generator_src.py
The purpose of this workflow is to help the maintenance of the generated example scripts and avoid bugs in their
content.
To create a new design example, follow those steps:
• Create the new design example file in the directory Cnc25D/cnc25d/tests/ with a file name such as
my_new_design_macro.py
• Check it by executing it
• Add the few lines in the file Cnc25D/bin/cnc25d_example_generator_src.py that includes the new script
Cnc25D/cnc25d/tests/my_new_design_macro.py
• Regenerate Cnc25D/bin/cnc25d_example_generator.py with the command:
> scr/micropreprocessor.py bin/cnc25d_example_generator_src.py
10.2. Design example generation 61
Cnc25D Documentation, Release 0.1.11
62 Chapter 10. Cnc25D Internals
Cnc25D Documentation, Release 0.1.11
10.3 Python package distribution release
10.4 Documentation process
SVG files are edited with Inkscape and are use as draft documents for pictures and texts. If you want to modify one
of the PNG of the documentation, you can find the vectorial source in one of the SVG files. After modifying the SVG,
save it and export the picture as PNG in the directory docs/images/ .
A good practice is to use a SVG document with a width of 600 pixels. It helps creating not too large pictures for a nice
fitting in html andpdfdocuments. Extend the height of the SVG document as much as you need it.
Texts can be extracted from the SVG files with the command:
> scr/svg2txt.py docs/ *.svg
The generated txtfiles are used for checking spelling and are raw material for the reStructuredText files.
The sources of the Sphinx documentation are only the reStructuredText files (*.rst) and the PNG files (*.png).
10.3. Python package distribution release 63
Cnc25D Documentation, Release 0.1.11
64 Chapter 10. Cnc25D Internals
CHAPTER 11
Creating a Cnc25D Design
You can use one of the existing Cnc25D Designs or create your own Cnc25D design using the Cnc25D API. To
create your own Cnc25D design , you can use your own ad-hoc way like in the Box Wood Frame Design variant
box_wood_frame_ng.py or use the recommended way using the class bare_design as explained in this page.
11.1 Design Script Example
ABC is the name of our Cnc25D design example.
import cnc25d_api
cnc25d_api.importing_freecad()
import Part # to show-up 3D in FreeCAD
import sys # to exit on error
import argparse # to define the ABC_design constraint
import math # usually useful to calcule point coordinates
defABC_constraint_constructor(parser):
""" define the ABC constraint constructor using the argparse description
"""
parser.add_argument('--length_A', '-a', action='store', type=float, default=10.0,
help="set the length_A of ABC. Default: 10.0")
parser.add_argument('--length_B', '-b', action='store', type=float, default=0.0,
help="set the length_B of ABC. If equal 0.0, set to length_A. Default: 0.0")
parser.add_argument('--smooth_radius', '--sr', action='store', type=float, default=0.0,
help="set the smooth-radius of the corners of ABC. Default: 0.0")
return(parser) # return an argparse object
defABC_constraint_check(c):
""" check the ABC constraint c and set the dynamic default values
"""
# dynamic default values
if(c['length_B']==0):
c['length_B'] = c['length_A']
# check the constraint
if(c['length_B']<c['length_A'] *0.1):
print("ERR129: Error, length_B {:0.3f} is too small compare to length_A {:0.3f}".format(c['length_B'], c['length_A']))
sys.exit(2)
return(c)# return a dictionary
defABC_figures(c):
""" construct the ABC 2D-figure-outlines at the A-format from the constraint c
It returns a dictionary of figures with outlines in the A-format
65
Cnc25D Documentation, Release 0.1.11
"""
r_figures = {}
r_height = {}
#
ABC_base_figure = []
ABC_external_outline_A = [] # the square
ABC_external_outline_A.append((0.0,0.0, c['smooth_radius']))
ABC_external_outline_A.append((0.0+c['length_A'], 0.0, c['smooth_radius']))
ABC_external_outline_A.append((0.0+c['length_A'], 0.0+c['length_B'], c['smooth_radius']))
ABC_external_outline_A.append((0.0, 0.0+c['length_B'], c['smooth_radius']))
cnc25d_api.outline_close(ABC_external_outline_A)
ABC_base_figure.append(ABC_external_outline_A)
#
r_figures['ABC_base'] = ABC_base_figure
r_height['ABC_base'] = c['length_A']
return((r_figures, r_height)) # return a tuple of two dictionaries
defABC_3d(c):
""" construct the ABC-assembly-configuration for 3D-freecad-object from the constraint c
It returns a dictionary of assembly-configurations
"""
r_assembly = {}
r_slice = {}
#
simple_abc_assembly = []
simple_abc_assembly.append(('ABC_base', 0.0, 0.0, c['length_A'], c['length_B'], c['length_A'], 'i', 'xy', 0, 0, 0))
#
size_xyz = (c['length_A'], c['length_B'], c['length_A'])
zero_xyz = (0.0, 0.0, 0.0)
slice_x = [ (i+1)/12.0 *size_xyz[0] foriinrange(10) ]
slice_y = [ (i+1)/12.0 *size_xyz[1] foriinrange(10) ]
slice_z = [ (i+0.1)/12.0 *size_xyz[2] foriinrange(10) ]
slice_xyz = (size_xyz[0], size_xyz[1], size_xyz[2], zero_xyz[0], zero_xyz[1], zero_xyz[2], slice_z, slice_y, slice_x)
#
r_assembly['abc_assembly_conf1'] = simple_abc_assembly
r_slice['abc_assembly_conf1'] = slice_xyz
return((r_assembly, r_slice)) # return a tuple of two dictionaries
defABC_info(c):
""" create the text info related to the ABC from the constraint c
"""
r_txt = """
length_A: \t{:0.3f}
length_B: \t{:0.3f}
smooth_radius: \t{:0.3f}
""".format(c['length_A'], c['length_B'], c['smooth_radius'])
return(r_txt) # return a string-text
defABC_self_test():
""" set the self_tests for the ABC-design
"""
r_tests = [
('default abc', ''),
('unregular abc', '--length_A 30.0 --length_B 20.0 --smooth_radius 8.0'),
('heigh abc', '--length_A 5.0 --length_B 5.0 --smooth_radius 2.0 --output_file_basename test_output/height_abc.dxf')]
return(r_tests) # return a list of 2-tuples
class ABC (bare_design):
66 Chapter 11. Creating a Cnc25D Design
Cnc25D Documentation, Release 0.1.11
""" ABC design
"""
def__init__(self, constraint={}):
""" configuration of the ABC design
"""
self.design_setup(
s_design_name = "ABC_design",
f_constraint_constructor = ABC_constraint_constructor,
f_constraint_check = ABC_constraint_check,
f_2d_constructor = ABC_figures,
d_2d_simulation = {},
f_3d_constructor = ABC_3d,
f_3d_freecad_constructor = None,
f_info = cube_info,
l_display_figure_list = [],
s_default_simulation = "",
l_2d_figure_file_list = [],
l_3d_figure_file_list = [],
l_3d_conf_file_list = [],
l_3d_freecad_file_list = None,
f_cli_return_type = None,
l_self_test_list = ABC_self_test())
self.apply_constraint(constraint)
if__name__ == "__main__":
my_abc = ABC()
my_abc.cli("--length_A 50.0 --length_B 30.0 --output_file_basename test_output/abc.dxf")
if(cnc25d_api.interpretor_is_freecad()):
Part.show(my_abc.get_fc_obj_3dconf('abc_assembly_conf1'))
11.2 Design Functions
A design is built via several mandatory and optional functions. After defining theses functions, they are bound to a
design during the design setup phase. The name of the function is irrelevant but their argument list and their returned
values are specified in this section. The argument list can be extended with optional arguments if you want to reuse
this function in an other context.
11.2.1 ABC_constraint_constructor()
# parser = argparse.ArgumentParser()
defABC_constraint_constructor(parser):
parser.add_argument('--my_constraint', '--mc', action='store', type=float, default=10.0,
help="my_constraint to parametrize the design. Default: 10.0")
return(parser)
TheABC_constraint_constructor() function defines the constraint list of the design. Each constraint is declared with
the method argparse.ArgumentParser().add_argument() . For one constraint, you can specigy the type ( float,integer ,
string ..), the default value and some explanation. Out of this parser argument list , a dictionary of the design constraint
is created using the longest name of each ârser argument .
11.2. Design Functions 67
Cnc25D Documentation, Release 0.1.11
11.2.2 ABC_constraint_check()
# c = { 'constraint_A' : 3.0, 'constraint_B' : 3.0 }
defABC_constraint_check(c):
c['constraint_C'] = c['constraint_A'] + c['constraint_B'] # create a new entry in the constraint dictionary
if(c['constraint_A']<2): # a dummy design rule check
print("Error: constraint_A {:0.3f} must be bigger than 2".format(c['constraint_A']))
sys.exit(2)
return(c)
TheABC_constraint_check() checks the coherence of the values set to the design constraint, completes the constraint
dictionary with new values or even modifies the constraint values. Most of the design rule check must occur inside
this function. To avoid headache to the users of you design, make sure the constraint default values pass the design
rule check.
11.2.3 ABC_figures()
68 Chapter 11. Creating a Cnc25D Design
Cnc25D Documentation, Release 0.1.11
defABC_figures(c)
r_figures = {}
r_height = {}
#
A_fig = [] # start the figure A_fig. A figure is list of outlines. The first outline is the external-outline. The other outlines are the hole-outlines.
quadrilateral = [] # start the outline quadrilateral. An outline can be a circle or a chain of lines and arcs.
quadrilateral.append((10, 20, 5)) # set the first point of the quadrilateral outline. A positive router_bit_radius of 5 is requested.
quadrilateral.append((80, 10, 0)) # set a line to the second point. The router_bit_radius request is set to 0. The corner will remain sharp.
quadrilateral.append((70, 50, 5)) # set a line to the third point. A positive router_bit_radius of 5 is requested. The corner will be smoothed with a radius of 5.
quadrilateral.append((10, 60, 5)) # set a line to the fourth point.
quadrilateral.append((10, 20, 0)) # set a line to the first point. The router_bit_radius request must be 0 because this is the last segment.
A_fig.append(quadrilateral) # the outline quadrilateral is added to the figure A_fig. quadrilateral is the external-outline because it is the first outline of A_fig.
hole_circle = (30, 40, 10) # define the outline hole_circle. A circle is an outline exception defined only by the tuple (center-x, center-y, radius).
A_fig.append(hole_circle) # the outline hole_circle is added to the figure A_fig. hole_circle is a hole because this is not the first outline of A_fig.
other_hole = [] # start the outline other_hole, consisting of a line and an arc.
other_hole.append((50, 10, -5)) # set the first point of the outline other_hole. A negative router_bit_radius of -5 is requested, so the corner will be enlarged.
other_hole.append((70, 10, 5)) # set a line to the second point. A positive router_bit_radius of 5 is requested.
other_hole.append((60, 20, 50, 10, 0)) # set an arc passing through an intermediate point and going back to the first point. The router_bit_radius request must be 0 because this is the last segment.
A_fig.append(other_hole) # the outline other_hole is added to the figure A_fig. other_hole is a hole because this is not the first outline of A_fig.
#
r_figures['A_figure'] = A_fig
r_height['A_figure'] = 10.0
return((r_figures, r_height))
TheABC_figures() defines the 2D-figures of the design. As we are focusing on 2.5D designs, it is probably the heart
of your design. The function must use as argument the constraint dictionary , that has already by processed by the
previous function ABC_constraint_check() . The function must return a tuple of to dictionaries containing the same
keys.
The first dictionary contains the 2D-figures, that are from a Python point of view a list of list of list.
The second dictionary contains the extrusion height of each figure. These heights are used by the function
write_figure_brep() . For some figures, like assembly figures, the height might not make any sense. In those cases, set
the height to the conventional value 1.0.
To generate the figures and outlines, you can use some function of the Cnc25D API:
• cnc25d_api.outline_shift_x(outline, x_offset, x_coefficient)
• cnc25d_api.outline_shift_y(outline, y_offset, y_coefficient)
11.2. Design Functions 69
Cnc25D Documentation, Release 0.1.11
• cnc25d_api.outline_shift_xy(outline, x_offset, x_coefficient, y_offset, y_coefficient)
• cnc25d_api.outline_rotate(outline, rotation_center_x, rotation_center_y, rotation_angle)
• cnc25d_api.outline_close(outline)
• cnc25d_api.outline_reverse(outline)
• cnc25d_api.rotate_and_translate_figure(figure, rotation_center_x, rotation_center_y, rotation_angle, trans-
late_x, translate_y)
• cnc25d_api.flip_rotate_and_translate_figure(figure, zero_x, zero_y, size_x, size_y, x_flip, y_flip, rota-
tion_angle, translate_x, translate_y)
For more details, read the chapter Cnc25D API Outline Creation.
11.2.4 ABC_3d()
defABC_3d(c)
r_assembly = {}
r_slice = {}
#
r_assembly['A_3dconf'] = [('A_figure', 0.0, 0.0, 70, 50, 30, 'i', 'xy', 0, 0, 0)]
r_slice['A_3dconf'] = (70, 50, 30, 10, 10, 0, [5, 15, 25], [20, 30, 40], [20, 30, 40])
#
return((r_assembly, r_slice))
The function ABC_3d() defines the 3D assembly generated from the extruded 2D-figures. The function must use as
argument the constraint dictionary , that has already by processed by the previous function ABC_constraint_check() .
The function must return a tuple of to dictionaries containing the same keys. The first dictionary contains assembly-
3D-configurations . The second dictionary contains the slice-configurations .
Anassembly-3D-configurations is a list of extruded and placed figures. Each item of the list contains:
• 2D-figure label: defined by the function ABC_figures()
• zero_x, zero_y: the reference coordinates of the 2D-figure
• size_x, size_y: the reference sizes of the 2D-figure
• size-z: the height of extrusion
• i,x,y,z-flip: the flip of the extruded part
• xy,yx,xz,zx,yz,zy-orientation: the orientation of the extruded part
• translation-xyz: the final translation
For more details, read the chapter Plank Positioning Details.
Theslice-configurations is used by write_assembly_brep() to generate several 2D-cuts of the 3D-assembly. A slice-
configurations is defined by:
• size-x, size-y, size-z: the reference dimension of the 3D-assembly
• zero-x, zero-y, zero-z: the reference coordinates of the 3D assembly
• slice-xy-list: the list of z-coordinates to cut the assembly in the xy-plan
• slice-xz-list: the list of y-coordinates to cut the assembly in the xz-plan
• slice-yz-list: the list of x-coordinates to cut the assembly in the yz-plan
70 Chapter 11. Creating a Cnc25D Design
Cnc25D Documentation, Release 0.1.11
11.2.5 ABC_3d_freecad_construction(c)
defA_freecad_construction(c):
r_3dobj = Part.makeCompound()
return(r_3dobj)
defABC_3d_freecad_construction(c):
r_fc_obj_f = {}
r_slice = {}
#
r_fc_obj_f['A_3dobj'] = A_freecad_construction
r_slice['A_3dobj'] = []
###
return((r_fc_obj_f, r_slice))
The function ABC_3d_freecad_construction() is similar to the function ABC_3d() but instead of recording assembly-
3D-configurations , it points to freecad_construction functions. These functions can access directly to the FreeCAD
API. They provide more possibilities than the compact but restricted format assembly-3D-configurations .
The function freecad_construction() must use as argument the constraint dictionary and must return a FreeCAD object.
11.2.6 ABC_info()
defABC_info(c):
r_txt = """
constraint_A: {:0.3f}
""".format(c['constraint_A'])
return(r_txt)
The function ABC_info() generates a string that is used as log during the design construction. The function must use
as argument the constraint dictionary and must return a string .
11.2.7 ABC_simulations()
defsimulation_A(c):
print("use the cnc25d_api to test what you want")
return(1)
defABC_simulations():
r_sim = {}
r_sim['sim_A'] = simulation_A
return(r_sim)
The function ABC_simulations() generates a dictionary containing pointers to simulation functions. The function
doesn’t need any argument and return the function pointer dictionary. Actually, the function could be replaced by a
function pointer dictionary. For aesthetic, I prefer using a function without argument.
The simulation function must use as argument the constraint dictionary . The return value of this function is irrelevant.
11.2.8 ABC_self_test()
defABC_self_test():
r_tests = [
('test_A', '--constraint_A 7.0 --constraint_B 5.0'),
11.2. Design Functions 71
Cnc25D Documentation, Release 0.1.11
('test_B', '--constraint_A 3.0 --constraint_B 9.0')]
return(r_tests)
The function ABC_self_test() generates a list of 2-tuple containing sets of constraint used to test the design in general
or corner cases. The function doesn’t need any argument and could be replaced by a simple list. Each item of the list
is a test case. The two strings of a test-case are the test-name and the constraint-values at the CLI (command-line-
interface) format.
11.2.9 ABC_cli_return_type()
defABC_cli_return_type(c):
return(r_cli)
The function ABC_cli_return_type() generates the value returned by the method cli(). The function must use as
argument the constraint dictionary . It returns what you want the method cli() must return. This function is obsolete
and should not be used anymore.
11.3 Design Setup
class ABC (bare_design):
def__init__(self, constraint={}):
self.design_setup( # function to setup a cnc25d design
s_design_name = "ABC_design", # mandatory string, used to enhance information and error messages
f_constraint_constructor = ABC_constraint_constructor, # mandatory function, set the design constraint
f_constraint_check = ABC_constraint_check, # highly recommended function to check the design constraint
f_2d_constructor = ABC_figures, # function that generates a dictionary that contains 2D-figures
d_2d_simulation = ABC_simulations(), # dictionary to functions running simulations
f_3d_constructor = ABC_3d, # function that generates a dictionary that contains 3D-assembly
f_3d_freecad_constructor = ABC_3d_freecad_construction, # function that generates a dictionary that contains 3D-freecad-functions
f_info = ABC_info, # function that generates a string
l_display_figure_list = [], # list of the 2D-figures to be displayed in a Tk-window
s_default_simulation = "", # simulation string name, set the default action to simulation instead of 2D-figure-display
l_2d_figure_file_list = [], # 2D-figures to be written in SVG or DXF files
l_3d_figure_file_list = [], # 2D-figures to be written in Brep files
l_3d_conf_file_list = [], # 3D-assembly-configurations to be written in Brep files
l_3d_freecad_file_list = [], # 3D-freecad-construction to be written in Brep files
f_cli_return_type = [], # obsolete function that defines the return value of the method cli()
l_self_test_list = ABC_self_test()) # list of tests to be run to check the design
self.apply_constraint(constraint) # optional but quiet convenient
If you don’t want to use one or several settings, set them to None or comment the line. Concerning the list, usually an
empty list means all available 2D-figures or 3D-assembly. None means nothing.
11.4 Design Usage
my_abc = ABC(ABC_constraint)
my_abc.outline_display() # display the 2D-figures of the list l_display_figure_list in Tk-windows
my_abc.write_figure_svg("test_output/abc_macro") # write in SVG files the 2D-figures of the list l_2d_figure_file_list
my_abc.write_figure_dxf("test_output/abc_macro") # write in DXF files the 2D-figures of the list l_2d_figure_file_list
my_abc.write_figure_brep("test_output/abc_macro") # write in Brep files the extruded 2D-figures of the list l_3d_figure_file_list
my_abc.write_assembly_brep("test_output/abc_macro") # write in Brep files the 3D-assembly of the list l_3d_conf_file_list
my_abc.write_freecad_brep("test_output/abc_macro") # write in Brep files the 3D-assembly of the list l_3d_freecad_file_list
72 Chapter 11. Creating a Cnc25D Design
Cnc25D Documentation, Release 0.1.11
#my_abc.run_simulation("sim_A") # run the simulation
my_abc.view_design_configuration() # display information of the design setup. Useful when you want to reuse an old design
my_abc.run_self_test("") # run the test case of the list l_self_test_list
my_abc.cli("--output_file_basename test_output/my_abc.dxf") # Warning: all constraint values are reset to their default values
if(cnc25d_api.interpretor_is_freecad()): # check if the interpretor is freecad
Part.show(my_abc.get_fc_obj_3dconf('A_3dconf')) # display the 3D object corresponding to the 3D-assembly-configuration abc_3dconf1
my_fig = my_abc.get_A_figure('A_figure') # get the figure A_figure at the A-format
my_fig = my_abc.get_B_figure('A_figure') # get the figure A_figure at the B-format
my_fc_obj = my_abc.get_fc_obj_3dconf('A_3dconf') # get the FreeCAD object the 3D-assembly-configuration A_3dconf
my_fc_obj = my_abc.get_fc_obj_function('A_3dobj') # get the FreeCAD object the 3D-freecad-construction A_3dobj
my_txt = my_abc.info() # get text information about the design ABC
my_constraint = my_abc.get_constraint() # get a dictionary containing all set and internal constraint of the ABC design
my_abc.apply_constraint(my_constraint) # change the constraint of the ABC design my_abc with checking the dictionary set as argument
my_abc.apply_external_constraint(my_constraint) # change the constraint of the ABC design my_abc without checking the dictionary set as argument
11.5 Internal Methods
The internal methods can be used in some advanced cases.
(figs, heights) = my_abc.apply_2d_constructor() # generates and returns the 2D-figures according to the current constraint
(assembly_3dconfs, slice_confs) = my_abc.apply_3d_constructor() # generates and returns the 3D-assembly-configurations according to the current constraint
(freecad_function_pts, slice_confs) = my_abc.apply_3d_freecad_constructor() # generates and returns the 3D-freecad-function-pointers according to the current constraint
my_abc.set_design_name(s_design_name) # overwrite the design name
my_abc.set_constraint_constructor(f_constraint_constructor) # overwrite the function that defines the design constraint
my_abc.set_constraint_check(f_constraint_check) # overwrite the function that checks the design constraint
my_abc.set_2d_constructor(f_2d_constructor) # overwrite the function that generates the 2D-figures
my_abc.set_2d_simulation(d_2d_simulation) # overwrite the dictionary that points to the simulation functions
my_abc.set_3d_constructor(f_3d_constructor) # overwrite the function that generates the 3D-assembly-configurations
my_abc.set_3d_freecad_constructor(f_3d_freecad_constructor) # overwrite the function that points to the freecad-3d-construction functions
my_abc.set_info(f_info) # overwrite the function that generates the information string
my_abc.set_display_figure_list(l_display_figure_list) # overwrite the list of the displayed 2D-figures
my_abc.set_default_simulation(s_default_simulation) # overwrite the default action as simulation. If set to the empty string, display 2D-figures is the default action.
my_abc.set_2d_figure_file_list(l_2d_figure_file_list) # overwrite the list of the 2D-figures to be written in SVG or DXF files
my_abc.set_3d_figure_file_list(l_3d_figure_file_list) # overwrite the list of the 2D-figures to be written in Brep files
my_abc.set_3d_conf_file_list(l_3d_conf_file_list) # overwrite the list of the 3D-assembly-configurations to be written in Brep files
my_abc.set_3d_freecad_file_list(l_3d_freecad_file_list) # overwrite the list of the 3D-freecad-function-construction to be written in Brep files
my_abc.set_cli_return_type(f_cli_return_type) # overwrite the function to generate the return value of the cli() method
my_abc.set_self_test(l_self_test_list) # overwrite the list of tests
11.5. Internal Methods 73
Cnc25D Documentation, Release 0.1.11
74 Chapter 11. Creating a Cnc25D Design
CHAPTER 12
Cnc25D Designs
12.1 Cnc25D design introduction
In addition to the Cnc25D API functions, the Cnc25D Python package includes also several parametric de-
signs. The design parameters are called constraints and are set via a dictionary. Most of the constraints are not
mandatory and if you don’t set some constraints, their default values are used. Use the files provided by the
cnc25d_example_generator.py as template to generate one of the Cnc25D designs . Depending on the constraints
output_file_basename andreturn_type , you can generate .dxf,.svg or.brep files or include the Cnc25D Design- as
*Part-object in your FreeCAD macro. For more information about how to use the Cnc25D designs read the section
Cnc25D Design Details.
12.2 Cnc25D design list
• Box Wood Frame Design
• Gear Profile Function
• Gearwheel Design
• Gearring Design
• Gearbar Design
• Split-gearwheel Design
• Epicyclic Gearing Design
• Axle Lid Design
• Motor Lid Design
• Bell Design
• Bagel Design
• Bell Bagel Assembly
• Crest Design
• Cross_Cube Design
• Gimbal Design
75
Cnc25D Documentation, Release 0.1.11
12.3 Cnc25D design overview
12.3.1 Box_wood_frame
The Box Wood Frame Design is a piece of furniture. Its particularity is that its top-shape and its bottom-shape are
complementary. So, you can pile-up your boxes.
12.3.2 Gear_profile
The Gear Profile Function generates the gear-profile outline. You can also simulate this outline with a second gear-
profile to make sure it works as you wish it. The gear-profile itself is not a 3D part but a simple outline. You can use
this outline to create a complete 3D part.
76 Chapter 12. Cnc25D Designs
Cnc25D Documentation, Release 0.1.11
12.3.3 Gearwheel
The Gearwheel Design is a complete gearwheel part (a.k.a. spur). You can specify the number of gear-teeth, the
number of legs, the size of the axle and much more.
12.3. Cnc25D design overview 77
Cnc25D Documentation, Release 0.1.11
12.3.4 Gearring
The Gearring Design is a complete gearring part (a.k.a. annulus). You can use it to create your epicyclic gear system.
78 Chapter 12. Cnc25D Designs
Cnc25D Documentation, Release 0.1.11
12.3.5 Gearbar
The Gearbar Design is a complete rack part.
12.3. Cnc25D design overview 79
Cnc25D Documentation, Release 0.1.11
12.3.6 Split_gearwheel
The Split-gearwheel Design generates several 3D parts that can be assembled to create a complete gearwheel. The
split gearwheel lets you make large gearwheel by making smaller sub parts and then assembling them.
80 Chapter 12. Cnc25D Designs
Cnc25D Documentation, Release 0.1.11
12.3.7 Epicyclic_gearing
The Epicyclic Gearing Design is a complete epicyclic gearing system. You can use it to increase the torque (and
decreasing the rotation speed).
12.3.8 Axle_lid
The Axle Lid Design is a axle-lid design kit. You can use it to complete the epicyclic_gearing design.
12.3. Cnc25D design overview 81
Cnc25D Documentation, Release 0.1.11
12.3.9 Motor_lid
The Motor Lid Design is an extension of the axle-lid design kit to mount an electrical motor. You can use it to complete
the epicyclic_gearing design.
12.3.10 Bell
The Bell Design is the extremity of a gimbal system. You can complete is with a bagel and a cross_cube to get a
complete gimbal system.
82 Chapter 12. Cnc25D Designs
Cnc25D Documentation, Release 0.1.11
12.3.11 Bagel
The Bagel Design is the axle-guidance of the bellpiece.
12.3. Cnc25D design overview 83
Cnc25D Documentation, Release 0.1.11
12.3.12 Bell_bagel_assembly
The Bell Bagel Assembly is the assembly of a bellpiece and two bagels .
12.3.13 Crest
The Crest Design is an optional part for the cross_cube piece.
84 Chapter 12. Cnc25D Designs
Cnc25D Documentation, Release 0.1.11
12.3.14 Cross_cube
The Cross_Cube Design is the two-axle-join of agimbal system.
12.3.15 Gimbal
The Gimbal Design is a mechanism with two angles as degree of freedom.
12.3. Cnc25D design overview 85
Cnc25D Documentation, Release 0.1.11
86 Chapter 12. Cnc25D Designs
CHAPTER 13
Cnc25D Design Details
13.1 Cnc25D design usage
13.1.1 From the source repository
Using the design module
Go to the Cnc25D source repository and execute the design script with or without arguments:
> cd Cnc25D
> python cnc25D/XYZDesign.py
or:
> python cnc25D/XYZDesign.py --param_A 50.0 --param_C 30.0
Without arguments, the default command line is used.
When you don’t use argument, you can also use freecad instead of python
> freecad cnc25D/XYZDesign.py
With freecad , you can not choose the arguments on the command line because of the conflict with the freecad argument
parser. So you have to change the default command line at the end of the design script:
if__name__ == "__main__":
FreeCAD.Console.PrintMessage("XYZDesign.py says hello! \n")
my_xyz = XYZDesign_cli("--param_A 6.0 --param_B 13.0 --return_type freecad_object".split()) # default command line arguments: choose here you argument to run the script with freecad
try:# depending on xyz_c['return_type'] it might be or not a freecad_object
Part.show(my_xyz)
print("freecad_object returned")
except:
pass
#print("return_type is not a freecad-object")
The argument –return_type freecad_object lets you visualizing the result in FreeCAD.
Using the test-macro
Go to the Cnc25D source repository and execute the test-macro without argument:
87
Cnc25D Documentation, Release 0.1.11
> cd Cnc25D
> python cnc25D/tests/XYZDesign_macro.py
or:
> freecad cnc25D/tests/XYZDesign_macro.py
You can use those test-macro scripts as FreeCAD macro and run them from the FreeCAD GUI. Make sure the test-
macro script returns a freecad_object :
xyz_x['return_type'] = 'freecad_object'
13.1.2 From the installed Cnc25D package
After installing the Cnc25D Python package , run cnc25d_example_generator.py to get the Cnc25D example scripts .
These Cnc25D example scripts are actually a copy of the previous test-macros . You can execute them without argu-
ment with python orfreecad :
> cd where/I/have/generated/the/Cnc25D/example/scripts
> python eg05_XYZDesign_example.py
or:
> freecad eg05_XYZDesign_example.py
Like with the test-macro script , make sure the script returns a freecad_object . If not, edit your script and set the
following constraint:
xyz_x['return_type'] = 'freecad_object'
Your script can also be used as a FreeCAD macro and can be called from the FreeCAD GUI .
13.2 Cnc25D design implementation structure
Template of a Cnc25D design script:
################################################################
# import
################################################################
import cnc25d_api
cnc25d_api.importing_freecad()
import math
import sys ,argparse
import Part
################################################################
# XYZDesign dictionary-constraint-arguments default values
################################################################
defXYZDesign_dictionary_init():
""" create and initiate a XYZDesign_dictionary with the default value
"""
r_xyzd = {}
r_xyzd['param_A'] = 5.0
r_xyzd['param_B'] = 10.0
88 Chapter 13. Cnc25D Design Details
Cnc25D Documentation, Release 0.1.11
r_xyzd['param_C'] = 0.0
r_xyzd['return_type'] = 'int_status' # possible values: 'int_status', 'cnc25d_figure', 'freecad_object'
# ...
return(r_xyzd)
################################################################
# XYZDesign argparse
################################################################
defXYZDesign_add_argument(ai_parser):
"""
Add arguments relative to the XYZDesign
This function intends to be used by the XYZDesign_cli and XYZDesign_self_test
"""
r_parser = ai_parser
r_parser.add_argument('--param_A','--pa', action='store', type=float, default=5.0, dest='sw_param_A',
help="Set the param_A. Default: 5.0")
r_parser.add_argument('--param_B','--pb', action='store', type=float, default=10.0, dest='sw_param_B',
help="Set the param_B. Default: 10.0")
r_parser.add_argument('--param_C','--pc', action='store', type=float, default=0.0, dest='sw_param_C',
help="Set the param_C. If equal to 0.0, the default value is computed. Default: 0.0")
# ...
return(r_parser)
################################################################
# the most important function to be used in other scripts
################################################################
defXYZDesign(ai_constraints):
"""
The main function of the script.
It generates a XYZDesign according to the constraint-arguments
"""
### check the dictionary-arguments ai_constraints
xyzdi = XYZDesign_dictionary_init()
xyz_c = xyzdi.copy()
xyz_c.update(ai_constraints)
if(len(xyz_c.viewkeys() & xyzdi.viewkeys()) != len(xyz_c.viewkeys() | xyzdi.viewkeys())): # check if the dictionary xyz_c has exactly all the keys compare to XYZDesign_dictionary_init()
print("ERR157: Error, xyz_c has too much entries as {:s} or missing entries as {:s}".format(xyz_c.viewkeys() - xyzdi.viewkeys(), xyzdi.viewkeys() - xyz_c.viewkeys()))
sys.exit(2)
### dynamic default value
if(ai_constraints['param_C']==0):
xyz_c['param_C'] = xyz_c['param_B']/5
### generate the XYZDesign figure
# ...
# display with Tkinter
if(xyz_c['tkinter_view']):
print(XYZDesign_parameter_info)
cnc25d_api.figure_simple_display(xyz_figure, xyz_figure_overlay, XYZDesign_parameter_info)
# generate output file
cnc25d_api.generate_output_file(xyz_figure, xyz_c['output_file_basename'], xyz_c['XYZDesign_height'], XYZDesign_parameter_info)
#### return
if(xyz_c['return_type']=='int_status'):
r_xyz = 1
elif(xyz_c['return_type']=='cnc25d_figure'):
13.2. Cnc25D design implementation structure 89
Cnc25D Documentation, Release 0.1.11
r_xyz = xyz_figure
elif(xyz_c['return_type']=='freecad_object'):
r_xyz = cnc25d_api.figure_to_freecad_25d_part(xyz_figure, xyz_c['XYZDesign_height'])
else:
print("ERR508: Error the return_type {:s} is unknown".format(xyz_c['return_type']))
sys.exit(2)
return(r_xyz)
################################################################
# XYZDesign wrapper dance
################################################################
defXYZDesign_argparse_to_dictionary(ai_xyz_args):
""" convert a XYZDesign_argparse into a XYZDesign_dictionary
"""
r_xyzd = {}
r_xyzd['param_A'] = ai_xyz_args.sw_param_A
r_xyzd['param_B'] = ai_xyz_args.sw_param_B
r_xyzd['param_C'] = ai_xyz_args.sw_param_c
#### return
return(r_xyzd)
defXYZDesign_argparse_wrapper(ai_xyz_args, ai_args_in_txt=""):
"""
wrapper function of XYZDesign() to call it using the XYZDesign_parser.
XYZDesign_parser is mostly used for debug and non-regression tests.
"""
# view the XYZDesign with Tkinter as default action
tkinter_view = True
if(ai_xyz_args.sw_simulation_enable or(ai_xyz_args.sw_output_file_basename!='')):
tkinter_view = False
# wrapper
xyzd = XYZDesign_argparse_to_dictionary(ai_xyz_args)
xyzd['args_in_txt'] = ai_args_in_txt
xyzd['tkinter_view'] = tkinter_view
#xyzd['return_type'] = 'int_status'
r_xyz = XYZDesign(xyzd)
return(r_xyz)
################################################################
# self test
################################################################
defXYZDesign_self_test():
"""
This is the non-regression test of XYZDesign.
"""
test_case_switch = [
["Test_A" , "--param_A 20.0"],
["Test B" , "--param_B 15.0 --param_C 5.0"],
["Advanced Test C" , "--param_A 10.0 --param_B 8.0 --param_C 15.0"]]
#print("dbg741: len(test_case_switch):", len(test_case_switch))
XYZDesign_parser = argparse.ArgumentParser(description='Command line interface for the function XYZDesign().')
XYZDesign_parser = XYZDesign_add_argument(XYZDesign_parser)
XYZDesign_parser = cnc25d_api.generate_output_file_add_argument(XYZDesign_parser, 1)
foriinrange(len(test_case_switch)):
l_test_switch = test_case_switch[i][1]
print("{:2d} test case: '{:s}' \nwith switch: {:s}".format(i, test_case_switch[i][0], l_test_switch))
90 Chapter 13. Cnc25D Design Details
Cnc25D Documentation, Release 0.1.11
l_args = l_test_switch.split()
#print("dbg414: l_args:", l_args)
st_args = XYZDesign_parser.parse_args(l_args)
r_xyzst = XYZDesign_argparse_wrapper(st_args)
return(r_xyzst)
################################################################
# XYZDesign command line interface
################################################################
defXYZDesign_cli(ai_args=None):
""" command line interface of XYZDesign.py when it is used in standalone
"""
# XYZDesign parser
XYZDesign_parser = argparse.ArgumentParser(description='Command line interface for the function XYZDesign().')
XYZDesign_parser = XYZDesign_add_argument(XYZDesign_parser)
XYZDesign_parser = cnc25d_api.generate_output_file_add_argument(XYZDesign_parser, 1)
# switch for self_test
XYZDesign_parser.add_argument('--run_test_enable','--rst', action='store_true', default=False, dest='sw_run_self_test',
help='Generate several corner cases of parameter sets.')
effective_args = cnc25d_api.get_effective_args(ai_args)
effective_args_in_txt = "XYZDesign arguments: " + ' '.join(effective_args)
xyz_args = XYZDesign_parser.parse_args(effective_args)
print("dbg111: start making XYZDesign")
if(xyz_args.sw_run_self_test):
r_xyz = XYZDesign_self_test()
else:
r_xyz = XYZDesign_argparse_wrapper(xyz_args, effective_args_in_txt)
print("dbg999: end of script")
return(r_xyz)
################################################################
# main
################################################################
if__name__ == "__main__":
FreeCAD.Console.PrintMessage("XYZDesign.py says hello! \n")
my_xyz = XYZDesign_cli("--param_A 6.0 --param_B 13.0".split())
try:# depending on xyz_c['return_type'] it might be or not a freecad_object
Part.show(my_xyz)
print("freecad_object returned")
except:
pass
#print("return_type is not a freecad-object")
13.2. Cnc25D design implementation structure 91
Cnc25D Documentation, Release 0.1.11
92 Chapter 13. Cnc25D Design Details
CHAPTER 14
Box Wood Frame Design
14.1 Box wood frame presentation
Box wood frame is the name of this piece of furniture:
93
Cnc25D Documentation, Release 0.1.11
Its main characteristic is its top and bottom fittings that lets pile-up a Box wood frame over an other:
94 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
This pile-up functionality has several goals:
14.1. Box wood frame presentation 95
Cnc25D Documentation, Release 0.1.11
• split the manufacturing of large wardrobe into several small modules
• make easier the move of furniture
• be part of the structure of straw houses .
The Box wood frame design uses complex and precise recessed fittings to assemble the planks. So the cuts of the
planks must be done with a CNC or with a manual wood router and templates. Then the planks can be glued together.
14.2 Box wood frame creation
After installing FreeCAD and the Python package Cnc25D as described at the paragraph Cnc25D Installation , run the
executable cnc25d_example_generator.py in the directory where you want to create the Box wood frame :
> cd /directory/where/I/want/to/create/a/box/wood/frame/
> cnc25d_example_generator.py # answer 'y' or 'yes' when it asks you to generate the example box_wood_frame_example.py
> python box_wood_frame_example.py
After several minutes of computation, you get plenty of DXF and STL files that let you manufacture a Box wood frame .
Read the text_report.txt file to get further information on your generated Box wood frame and on the descriptions of
the other generated files. Use LibreCAD to view the DXF files. Use MeshLAB to view the STL files:
> librecad bwf37_assembly_with_amplified_cut.dxf
> meshlab # import bwf36_assembly_with_amplified_cut.stl
> less bwf49_text_report.txt
Your Box wood frame has been generated with the default parameters. You may want to changes these parameter
values to adapt them to your need. Edit the file box_wood_frame_example.py , change some parameters values, save
your changes and run again:
> python box_wood_frame_example.py
Now you get the Box wood frame design files according to your parameters.
14.3 Box wood frame parameters
14.3.1 bwf_box_width
bwf_box_width default value : 400.0
96 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.2 bwf_box_depth
bwf_box_depth default value : 400.0
14.3. Box wood frame parameters 97
Cnc25D Documentation, Release 0.1.11
recommendation: Keep bwf_box_depth = bwf_box_width to get more pile up possibilities.
14.3.3 bwf_box_height
bwf_box_height default value : 400.0
14.3.4 bwf_fitting_height
bwf_fitting_height default value : 30.0
98 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.5 bwf_h_plank_width
bwf_h_plank_width default value : 50.0
14.3. Box wood frame parameters 99
Cnc25D Documentation, Release 0.1.11
14.3.6 bwf_v_plank_width
bwf_v_plank_width default value : 30.0
100 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.7 bwf_plank_height
bwf_plank_height default value : 20.0
14.3. Box wood frame parameters 101
Cnc25D Documentation, Release 0.1.11
14.3.8 bwf_d_plank_width
bwf_d_plank_width default value : 30.0
102 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.9 bwf_d_plank_height
bwf_d_plank_height default value : 10.0
14.3. Box wood frame parameters 103
Cnc25D Documentation, Release 0.1.11
14.3.10 bwf_crenel_depth
bwf_crenel_depth default value : 5.0
104 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.11 bwf_wall_diagonal_size
bwf_wall_diagonal_size default value : 50.0
14.3. Box wood frame parameters 105
Cnc25D Documentation, Release 0.1.11
14.3.12 bwf_tobo_diagonal_size
bwf_tobo_diagonal_size default value : 100.0
106 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.13 bwf_diagonal_lining_top_height
bwf_diagonal_lining_top_height default value : 20.0
14.3. Box wood frame parameters 107
Cnc25D Documentation, Release 0.1.11
14.3.14 bwf_diagonal_lining_bottom_height
bwf_diagonal_lining_bottom_height default value : 20.0
14.3.15 bwf_module_width
bwf_module_width default value : 1
bwf_module_width = 1
108 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
bwf_module_width = 2
14.3. Box wood frame parameters 109
Cnc25D Documentation, Release 0.1.11
bwf_module_width = 3
110 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
bwf_module_width = 5
14.3. Box wood frame parameters 111
Cnc25D Documentation, Release 0.1.11
14.3.16 bwf_router_bit_radius
bwf_router_bit_radius default value : 2.0
112 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.3.17 bwf_cutting_extra
bwf_cutting_extra default value : 2.0
14.3. Box wood frame parameters 113
Cnc25D Documentation, Release 0.1.11
Note: The parameter bwf_cutting_extra doesn’t affect the cnc cutting plan. It just help to see the junction between the
plans.
14.3.18 bwf_slab_thickness
bwf_slab_thickness default value : 5.0
The slabs are the skin of your box wood frame . Set the slab thickness to the available plywood thickness of your
supplier. Try to keep this relation:
bwf_plank_height > bwf_d_plank_height + bwf_slab_thickness
14.3.19 bwf_output_file_basename
bwf_output_file_basename default value : “”
Set the parameter bwf_output_file_basename to a not-empty string if you want to generate the output files. The
box_wood_frame_example.py generates many files. These files can be generated in a directory or be identified by a
common basename. The generated text file text_report.txt described all generated files.
Output file base name example:
bwf_output_file_basename = "my_output_dir/"
bwf_output_file_basename = "my_output_dir/my_output_basename"
bwf_output_file_basename = "my_output_basename"
114 Chapter 14. Box Wood Frame Design
Cnc25D Documentation, Release 0.1.11
14.4 Box wood frame conception
The notes relative to process of conception of the Box wood frame are available in the chapter Box Wood Frame
Conception Details.
14.5 Box wood frame manufacturing
As you can see in the design files, the outline of the planks are quiet complex. Those many recessed fittings enable a
solid assembly. To cut the planks precisely according to design files you have two methods:
• Use a 3-axis CNC
• Use a manual wood router and templates for each type of planks.
Notice that you need a CNC to make the templates.
The CNC method is well adapted when you want just few pieces of Box wood frame . The planks are cut in large
plywood slabs (long and wide). This increase the final price of a Box wood frame module.
After getting the templates fitting your Box wood frame parameters, you can use a manual route to duplicate the planks.
As raw material you can use solid wood plank (long and narrow). This is cheaper and provide a stronger assembly.
14.4. Box wood frame conception 115
Cnc25D Documentation, Release 0.1.11
116 Chapter 14. Box Wood Frame Design
CHAPTER 15
Box Wood Frame Conception Details
15.1 Design purpose
The Box_Wood_Frame design is a solid and cost effective piece of furniture that can be piled up.
The pile-up feature is useful for:
• rearranging interior
• transporting the pieces of furniture
• moving accommodation
• And also, maybe, building straw house
• it lets make big pieces of furniture out of small pieces of material
• the conception is also cut in several small problematics
• the big pieces of furniture can be easily dismount, transport and remount
The frame is made out of solid wood planks. The faces can then be closed with light plywood.
117
Cnc25D Documentation, Release 0.1.11
A module corresponds to one or several box of the grid. We focus on the concatenation of box along the x axis. N is
the number of concatenated box (along the x axis).
15.2 Construction method
The planks are fixed by crenel and glue.
118 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.3 Design proposal
Wood frame plank list:
• horizontal plank: 20x60
• vertical plank: 20x30
• diagonal: 10x30 (thiner to give space for the face plywood)
15.4 Box wood frame parameters
A module is defined by:
• The box dimension (w*d*h): 300*300*300
• The number of aggregated box: N*1*1
N is the length of the module. It is a number of boxes.
15.3. Design proposal 119
Cnc25D Documentation, Release 0.1.11
120 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.5 Plank outline description
Q is the number of required planks to build one module. It can depends on N, the length of the module.
15.5.1 plank01_xz_bottom
Q = 2
15.5. Plank outline description 121
Cnc25D Documentation, Release 0.1.11
15.5.2 plank02_xz_top
Q = 2
122 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.5.3 plank03_yz_bottom
Q = 2
15.5.4 plank04_yz_top
Q = 2
15.5. Plank outline description 123
Cnc25D Documentation, Release 0.1.11
15.5.5 plank05_z_side
Q = 2*(3+N)
15.5.6 plank06_zx_middle
Q = 2*(N-1)
124 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.5.7 plank07_wall_diagonal
Q = 4*(1+3*N)
15.5.8 plank08_tobo_diagonal
Q = 8*N
15.5.9 hole_cover
Q = 8*(N+1)
15.5. Plank outline description 125
Cnc25D Documentation, Release 0.1.11
The plank09_hole_cover has an aesthetic functionality.
15.6 Diagonal plank reorientation
The planks are positioned in the cuboid assembly with the place_plank() function. To position the diagonal planks
with this function, the diagonal planks must first be rotated of 45 degrees and affected with virtual length and width
corresponding to the assimilated straight plank.
126 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.7 Slab outline description
15.7.1 slab51_tobo_single
Q = 2 if (N==1) else 0
15.7.2 slab52_tobo_side
Q = 4 if (N>1) else 0
Same outline as slab51_tobo_single except that the length is:
box_width - 1.5 *plank_height
15.7.3 slab53_tobo_middle
Q = 2*(N-2) if (N>2) else 0
Same outline as slab51_tobo_single except that the length is:
box_width - 1.0 *plank_height
15.7.4 slab54_side_left_right
Q = 2
15.7. Slab outline description 127
Cnc25D Documentation, Release 0.1.11
15.7.5 slab55_side_rear_single
Q = 1 if (N==1) else 0
128 Chapter 15. Box Wood Frame Conception Details
Cnc25D Documentation, Release 0.1.11
15.7.6 slab56_side_rear_side
Q = 2 if (N>1) else 0
Same outline as slab55_side_rear_single except that the length is:
box_width - 1.5 *plank_v_width
15.7.7 slab57_side_rear_middle
Q = N-2 if (N>2) else 0
Same outline as slab55_side_rear_single except that the length is:
box_width - 1.0 *plank_v_width
15.7.8 slab58_front
Q = 4*N
15.7. Slab outline description 129
Cnc25D Documentation, Release 0.1.11
130 Chapter 15. Box Wood Frame Conception Details
CHAPTER 16
Gear Profile Function
Thegear_profile() function generates a format-B outline of a gear profile with the following features:
• the gear-tooth-profile ensures a constant line of action and a constant speed ratio
• the gear-profile (including the gear hollow) is makable by a 3-axis CNC
• a gear system with two parts can be simulated with the Tkinter GUI
• very configurable: asymmetrical teeth are possible
• active tooth profile made out of arcs and with a continuous tangent inclination
• optional portion of gear to make split gearwheel
131
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible gear_profiles that can be gear_profile() , run:
> python gear_profile.py --run_self_test
16.1 Gear high-level parameters
The gear high-level parameters let describe with a reduce number of integers and floats a complete gear system. Some
of these high-level are depending on each others.
132 Chapter 16. Gear Profile Function
Cnc25D Documentation, Release 0.1.11
16.1.1 Gear types
16.1. Gear high-level parameters 133
Cnc25D Documentation, Release 0.1.11
16.1.2 Gearwheel high-level parameters
134 Chapter 16. Gear Profile Function
Cnc25D Documentation, Release 0.1.11
16.1.3 Gearbar high-level parameters
16.2 gear_profile() function arguments list
The arguments of the function gear_profile() are not directly the high-level gear parameters but constraints used to
deduce the high-level gear parameters.
The switches of the module gear_profile.py are directly connected to the function gear_profile() . Use the module
gear_profile.py to experiment the gear_profile() arguments. Notice that -hand–run_self_test are not arguments of
gear_profile() .
usage: gear_profile.py [-h] [--gear_type SW_GEAR_TYPE]
[--gear_tooth_nb SW_GEAR_TOOTH_NB]
[--gear_module SW_GEAR_MODULE]
[--gear_primitive_diameter SW_GEAR_PRIMITIVE_DIAMETER]
[--gear_addendum_dedendum_parity SW_GEAR_ADDENDUM_DEDENDUM_PARITY]
[--gear_tooth_half_height SW_GEAR_TOOTH_HALF_HEIGHT]
[--gear_addendum_height_pourcentage SW_GEAR_ADDENDUM_HEIGHT_POURCENTAGE]
[--gear_dedendum_height_pourcentage SW_GEAR_DEDENDUM_HEIGHT_POURCENTAGE]
[--gear_hollow_height_pourcentage SW_GEAR_HOLLOW_HEIGHT_POURCENTAGE]
[--gear_router_bit_radius SW_GEAR_ROUTER_BIT_RADIUS]
[--gear_base_diameter SW_GEAR_BASE_DIAMETER]
[--gear_force_angle SW_GEAR_FORCE_ANGLE]
[--gear_tooth_resolution SW_GEAR_TOOTH_RESOLUTION]
[--gear_skin_thickness SW_GEAR_SKIN_THICKNESS]
[--gear_base_diameter_n SW_GEAR_BASE_DIAMETER_N]
[--gear_force_angle_n SW_GEAR_FORCE_ANGLE_N]
[--gear_tooth_resolution_n SW_GEAR_TOOTH_RESOLUTION_N]
[--gear_skin_thickness_n SW_GEAR_SKIN_THICKNESS_N]
[--second_gear_type SW_SECOND_GEAR_TYPE]
16.2. gear_profile() function arguments list 135
Cnc25D Documentation, Release 0.1.11
[--second_gear_tooth_nb SW_SECOND_GEAR_TOOTH_NB]
[--second_gear_primitive_diameter SW_SECOND_GEAR_PRIMITIVE_DIAMETER]
[--second_gear_addendum_dedendum_parity SW_SECOND_GEAR_ADDENDUM_DEDENDUM_PARITY]
[--second_gear_tooth_half_height SW_SECOND_GEAR_TOOTH_HALF_HEIGHT]
[--second_gear_addendum_height_pourcentage SW_SECOND_GEAR_ADDENDUM_HEIGHT_POURCENTAGE]
[--second_gear_dedendum_height_pourcentage SW_SECOND_GEAR_DEDENDUM_HEIGHT_POURCENTAGE]
[--second_gear_hollow_height_pourcentage SW_SECOND_GEAR_HOLLOW_HEIGHT_POURCENTAGE]
[--second_gear_router_bit_radius SW_SECOND_GEAR_ROUTER_BIT_RADIUS]
[--second_gear_base_diameter SW_SECOND_GEAR_BASE_DIAMETER]
[--second_gear_tooth_resolution SW_SECOND_GEAR_TOOTH_RESOLUTION]
[--second_gear_skin_thickness SW_SECOND_GEAR_SKIN_THICKNESS]
[--second_gear_base_diameter_n SW_SECOND_GEAR_BASE_DIAMETER_N]
[--second_gear_tooth_resolution_n SW_SECOND_GEAR_TOOTH_RESOLUTION_N]
[--second_gear_skin_thickness_n SW_SECOND_GEAR_SKIN_THICKNESS_N]
[--gearbar_slope SW_GEARBAR_SLOPE]
[--gearbar_slope_n SW_GEARBAR_SLOPE_N]
[--center_position_x SW_CENTER_POSITION_X]
[--center_position_y SW_CENTER_POSITION_Y]
[--gear_initial_angle SW_GEAR_INITIAL_ANGLE]
[--second_gear_position_angle SW_SECOND_GEAR_POSITION_ANGLE]
[--second_gear_additional_axis_length SW_SECOND_GEAR_ADDITIONAL_AXIS_LENGTH]
[--cut_portion SW_CUT_PORTION SW_CUT_PORTION SW_CUT_PORTION]
[--gear_profile_height SW_GEAR_PROFILE_HEIGHT]
[--simulation_enable]
[--output_file_basename SW_OUTPUT_FILE_BASENAME]
[--run_self_test]
Command line interface for the function gear_profile().
optional arguments:
-h, --help show this help message and exit
--gear_type SW_GEAR_TYPE, --gt SW_GEAR_TYPE
Select the type of gear. Possible values: 'e', 'i',
'l'. Default: 'e'
--gear_tooth_nb SW_GEAR_TOOTH_NB, --gtn SW_GEAR_TOOTH_NB
Set the number of teeth of the first gear_profile.
--gear_module SW_GEAR_MODULE, --gm SW_GEAR_MODULE
Set the module of the gear. It influences the
gear_profile diameters.
--gear_primitive_diameter SW_GEAR_PRIMITIVE_DIAMETER, --gpd SW_GEAR_PRIMITIVE_DIAMETER
If not zero, redefine the gear module to get this
primitive diameter of the first gear_profile. Default:
0. If gearbar, it redefines the length.
--gear_addendum_dedendum_parity SW_GEAR_ADDENDUM_DEDENDUM_PARITY, --gadp SW_GEAR_ADDENDUM_DEDENDUM_PARITY
Set the addendum / dedendum parity of the first
gear_profile. Default: 50.0%
--gear_tooth_half_height SW_GEAR_TOOTH_HALF_HEIGHT, --gthh SW_GEAR_TOOTH_HALF_HEIGHT
If not zero, redefine the tooth half height of the
first gear_profile. Default: 0.0
--gear_addendum_height_pourcentage SW_GEAR_ADDENDUM_HEIGHT_POURCENTAGE, --gahp SW_GEAR_ADDENDUM_HEIGHT_POURCENTAGE
Set the addendum height of the first gear_profile in
pourcentage of the tooth half height. Default: 100.0%
--gear_dedendum_height_pourcentage SW_GEAR_DEDENDUM_HEIGHT_POURCENTAGE, --gdhp SW_GEAR_DEDENDUM_HEIGHT_POURCENTAGE
Set the dedendum height of the first gear_profile in
pourcentage of the tooth half height. Default: 100.0%
--gear_hollow_height_pourcentage SW_GEAR_HOLLOW_HEIGHT_POURCENTAGE, --ghhp SW_GEAR_HOLLOW_HEIGHT_POURCENTAGE
Set the hollow height of the first gear_profile in
pourcentage of the tooth half height. The hollow is a
136 Chapter 16. Gear Profile Function
Cnc25D Documentation, Release 0.1.11
clear space for the top of the teeth of the other
gearwheel. Default: 25.0%
--gear_router_bit_radius SW_GEAR_ROUTER_BIT_RADIUS, --grr SW_GEAR_ROUTER_BIT_RADIUS
Set the router_bit radius used to create the gear
hollow of the first gear_profile. Default: 0.1
--gear_base_diameter SW_GEAR_BASE_DIAMETER, --gbd SW_GEAR_BASE_DIAMETER
If not zero, redefine the base diameter of the first
gear involute. Default: 0
--gear_force_angle SW_GEAR_FORCE_ANGLE, --gfa SW_GEAR_FORCE_ANGLE
If not zero, redefine the gear_base_diameter to get
this force angle at the gear contact. Default: 0.0
--gear_tooth_resolution SW_GEAR_TOOTH_RESOLUTION, --gtr SW_GEAR_TOOTH_RESOLUTION
It sets the number of segments of the gear involute.
Default: 2
--gear_skin_thickness SW_GEAR_SKIN_THICKNESS, --gst SW_GEAR_SKIN_THICKNESS
Add or remove radial thickness on the gear involute.
Default: 0.0
--gear_base_diameter_n SW_GEAR_BASE_DIAMETER_N, --gbdn SW_GEAR_BASE_DIAMETER_N
If not zero, redefine the base diameter of the first
gear negative involute. Default: 0
--gear_force_angle_n SW_GEAR_FORCE_ANGLE_N, --gfan SW_GEAR_FORCE_ANGLE_N
If not zero, redefine the negative_gear_base_diameter
to get this force angle at the gear contact. Default:
0.0
--gear_tooth_resolution_n SW_GEAR_TOOTH_RESOLUTION_N, --gtrn SW_GEAR_TOOTH_RESOLUTION_N
If not zero, it sets the number of segments of the
gear negative involute. Default: 0
--gear_skin_thickness_n SW_GEAR_SKIN_THICKNESS_N, --gstn SW_GEAR_SKIN_THICKNESS_N
If not zero, add or remove radial thickness on the
gear negative involute. Default: 0.0
--second_gear_type SW_SECOND_GEAR_TYPE, --sgt SW_SECOND_GEAR_TYPE
Select the type of gear. Possible values: 'e', 'i',
'l'. Default: 'e'
--second_gear_tooth_nb SW_SECOND_GEAR_TOOTH_NB, --sgtn SW_SECOND_GEAR_TOOTH_NB
Set the number of teeth of the second gear_profile.
--second_gear_primitive_diameter SW_SECOND_GEAR_PRIMITIVE_DIAMETER, --sgpd SW_SECOND_GEAR_PRIMITIVE_DIAMETER
If not zero, redefine the gear module to get this
primitive diameter of the second gear_profile.
Default: 0.0. If gearbar, it redefines the length.
--second_gear_addendum_dedendum_parity SW_SECOND_GEAR_ADDENDUM_DEDENDUM_PARITY, --sgadp SW_SECOND_GEAR_ADDENDUM_DEDENDUM_PARITY
Overwrite the addendum / dedendum parity of the second
gear_profile if different from 0.0. Default: 0.0%
--second_gear_tooth_half_height SW_SECOND_GEAR_TOOTH_HALF_HEIGHT, --sgthh SW_SECOND_GEAR_TOOTH_HALF_HEIGHT
If not zero, redefine the tooth half height of the
second gear_profile. Default: 0.0
--second_gear_addendum_height_pourcentage SW_SECOND_GEAR_ADDENDUM_HEIGHT_POURCENTAGE, --sgahp SW_SECOND_GEAR_ADDENDUM_HEIGHT_POURCENTAGE
Set the addendum height of the second gear_profile in
pourcentage of the tooth half height. Default: 100.0%
--second_gear_dedendum_height_pourcentage SW_SECOND_GEAR_DEDENDUM_HEIGHT_POURCENTAGE, --sgdhp SW_SECOND_GEAR_DEDENDUM_HEIGHT_POURCENTAGE
Set the dedendum height of the second gear_profile in
pourcentage of the tooth half height. Default: 100.0%
--second_gear_hollow_height_pourcentage SW_SECOND_GEAR_HOLLOW_HEIGHT_POURCENTAGE, --sghhp SW_SECOND_GEAR_HOLLOW_HEIGHT_POURCENTAGE
Set the hollow height of the second gear_profile in
pourcentage of the tooth half height. The hollow is a
clear space for the top of the teeth of the other
gearwheel. Default: 25.0%
--second_gear_router_bit_radius SW_SECOND_GEAR_ROUTER_BIT_RADIUS, --sgrr SW_SECOND_GEAR_ROUTER_BIT_RADIUS
If not zero, overwrite the router_bit radius used to
16.2. gear_profile() function arguments list 137
Cnc25D Documentation, Release 0.1.11
create the gear hollow of the second gear_profile.
Default: 0.0
--second_gear_base_diameter SW_SECOND_GEAR_BASE_DIAMETER, --sgbd SW_SECOND_GEAR_BASE_DIAMETER
If not zero, redefine the base diameter of the second
gear involute. Default: 0.0
--second_gear_tooth_resolution SW_SECOND_GEAR_TOOTH_RESOLUTION, --sgtr SW_SECOND_GEAR_TOOTH_RESOLUTION
If not zero, it sets the number of segments of the
second gear involute. Default: 0
--second_gear_skin_thickness SW_SECOND_GEAR_SKIN_THICKNESS, --sgst SW_SECOND_GEAR_SKIN_THICKNESS
Add or remove radial thickness on the gear involute.
Default: 0.0
--second_gear_base_diameter_n SW_SECOND_GEAR_BASE_DIAMETER_N, --sgbdn SW_SECOND_GEAR_BASE_DIAMETER_N
If not zero, redefine the base diameter of the second
gear negative involute. Default: 0.0
--second_gear_tooth_resolution_n SW_SECOND_GEAR_TOOTH_RESOLUTION_N, --sgtrn SW_SECOND_GEAR_TOOTH_RESOLUTION_N
If not zero, it sets the number of segments of the
second gear negative involute. Default: 0
--second_gear_skin_thickness_n SW_SECOND_GEAR_SKIN_THICKNESS_N, --sgstn SW_SECOND_GEAR_SKIN_THICKNESS_N
If not zero, add or remove radial thickness on the
gear negative involute. Default: 0.0
--gearbar_slope SW_GEARBAR_SLOPE, --gbs SW_GEARBAR_SLOPE
if not zero, set the tooth slope angle for the
gearbar. Default 0.0
--gearbar_slope_n SW_GEARBAR_SLOPE_N, --gbsn SW_GEARBAR_SLOPE_N
if not zero, set the tooth negative slope angle for
the gearbar. Default 0.0
--center_position_x SW_CENTER_POSITION_X, --cpx SW_CENTER_POSITION_X
Set the x-position of the first gear_profile center.
Default: 0.0
--center_position_y SW_CENTER_POSITION_Y, --cpy SW_CENTER_POSITION_Y
Set the y-position of the first gear_profile center.
Default: 0.0
--gear_initial_angle SW_GEAR_INITIAL_ANGLE, --gia SW_GEAR_INITIAL_ANGLE
Set the gear reference angle (in Radian). Default: 0.0
--second_gear_position_angle SW_SECOND_GEAR_POSITION_ANGLE, --sgpa SW_SECOND_GEAR_POSITION_ANGLE
Angle in Radian that sets the postion on the second
gear_profile. Default: 0.0
--second_gear_additional_axis_length SW_SECOND_GEAR_ADDITIONAL_AXIS_LENGTH, --sgaal SW_SECOND_GEAR_ADDITIONAL_AXIS_LENGTH
Set an additional value for the inter-axis length
between the first and the second gear_profiles.
Default: 0.0
--cut_portion SW_CUT_PORTION SW_CUT_PORTION SW_CUT_PORTION, --cp SW_CUT_PORTION SW_CUT_PORTION SW_CUT_PORTION
(N, first_end, last_end) If N>1, cut a portion of N
tooth ofthe gear_profile. first_end and last_end
defines in details where the profile stop (0: slope-
top, 1: top-middle, 2: slope-bottom, 3: hollow-
middle). Default: (0,0,0)
--gear_profile_height SW_GEAR_PROFILE_HEIGHT, --gwh SW_GEAR_PROFILE_HEIGHT
Set the height of the linear extrusion of the first
gear_profile. Default: 1.0
--simulation_enable, --se
It display a Tk window where you can observe the gear
running. Check with your eyes if the geometry is
working.
--output_file_basename SW_OUTPUT_FILE_BASENAME, --ofb SW_OUTPUT_FILE_BASENAME
If not the empty_string (the default value), it
outputs the (first) gear in file(s) depending on your
argument file_extension: .dxf uses mozman dxfwrite,
138 Chapter 16. Gear Profile Function
Cnc25D Documentation, Release 0.1.11
.svg uses mozman svgwrite, no-extension uses FreeCAD
and you get .brep and .dxf
--run_self_test, --rst
Generate several corner cases of parameter sets and
display the Tk window where you should check the gear
running.
16.3 From gear_profile() arguments to high-level parameters
16.3.1 Gear type
Gear type possible values:
- e : external (a.k.a. gearwheel)
- i : internal (a.k.a. gearring)
- l : linear (a.k.a. gearbar)
16.3.2 Gear tooth number (N)
N > 2
16.3.3 Gear module (m)
Set after those priorities:
1. gear-module parameter
2. primitive diameter parameter (m=pd/N)
3. second primitive diameter parameter (m=pd2/N2)
4. the default value (m=1)
16.3.4 Gear base diameter (bd)
Set after those priorities:
1. gear base diameter parameter
2. second gear base diameter parameter (bd=bd2 *N1/N2)
3. gearbar slope angle (bd=pd *cos(sa))
4. force angle parameter (bd=pd *cos(fa))
5. the default value (bd=[dedendum diameter of the smallest gear])
When two gears are specified (by setting second_gear_tooth_nb), and the gear base diameter is not constrainted, the
dedendum diameter of the smallest gear is used to calculate the gear base diameter.
16.3.5 Gearbar slope angle (sa)
It is only applicable with a gearbar. Because gearbar-gearbar system doesn’t exist, the first and the second gear share
the parameters gearbar_slope andgearbar_slope_n .
Set after those priorities:
16.3. From gear_profile() arguments to high-level parameters 139
Cnc25D Documentation, Release 0.1.11
1. gearbar_slope parameter
2. force angle parameter (sa=fa)
3. second gear base diameter parameter (sa=acos(bd/pd))
The Gearbar slope has no default value and must be constraint by one of those three possibilities.
16.4 Complement on gear high-level parameters
16.4.1 Gearwheel angle position
140 Chapter 16. Gear Profile Function
Cnc25D Documentation, Release 0.1.11
16.4.2 Simluation cases
16.4. Complement on gear high-level parameters 141
Cnc25D Documentation, Release 0.1.11
142 Chapter 16. Gear Profile Function
CHAPTER 17
Gear Guidelines
17.1 Strength and deformation
17.2 Gear module
Thegear module defines the size of a gear tooth. Two gearwheels working together must have the same gear module :
circular_pitch = Pi *gear_module
Per default, the tooth height is defined with the gear module :
addendum_height = gear_module
dedendum_height = gear_module
tooth_height = 2 *gear_module
A small gear module generates less friction and then provides a better energy transmission efficiency. A large gear
module supports higher efforts:
143
Cnc25D Documentation, Release 0.1.11
Module sizing formula in the literaure:
m>2.34*sqrt(T/(k *Rpe))
with:
T = tangential effort on the tooth = F *cos(a)
torque = C = d *F
d = R*cos(a) (R = primitive radius = Z *m/2)
T = F*cos(a) = C/d *cos(a) = C/R
k = tooth width coefficient (usually k=8 or 10)
tooth width = b = k *m
Rpe = Re/s
Re = Yield = elasticity limit
s = security coefficient
144 Chapter 17. Gear Guidelines
CHAPTER 18
Gear Profile Theory
18.1 Transmission per adhesion
(O,i,j) orthonormal reference frame
wheel_1 rotation speed: u (radian/s)
wheel_2 rotation speed: v (radian/s)
speed of M, point of wheel_1:
V(M) = u *R1*j
speed of N, point of wheel_2:
V(N) = v *R2*j
Because of the adhesion of the wheel_1 and wheel_2 in M:
145
Cnc25D Documentation, Release 0.1.11
V(M).j = V(N).j
u*R1 = v*R2
v = u*R1/R2
18.1.1 Issue
The maximal torque transmission is limited by the adhesion capacity.
18.1.2 Idea
Create hollows and bums around the wheel to get a contact point force transmission.
18.2 Transmission with teeth
18.2.1 One wheel description
angular_pitch = 2 *pi/tooth_nb
circular_pitch = angular_pitch *primitive radius
addendum_radius = primitive_radius + addendum_height
dedendum_radius = primitive_radius + dedendum_height
tooth_height = addendum_height + dedendum_height
146 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
18.2.2 Conditions for working gear
circular_pitch_1 = circular_pitch_2
addendum_height_1 < dedendum_height_2
addendum_height_2 < dedendum_height_1
transmission ratio = primitive_radius_1 / primitive_radius_2 = tooth_nb_1 / tooth_nb_2
Problematic: How to design the tooth-profile?
18.3 Tooth profile
Cartesian equation:
Mx(a) = R *cos(a)+a *R*cos(a-pi/2)
My(a) = R *sin(a)+a *R*sin(a-pi/2)
Trigonometry formula remind:
cos(-x) = cos(x)
sin(-x) = -sin(x)
cos(pi/2-x) = sin(x)
sin(pi/2-x) = cos(x)
cos(a-pi/2)=cos(pi/2-a)=sin(a)
sin(a-pi/2)=-sin(pi/2-a)=-cos(a)
Tangent vector:
Mx'(a) = -R *sin(a)+R *cos(a-pi/2)-a *R*sin(a-pi/2) = -a *R*sin(a-pi/2) = a *R*cos(a)
My'(a) = R *cos(a)+R *sin(a-pi/2)+a *R*cos(a-pi/2) = a *R*cos(a-pi/2) = a *R*sin(a)
18.3. Tooth profile 147
Cnc25D Documentation, Release 0.1.11
148 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
18.3. Tooth profile 149
Cnc25D Documentation, Release 0.1.11
150 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
u: rotation speed of the wheel
v: linear speed of tha bar
u(t) = d/dt(a(t))
OM = sqrt(R² + (a *R)²) = R *sqrt(1+a²)
S = OM*u
Sn = S*cos(b)
St = S*sin(b)
Sn = u*R*sqrt(1+a²) *cos(b)
relation between a(t) and b(t)?
tan(b) = (a *R)/R = a
Sn = u*R*sqrt(1+tan²(b)) *cos(b)
Trigonometry formula remind:
1+tan²(x) = (cos²(x)+sin²(x))/cos²(x) = 1/cos²(x)
So,:
v = Sn = u *R
v does not depend on the angle a!
St = u*R*sqrt(1+a²) *sin(b) = u *R*tan(b) = u *R*a
18.3. Tooth profile 151
Cnc25D Documentation, Release 0.1.11
u: rotation speed of the wheel
v: linear speed of tha bar
u(t) = d/dt(a(t))
OM = sqrt(R² + (a *R)²) = R *sqrt(1+a²)
S = OM*u
Sn = S*cos(b)
St = S*sin(b)
v = Sn = u *R*sqrt(1+a²) *cos(b)
= u*R*sqrt(1+tan²(b)) *cos(b) = u *R
v does not depend on the angle a!
St = u*R*sqrt(1+a²) *sin(b) = u *R*tan(b) = u *R*a
152 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
v = u1*R1 = u2*R2
So, u2 = u1 *R1/R2
18.3. Tooth profile 153
Cnc25D Documentation, Release 0.1.11
Sn1 = Sn2 because of the contact
154 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
Friction between the two wheels:
Sf = St2 - St1 = u2 *R2*a2 - u1*R1*a1
= u1*R1*(a2-a1)
But,
a1 = k1-u1 *t
a2 = k2+u2 *t
Sf = u1*R1*(k1-k2+(u1+u2) *t)
18.3. Tooth profile 155
Cnc25D Documentation, Release 0.1.11
18.4 Gear profile construction
156 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
18.5 Gear rules
• The base diameter of the two directions can be different
•The top-land and bottom-land are not critical part of the profile The top-land can be a straight line. The
bottom-land is usually a hollow to help the manufacturing.
• The rotation ratio implies by the involutes-of-circles is:
base_radius_1 / base_radius_2
The rotation ratio implies by the teeth is:
tooth_nb_1 / tooth_nb_2
In order to get a continuous transmission without cough, we must ensure that:
base_radius_1 / base_radius_2 = tooth_nb_1 / tooth_nb_2
If you use two base circles for the positive rotation and the negative rotation, then:
base_radius_positive_1 / base_radius_positive_2 = tooth_nb_1 / tooth_nb_2
base_radius_negative_1 / base_radius_negative_2 = tooth_nb_1 / tooth_nb_2
• The position of the positive involute of circle compare to the negative involute of circle is arbitrary and it is
usually defined by the addendum-dedendum-ration on the primitive circle. Just make sure the top-land and
bottom-land still exist (positive length). The addendum-dedendum-ration of the second wheel must be the
complementary.
18.5. Gear rules 157
Cnc25D Documentation, Release 0.1.11
Do not mix-up the primitive circle and the base circle . The primitive circle helps defining the addendum anddedendum
circles. The base circle defines the involutes of circle .We have the relation:
base_radius < primitive_radius
158 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
18.6 Torque transmission
F = T1/R1 = T2/R2
T2 = T1*R2/R1
The transmitted torque T2 does not depend on the angle a!
18.6. Torque transmission 159
Cnc25D Documentation, Release 0.1.11
18.7 Gearwheel position
160 Chapter 18. Gear Profile Theory
Cnc25D Documentation, Release 0.1.11
The rotation ration depends only on the two base circle diameters. It does not depend on the inter-axis length. The
inter-axis length can be set arbitrary within a reasonable range (addendum and dedendum height constraints).
18.7. Gearwheel position 161
Cnc25D Documentation, Release 0.1.11
162 Chapter 18. Gear Profile Theory
CHAPTER 19
Gear Profile Details
19.1 Involute of circle
163
Cnc25D Documentation, Release 0.1.11
164 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.1. Involute of circle 165
Cnc25D Documentation, Release 0.1.11
166 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.2 Gear outline
19.2.1 Gearwheel
19.2. Gear outline 167
Cnc25D Documentation, Release 0.1.11
168 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.2. Gear outline 169
Cnc25D Documentation, Release 0.1.11
19.2.2 Gearring
170 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.2.3 Gearbar
19.2. Gear outline 171
Cnc25D Documentation, Release 0.1.11
172 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.2.4 Gear hollow
19.2. Gear outline 173
Cnc25D Documentation, Release 0.1.11
174 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.3 Gear position
19.3.1 Gearwheel
19.3. Gear position 175
Cnc25D Documentation, Release 0.1.11
19.3.2 Gearbar
176 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.3.3 Position with additional inter-axis length
19.3. Gear position 177
Cnc25D Documentation, Release 0.1.11
178 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.3. Gear position 179
Cnc25D Documentation, Release 0.1.11
180 Chapter 19. Gear Profile Details
Cnc25D Documentation, Release 0.1.11
19.3. Gear position 181
Cnc25D Documentation, Release 0.1.11
182 Chapter 19. Gear Profile Details
183
Cnc25D Documentation, Release 0.1.11
CHAPTER 20
Gear Profile Implementation
20.1 Internal data-flow
184 Chapter 20. Gear Profile Implementation
CHAPTER 21
Gearwheel Design
Ready-to-use parametric gearwheel design (a.k.a. spur).
185
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible gearwheel designs that can be gearwheel() , run:
> python gearwheel.py --run_self_test
21.1 Gearwheel Parameter List
The parameter relative to the gear-profile are directly inherit from the Gear Profile Function.
186 Chapter 21. Gearwheel Design
Cnc25D Documentation, Release 0.1.11
21.1. Gearwheel Parameter List 187
Cnc25D Documentation, Release 0.1.11
21.2 Gearwheel Parameter Dependency
21.2.1 router_bit_radius
Four router_bit radius are defined: gear_router_bit_radius ,wheel_hollow_router_bit_radius ,axle_router_bit_radius
and cnc_router_bit_radius . Each set the router_bit radius for different areas except cnc_router_bit_radius that
set the mimnimum value for the three other router_bit radius. If an other router_bit radius is smaller than
cnc_router_bit_radius , it is set to cnc_router_bit_radius . So, we have the relations:
cnc_router_bit_radius < gear_router_bit_radius
cnc_router_bit_radius < wheel_hollow_router_bit_radius
cnc_router_bit_radius < axle_router_bit_radius
21.2.2 axle_type
Three possible shapes of axle are possible: none ,circle orrectangle .none means there is no axle ( axle_x_width and
axle_y_width are ignored). For circle , the parameter axle_x_width is used to set the circle diameter ( axle_y_width is
ignored). axle_x_width andaxle_y_width must be bigger than twice axle_router_bit_radius :
2*axle_router_bit_radius < axle_x_width
2*axle_router_bit_radius < axle_y_width
188 Chapter 21. Gearwheel Design
Cnc25D Documentation, Release 0.1.11
21.2.3 wheel_hollow_leg_number
wheel_hollow_leg_number sets the number of legs (equal the number of wheel_hollows). If you set
zero, no wheel_hollow are created and the other parameters related to the wheel_hollow are ignored.
wheel_hollow_internal_diameter must be bigger than the axle. wheel_hollow_external_diameter must be smaller
than the gear_hollow_diameter (which is not a parameter but derivated from other gear parameter):
axle_x_width < wheel_hollow_internal_diameter
sqrt(axle_x_width²+axle_y_width²) < wheel_hollow_internal_diameter
wheel_hollow_internal_diameter + 4 *wheel_hollow_router_bit_radius < wheel_hollow_external_diameter
wheel_hollow_external_diameter < gear_hollow_diameter
21.2.4 gear_tooth_nb
gear_tooth_nb sets the number of teeth of the gear_profile. If gear_tooth_nb is set to zero, the gear_profile is replaced
by a simple circle of diameter gear_primitive_radius .
21.2.5 Alignment angles
The rectangle axle is always fixed to the XY-axis. The angle between the first wheel_hollow leg (middle of it) and the
X-axis is set with wheel_hollow_leg_angle . The angle between the first gear_profile tooth (middle of the addendum)
and the X-axis is set with gear_initial_angle .
21.2.6 crenel_mark_nb
crenel_mark_nb lets you modify the first (or the several first) crenel to help you recognizing the first tooth. If the
crenel_type is set to rectangle , the right-angle of the first crenels are rounded. If the crenel_type is set to circle , the
first crenels have a egg-form. If you don’t want to mark the first crenel, set crenel_mark_nb tozero. This feature is
useful when you work with small gearwheel and you want to align them easily.
21.2.7 crenel_tooth_align
crenel_tooth_align is an alternative to the parameters crenel_number andcrenel_angle . Ifcrenel_tooth_align is set to
a positive integer N, crenels are generated just under the gear-teeth, every N teeth. This feature is useful when you
have a small space between the gear-teeth and the axle. In this case, material must be optimized by aligning crenel
and teeth to avoid weak points (a.k.a. bottle-neck). To use crenel_tooth_align , the parameters crenel_number and
crenel_angle must be set to zero.
21.2. Gearwheel Parameter Dependency 189
Cnc25D Documentation, Release 0.1.11
190 Chapter 21. Gearwheel Design
CHAPTER 22
Gearring Design
Ready-to-use parametric gearring design (a.k.a. annulus).
191
Cnc25D Documentation, Release 0.1.11
192 Chapter 22. Gearring Design
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible gearring designs that can be gearring() , run:
> python gearring.py --run_self_test
22.1 Gearring Parameter List
The parameter relative to the gear-profile are directly inherit from the Gear Profile Function.
22.1. Gearring Parameter List 193
Cnc25D Documentation, Release 0.1.11
194 Chapter 22. Gearring Design
Cnc25D Documentation, Release 0.1.11
22.1. Gearring Parameter List 195
Cnc25D Documentation, Release 0.1.11
196 Chapter 22. Gearring Design
Cnc25D Documentation, Release 0.1.11
22.2 Gearring Parameter Dependency
22.2.1 router_bit_radius
Four router_bit radius are defined: gear_router_bit_radius , holder_crenel_router_bit_radius ,
holder_smoothing_radius and cnc_router_bit_radius . Each set the router_bit radius for different areas except
cnc_router_bit_radius that set the minimum value for the three other router_bit radius. If an other router_bit radius is
smaller than cnc_router_bit_radius , it is set to cnc_router_bit_radius . So, we have the relations:
cnc_router_bit_radius < gear_router_bit_radius
cnc_router_bit_radius < holder_crenel_router_bit_radius
cnc_router_bit_radius < holder_smoothing_radius
If you leave holder_smoothing_radius to 0.0, it will be changed automatically to the biggest possible value.
22.2.2 holder_hole_diameter
holder_hole_diameter sets the diameter of the holder-holes. If holder_hole_diameter is set to 0.0, no holder-hole are
created.
22.2.3 holder_crenel_number
holder_crenel_number sets the number of holder-crenels (equal to the number of holder-hole). If
holder_crenel_number is set to zero, no holder-crenel is created and the outline of the gearring is a simple circle.
22.2.4 holder_crenel_width
holder_crenel_width must be bigger than the router_bit diameter:
holder_crenel_width > 2 *holder_crenel_router_bit_radius
Ifholder_crenel_width is big enough, the crenel bottom shape is changed to get alternative enlarged corners.
22.2.5 gear_tooth_nb
gear_tooth_nb sets the number of teeth of the gear_profile. If gear_tooth_nb is set to zero, the gear_profile is replaced
by a simple circle of diameter gear_primitive_radius .
22.2.6 Alignment angles
gear_initial_angle sets the angle between the X-axis and the middle of the addendum of the first tooth.
holder_position_angle sets the angle between the X-axis and the middle of the first holder-crenel. Use
gear_initial_angle orholder_position_angle or both to ajust the offset angle between the gear-profile anf the gearring-
holder.
22.2.7 holder_hole_mark_nb
holder_hole_mark_nb lets you modify the first (or the several first) crenel to help you recognizing the first tooth. The
first crenels have a egg-form instead of the circle-form. If you don’t want to mark the first crenel, set crenel_mark_nb
tozero. This feature is useful when you need pile up gearring and find easily the first tooth to align them.
22.2. Gearring Parameter Dependency 197
Cnc25D Documentation, Release 0.1.11
22.2.8 holder_double_hole
In addition to the holder_hole , you can generate the holder_double_hole defined by the parameters
holder_double_hole_diameter ,holder_double_hole_length and holder_double_holde_position . The distance
between the two double_holes is set by holder_double_hole_length . The radius position is set by
holder_double_holde_position relative to the holder_hole_position_radius . The holder_double_holes are useful when
you use the crenel-hole with thin steel-rod for alignment and Z-shearing resistance and you want to increase the
stability. At the same time, you can use the holder_holes to put threaded rods.
198 Chapter 22. Gearring Design
CHAPTER 23
Gearbar Design
Ready-to-use parametric gearbar design (a.k.a. rack).
199
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible gearbar designs that can be gearbar() , run:
> python gearbar.py --run_self_test
23.1 Gearbar Parameter List
The parameter relative to the gear-profile are directly inherit from the Gear Profile Function.
200 Chapter 23. Gearbar Design
Cnc25D Documentation, Release 0.1.11
23.2 Gearbar Parameter Dependency
23.2.1 gearbar_hole_diameter
gearbar_hole_diameter sets the diameter of the gearbar-holes. If gearbar_hole_diameter is set to 0.0, no gearbar-hole
are created.
23.2.2 gearbar_hole_height_position
gearbar_hole_height_position sets the vertical position of the gearbar-hole centers. gearbar_hole_height_position
must be placed between the bottom of the gearbar and the gear-profile:
gearbar_hole_radius = gearbar_hole_diameter/2
gearbar_hole_height_position > gearbar_hole_radius
gearbar_hole_height_position < minimal_gear_profile_height - gearbar_hole_radius
23.2.3 gearbar_hole_offset and gearbar_hole_increment
The abscissas of the centers of the gearbar-holes are always located at the middle of the addendum of a gear-tooth.
gearbar_hole_offset sets the number of gear-teeth between the left-side of the gearbar to the first gearbar-hole. gear-
bar_hole_increment sets the number of gear-teeth between two consecutive gearbar-holes:
gearbar_hole_increment > 0
23.2. Gearbar Parameter Dependency 201
Cnc25D Documentation, Release 0.1.11
23.2.4 gear_tooth_nb
gear_tooth_nb sets the number of teeth of the gear_profile. If gear_tooth_nb is set to zero, the gear_profile is replaced
by a simple line of length gear_primitive_radius .
23.2.5 Alignment
gear_initial_angle ,center_position_x ,center_position_y andsecond_gear_position_angle are only used for the sim-
ulation. The gearbar as a simple display, as a FreeCAD object or as a design file is always placed to get its bottom-left
corner at the (0,0) coordinates.
202 Chapter 23. Gearbar Design
CHAPTER 24
Split-gearwheel Design
Ready-to-use parametric split-gearwheel design (i.e. spur that is split for its fabrication).
203
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible split-gearwheel designs that can be split_gearwheel() , run:
> python split_gearwheel.py --run_self_test
24.1 Split-gearwheel Parameter List
The parameter relative to the gear-profile are directly inherit from the Gear Profile Function.
204 Chapter 24. Split-gearwheel Design
Cnc25D Documentation, Release 0.1.11
24.2 Split-gearwheel Parameter Dependency
24.2.1 router_bit_radius
Three router_bit radius are defined: gear_router_bit_radius ,split_router_bit_radius , and cnc_router_bit_radius . Each
set the router_bit radius for different areas except cnc_router_bit_radius that set the mimnimum value for the two other
router_bit radius. If an other router_bit radius is smaller than cnc_router_bit_radius , it is set to cnc_router_bit_radius .
So, we have the relations:
cnc_router_bit_radius < gear_router_bit_radius
cnc_router_bit_radius < split_router_bit_radius
24.2.2 split_nb
split_nb defines in how many parts the gearwheel must be split. The split_gearwheel() function generates two sets
(A and B) of split_nb parts. So you get at the end 2*split_nb parts. The set A (respectively B) makes a complete
gearwheel. The set-A-gearwheel and the set-B-gearwheel can be stick together to ensure a better stability. The low-
holes andhigh-holes ensure a good alignment between the set-A parts and set-B parts. The parameters low_hole_nb
andhigh_hole_nb define the number of holes per half-split-portion i.e. the common portion between a set-A parts and
a set-B part.
24.2. Split-gearwheel Parameter Dependency 205
Cnc25D Documentation, Release 0.1.11
24.2.3 low_split_diameter and high_split_diameter
The constraints define 5 circles: low_split_diameter ,low_hole_circle_diameter ,high_hole_circle_diameter ,
high_split_diameter andminimal_gear_profile_radius (inferred from the gear-profile). If gear_tooth_nb = 0 then
high_split_diameter =minimal_gear_profile_radius . These five circles are strictly included in each others:
low_split_diameter + low_hole_radius < low_hole_circle_diameter
low_hole_circle_diameter + low_hole_radius + high_hole_radius < high_hole_circle_diameter
high_hole_circle_diameter + high_hole_radius < high_split_diameter
high_split_diameter < minimal_gear_profile_radius
24.2.4 low_split_type
low_split_type defines the outline at the low-split-circle:
circle : the outline is an arc of circle
line : the outline is composed of two lines
24.2.5 high_split_type
high_split_type defines how to join the split radius with the gear-profile. Indeed the number of gear-teeth and the
number of split-portion are independant. In most of the case, the gear-hollow doesn’t fit exactly the split radius. The
split radius stops at the high-split circle. Then, the outline goes straight to the gear-profile. The angle at the high-split
circle is smooth with split_router_bit_radius . The possible values for high_split_type are:
'h': the outline goes to the closest gear-hollow middle
'a': the outline goes to the addendum middle if it best fits, otherwise it goes to the closest gear-hollow middle
24.2.6 gear_tooth_nb
gear_tooth_nb sets the number of teeth of the gear_profile. If gear_tooth_nb is set to zero, the gear_profile is replaced
by a simple circle of diameter gear_primitive_radius .
24.2.7 Alignment angles
gear_initial_angle sets the angle between the X-axis and the middle of the addendum of the first tooth.
split_initial_angle sets the angle between the X-axis and the first split radius. Use gear_initial_angle or
split_initial_angle or both to ajust the offset angle between the gear-profile anf the split-portion.
206 Chapter 24. Split-gearwheel Design
CHAPTER 25
Epicyclic Gearing Design
Ready-to-use parametric epicyclic-gearing design. Check also the epicyclic-gearing design variants
Low_torque_transmission Design and High_torque_transmission Design that might better fit your requirements.
Theepicyclic gearing is a system made out of several parts:
• sun-gear
• planet-gear
• annulus-gear
• planet-carrier (rear, middle and front)
207
Cnc25D Documentation, Release 0.1.11
208 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
You can generate several configuration of epicyclic gearing system :
209
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible epicyclic-gearing designs that can be epicyclic_gearing() , run:
210 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
> python epicyclic_gearing.py --run_self_test
25.1 Epicyclic Gearing Parameter List
The parameter relative to the gearring are inherit from the Gearring Design.
25.1. Epicyclic Gearing Parameter List 211
Cnc25D Documentation, Release 0.1.11
212 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
25.1. Epicyclic Gearing Parameter List 213
Cnc25D Documentation, Release 0.1.11
214 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
25.1. Epicyclic Gearing Parameter List 215
Cnc25D Documentation, Release 0.1.11
25.2 Epicyclic Gearring Parameter Dependency
25.2.1 router_bit_radius
Six router_bit radius are defined: gear_router_bit_radius , sun_crenel_router_bit_radius ,
planet_crenel_router_bit_radius , carrier_crenel_router_bit_radius , carrier_smoothing_radius and
cnc_router_bit_radius . Each set the router_bit radius for different areas except cnc_router_bit_radius that set the
minimum value for the five other router_bit radius. If an other router_bit radius is smaller than cnc_router_bit_radius ,
it is set to cnc_router_bit_radius . So, we have the relations:
cnc_router_bit_radius < gear_router_bit_radius
cnc_router_bit_radius < sun_crenel_router_bit_radius
cnc_router_bit_radius < planet_crenel_router_bit_radius
cnc_router_bit_radius < carrier_crenel_router_bit_radius
cnc_router_bit_radius < carrier_smoothing_radius
If you leave carrier_smoothing_radius to 0.0, it will be changed automatically to a default larger value.
216 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
25.2.2 sun_gear_tooth_nb and planet_gear_tooth_nb
sun_gear_tooth_nb andplanet_gear_tooth_nb set the number of teeth of the sun-gear and planet-gears. The number
of teeth of the annulus-gear is set to:
annulus_gear_tooth_nb = sun_gear_tooth_nb + 2 *planet_gear_tooth_nb
To get a working epicyclic-gearing, the sum of sun_gear_tooth_nb and annulus_gear_tooth_nb must be divisible by
the number of planet-gears:
(annulus_gear_tooth_nb + sun_gear_tooth_nb) % planet_nb = 0
equivalent to:
(2*(sun_gear_tooth_nb + planet_gear_tooth_nb)) % planet_nb = 0
The transmission ration is equal to:
sun_gear_tooth_nb/(sun_gear_tooth_nb + annulus_gear_tooth_nb)
25.2.3 planet_nb
planet_nb sets the number of planet-gears. If planet_nb is set to 0, the maximal number of planet-gears is chosen.
25.2.4 carrier_peripheral_disable
Ifcarrier_peripheral_disable isTrue, no rear-planet-carrier and no middle-planet-carrier are generated. The front-
planet-carrier has also an alternative design.
25.2.5 carrier_hollow_disable
Ifcarrier_hollow_disable isTrue, hollows are created in the front-planet-carrier. This remove some material to get a
lighter system. This option is available only when carrier_peripheral_disable isFalse .
25.2.6 carrier_crenel_height
carrier_crenel_height sets the height of the carrier-crenels. If carrier_crenel_height is set to 0, the carrier-crenel are
not created. The number of carrier-crenels is 2*planet_nb.
25.2.7 planet_axle_diameter and carrier_leg_hole_diameter
planet_axle_diameter and carrier_leg_hole_diameter are both related to the diameters of the planet-gear axle.
planet_axle_diameter sets the diameter of the axle of the planet-gears. carrier_leg_hole_diameter sets the diame-
ter of the corresponding coaxial holes in the rear and front planet-carrier. Using two different values for these two
parameters can be useful when you want to use a ball bearing system.
25.2.8 sun axle and carrier axle design
The sun axle design is defined with several parameters such as sun_axle_diameter ,sun_crenel_diameter ,
sun_crenel_nb ,sun_crenel_width ,sun_crenel_height andsun_crenel_router_bit_radius . The design of the axle of
the plant-carrier is copied from the sun axle design. So there is no parameters directly related to the planet-carrier
axle design. Notice that in case of cascade epicyclic gearing, the planet-carrier of a stage intends to be jammed to the
sun-gear of the next stage.
25.2. Epicyclic Gearring Parameter Dependency 217
Cnc25D Documentation, Release 0.1.11
25.2.9 carrier_double_hole_length
The crenel-hole can is replaced by a double-crenel-hole when carrier_double_hole_length is set to a float bigger than
zero. In this case, two holes are created with a distance of carrier_double_hole_length . Double-hole are useful to
increase the stability of the planet-carrier.
25.2.10 top_lid parameters
Those parameters are inherit from Axle Lid Design
25.2.11 input and output gearwheels
Theepicyclic-gearing design can generate the input and the output gearwheels. It is recommended to re-generate those
gearwheels with the gearwheel.py script to get access to the complete Gearwheel Design parameter list.
25.3 Epicyclic Gearing Recommendations
25.3.1 For laser-cutter
The laser-cutter remove usually more material than the ideal line. This is because of the lase beam width. To get a well
adjusted gear system without too much play, we need to compensate this excess of removed material. The parameter
gear_skin_thickness lets you move the gear-profile-outline in order to compensate the laser beam width. Because the
laser remove too much material, you should set gear_skin_thickness to a positive values (e.g: 0.75 mm).
If you set a quiet large value to gear_skin_thickness , it may happens that the gear-ring (a.k.a. annulus) can not be
generated any more because its bottom-land is too small or even negative. In this case, there is a small workaround:
modify slightly the lowest part of the dedendum of the gear-ring to make this gear-hollow feasible by using the param-
etergearring_dedendum_to_hollow_pourcentage . For example, if gearring_dedendum_to_hollow_pourcentage is set
to 10, 10% of the gear-ring dedendum is changed into the gear-hollow.
gear_skin_thickness does not compensate the height of the gear-teeth. If you think the laser-cutter make the gear-teeth
too small, you can increase the value of the parameter gear_addendum_height_pourcentage . For example, if you set
gear_addendum_height_pourcentage to 110, the theoretical (before laser-cutting) gear-tooth-addendum height is set
to 1.1*gear_module.
25.3.2 For 3D printing
Usually 3D printed parts are a bit larger than the CAD design. This is because of the extruded wire width. This extra
thickness can be compensated with a negative value sets to the parameter gear_skin_thickness .
If you set a too large negative value to gear_skin_thickness , the top the gear-tooth might not be designable anymore
because the top-land will be negative. In this case, you can reduce the height of the gear-tooth addendum with the
parameter gear_addendum_height_pourcentage . For example, if you set gear_addendum_height_pourcentage to 90,
the theoretical (without the extra extruded wire width) gear-tooth-addendum height is set to 0.9*gear_module.
25.3.3 For CNC milling
With CNC, the biggest challenge is the size to the router-bit. cnc_router_bit_radius must be equal or bigger than the
effective used router-bit radius. If gear_router_bit_radius is smaller than cnc_router_bit_radius , it is automatically
sets to the value of cnc_router_bit_radius .
218 Chapter 25. Epicyclic Gearing Design
Cnc25D Documentation, Release 0.1.11
Ifgear_router_bit_radius is too large, it may happens that the gear-ring can not be generated anymore because the
gear_router_bit_radius is too large compare to the gear-hollow width. In this case, there is a small workaround: modify
slightly the lowest part of the dedendum of the gear-ring to make this gear-hollow feasible by using the parameter
gearring_dedendum_to_hollow_pourcentage . For example, if gearring_dedendum_to_hollow_pourcentage is set to
10, 10% of the gear-ring dedendum is changed into the gear-hollow.
25.3. Epicyclic Gearing Recommendations 219
Cnc25D Documentation, Release 0.1.11
220 Chapter 25. Epicyclic Gearing Design
CHAPTER 26
Epicyclic Gearing Details
221
Cnc25D Documentation, Release 0.1.11
222 Chapter 26. Epicyclic Gearing Details
Cnc25D Documentation, Release 0.1.11
223
Cnc25D Documentation, Release 0.1.11
224 Chapter 26. Epicyclic Gearing Details
CHAPTER 27
Axle Lid Design
Ready-to-use parametric axle_lid design kit. The axle_lid is a an assembly of three parts:
• annulus-holder
• middle-axle-lid
• top_axle-lid
225
Cnc25D Documentation, Release 0.1.11
226 Chapter 27. Axle Lid Design
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible axle_lid designs that can be axle_lid() , run:
> python axle_lid.py --run_self_test
27.1 Axle-lid Parameter List
The parameter relative to the external outline are inherit from the Gearring Design.
27.1. Axle-lid Parameter List 227
Cnc25D Documentation, Release 0.1.11
228 Chapter 27. Axle Lid Design
Cnc25D Documentation, Release 0.1.11
27.1. Axle-lid Parameter List 229
Cnc25D Documentation, Release 0.1.11
230 Chapter 27. Axle Lid Design
Cnc25D Documentation, Release 0.1.11
27.2 Axle-lid Parameter Dependency
27.2.1 Diameters
The following relations between diameters (or radius) must be respected:
cnc_router_bit_radius < axle_hole_diameter/2
axle_hole_diameter < central_diameter
central_diameter < clearance_diameter
clearance_diameter < holder_diameter
27.2.2 Generated files
For a same set of parameters, you may need several flavour of the design such as a plate with a hole and the same plate
without this hole. Instead of adding input parameters to select if the plate must have a hole or not, the both variants
are generated. You just need to pick up the file you need.
27.2. Axle-lid Parameter Dependency 231
Cnc25D Documentation, Release 0.1.11
232 Chapter 27. Axle Lid Design
CHAPTER 28
Axle_lid Details
233
Cnc25D Documentation, Release 0.1.11
234 Chapter 28. Axle_lid Details
Cnc25D Documentation, Release 0.1.11
235
Cnc25D Documentation, Release 0.1.11
236 Chapter 28. Axle_lid Details
CHAPTER 29
Motor Lid Design
Ready-to-use parametric motor_lid assembly. This assembly aims at holding the gear system between an electric
motor and the epicyclic-gearing. The motor_lid is an assembly of several parts:
• holder-A (a.k.a. annulus-holder)
• holder-B (a.k.a. motor-holder or axle-holder)
• holder-C
237
Cnc25D Documentation, Release 0.1.11
238 Chapter 29. Motor Lid Design
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible motor_lid designs that can be motor_lid() , run:
239
Cnc25D Documentation, Release 0.1.11
> python mostor_lid.py --run_self_test
29.1 Motor-lid Parameter List
The parameter relative to the external outline are inherit from the Gearring Design and Axle Lid Design.
240 Chapter 29. Motor Lid Design
Cnc25D Documentation, Release 0.1.11
29.1. Motor-lid Parameter List 241
Cnc25D Documentation, Release 0.1.11
242 Chapter 29. Motor Lid Design
Cnc25D Documentation, Release 0.1.11
29.1. Motor-lid Parameter List 243
Cnc25D Documentation, Release 0.1.11
244 Chapter 29. Motor Lid Design
CHAPTER 30
Bell Design
Ready-to-use parametric belldesign. It is the extremity piece of a gimbal assembly. The bellpiece is composed of
several flat parts fixed together.
245
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible belldesigns that can be bell() , run:
> python bell.py --run_self_test
30.1 Bell Parts and Geometry
Thebellis composed out of the following flat parts:
• bell_face x2
• bell_side x2
• bell_base x1
• bell_internal_buttress x8
• bell_external_buttress x8 (alternative: bell_external_buttress_face x4 and bell_external_buttress_side x4)
246 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.1. Bell Parts and Geometry 247
Cnc25D Documentation, Release 0.1.11
248 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.1. Bell Parts and Geometry 249
Cnc25D Documentation, Release 0.1.11
250 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.2 Bell Parameter List
30.2. Bell Parameter List 251
Cnc25D Documentation, Release 0.1.11
252 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.2. Bell Parameter List 253
Cnc25D Documentation, Release 0.1.11
254 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.2. Bell Parameter List 255
Cnc25D Documentation, Release 0.1.11
256 Chapter 30. Bell Design
Cnc25D Documentation, Release 0.1.11
30.3 Bell Parameter Dependency
30.3.1 router_bit_radius
The two parameters leg_smooth_radius andcnc_router_bit_radius are related to the router_bit_radius . The parameter
cnc_router_bit_radius guarantees the smallest possible router_bit_radius value. So, we have the relations:
30.3. Bell Parameter Dependency 257
Cnc25D Documentation, Release 0.1.11
cnc_router_bit_radius < leg_smooth_radius
258 Chapter 30. Bell Design
CHAPTER 31
Bell Details
Construction details of the belldesign.
259
Cnc25D Documentation, Release 0.1.11
260 Chapter 31. Bell Details
Cnc25D Documentation, Release 0.1.11
261
Cnc25D Documentation, Release 0.1.11
262 Chapter 31. Bell Details
CHAPTER 32
Bagel Design
Ready-to-use parametric bagel design. It is the axle-guidance for the bellpiece. The bagel is fixed to the bellbut is
mounted after the axle has been set in positon.
263
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible bagel designs that can be bagel() , run:
> python bagel.py --run_self_test
32.1 Bagel Parts and Parameters
Thebagel is composed out of the following flat parts:
• external_bagel
• middle_bagel
• internal_bagel
264 Chapter 32. Bagel Design
Cnc25D Documentation, Release 0.1.11
32.2 Bagel Parameter Dependency
32.2.1 axle_internal_diameter
Thebelldesign and the bagel design have both the axle_internal_diameter parameter. With ideal conditions, these two
parameters get the same value. But you might want to but slightly different values to adjust the fit of the middle_bagel
into the bell axle internal hole .
32.2. Bagel Parameter Dependency 265
Cnc25D Documentation, Release 0.1.11
266 Chapter 32. Bagel Design
CHAPTER 33
Bell Bagel Assembly
Ready-to-use parametric bell bagel assembly . It generates the belland the bagel parts.
267
Cnc25D Documentation, Release 0.1.11
268 Chapter 33. Bell Bagel Assembly
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible bell_bagel_assembly designs that can be bell_bagel_assembly() , run:
> python bell_bagel_assembly.py --run_self_test
33.1 Bell-Bagel-Assembly Parameters
The bell_bagel_assembly parameters are directly inherited from the Bell Design parameters and the Bagel Design
parameters.
33.2 Bell-Bagel-Assembly Parameter Dependency
33.2.1 axle_internal_diameter
The bell design and the bagel design have both the axle_internal_diameter parameter, respectly called
axle_internal_diameter andbagel_axle_internal_diameter . With ideal conditions, these two parameters get the same
value. But you might want to but slightly different values to adjust the fit of the middle_bagel into the bell axle internal
hole.
33.1. Bell-Bagel-Assembly Parameters 269
Cnc25D Documentation, Release 0.1.11
270 Chapter 33. Bell Bagel Assembly
CHAPTER 34
Crest Design
Ready-to-use parametric crest design. It is an optional part of the cross_cube assembly to get a motorized gimbal
system.
271
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible crest designs that can be crest() , run:
> python crest.py --run_self_test
34.1 Crest Parameters
Thecrest part inherit several parameters from Cross_Cube Design.
272 Chapter 34. Crest Design
Cnc25D Documentation, Release 0.1.11
34.1. Crest Parameters 273
Cnc25D Documentation, Release 0.1.11
274 Chapter 34. Crest Design
Cnc25D Documentation, Release 0.1.11
34.2 Crest Parameter Dependency
34.2.1 crest_cnc_router_bit_radius
The following parameter are related to the router_bit radius :
• crest_cnc_router_bit_radius
• gear_cnc_router_bit_radius
• gear_hollow_smoothing_radius
• cross_cube_cnc_router_bit_radius
• face_hollow_smoothing_radius
• top_hollow_smoothing_radius
Thecrest_cnc_router_bit_radius parameter guarantees the smallest value for all related router_bit radius parameters.
34.2. Crest Parameter Dependency 275
Cnc25D Documentation, Release 0.1.11
276 Chapter 34. Crest Design
CHAPTER 35
Cross_Cube Design
Ready-to-use parametric cross_cube design. It is a cross axle holder for gimbal.
277
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible cross_cube designs that can be cross_cube() , run:
> python cross_cube.py --run_self_test
35.1 Cross_Cube Parts and Parameters
Thecross_cube piece is composed out of the following flat parts:
278 Chapter 35. Cross_Cube Design
Cnc25D Documentation, Release 0.1.11
• face_A1
• face_A2
• face_B1
• face_B2
• top
35.1. Cross_Cube Parts and Parameters 279
Cnc25D Documentation, Release 0.1.11
280 Chapter 35. Cross_Cube Design
Cnc25D Documentation, Release 0.1.11
35.1. Cross_Cube Parts and Parameters 281
Cnc25D Documentation, Release 0.1.11
282 Chapter 35. Cross_Cube Design
Cnc25D Documentation, Release 0.1.11
35.1. Cross_Cube Parts and Parameters 283
Cnc25D Documentation, Release 0.1.11
284 Chapter 35. Cross_Cube Design
Cnc25D Documentation, Release 0.1.11
35.1. Cross_Cube Parts and Parameters 285
Cnc25D Documentation, Release 0.1.11
35.2 Cross_Cube Parameter Dependency
35.2.1 cross_cube_extra_cut_thickness
Thecross_cube_extra_cut_thickness parameter can be used to compensate the manufacturing process or to check the
3D assembly with FreeCAD. The default value is 0.0.
286 Chapter 35. Cross_Cube Design
CHAPTER 36
Gimbal Design
Ready-to-use parametric gimbal design. It is a mechanism with two degrees of freedom, that let’s adjusting the roll-
pitch orientation.
287
Cnc25D Documentation, Release 0.1.11
To get an overview of the possible gimbal designs that can be gimbal() , run:
> python gimbal.py --run_self_test
288 Chapter 36. Gimbal Design
Cnc25D Documentation, Release 0.1.11
36.1 Gimbal Parameters
Thegimbal mechanism is composed by two bell_bagel_assembly and one cross_cube with crests.
Thegimbal parameters are inherited from Cross_Cube Design and Bell Bagel Assembly. In addition to the cross_cube
parameters and bell_bagel parameters, you have the two roll-pitch angles.
36.1. Gimbal Parameters 289
Cnc25D Documentation, Release 0.1.11
36.2 Gimbal Construction
36.2.1 Material
Thebagels and the cross_cube are done with an harder material than the bell.
36.2.2 Assembly order
• make the cross_cube
• make the bellwithout the bagels
• make the motors
290 Chapter 36. Gimbal Design
Cnc25D Documentation, Release 0.1.11
• place the cross_cube into the bell-leg-axle-hole
• mount the bagels
• mount the motors
36.2. Gimbal Construction 291
Cnc25D Documentation, Release 0.1.11
292 Chapter 36. Gimbal Design
CHAPTER 37
Gimbal Details
37.1 Roll-Pitch angles
293
Cnc25D Documentation, Release 0.1.11
294 Chapter 37. Gimbal Details
Cnc25D Documentation, Release 0.1.11
37.1. Roll-Pitch angles 295
Cnc25D Documentation, Release 0.1.11
296 Chapter 37. Gimbal Details
Cnc25D Documentation, Release 0.1.11
37.1. Roll-Pitch angles 297
Cnc25D Documentation, Release 0.1.11
298 Chapter 37. Gimbal Details
Cnc25D Documentation, Release 0.1.11
37.1. Roll-Pitch angles 299
Cnc25D Documentation, Release 0.1.11
300 Chapter 37. Gimbal Details
CHAPTER 38
Planet_Carrier Design
Ready-to-use parametric planet_carrier design. It is composed of the rear and the front planet_carrier. It is used by
the Low_torque_transmission Design and High_torque_transmission Design.
To get an overview of the possible planet_carrier designs that can be planet_carrier() , run:
> python planet_carrier.py --run_self_test
38.1 Planet_Carrier Parameters
38.1.1 Overview
Theplanet_carrier is composed of the following parts:
• planet_carrier_rear
• planet_carrier_front
301
Cnc25D Documentation, Release 0.1.11
Theplanet_carrier_rear is the fusion of the rear plate the the middle bits. The planet_carrier_front is the simple plate
that can be fused with a sun-gear in a future design.
302 Chapter 38. Planet_Carrier Design
Cnc25D Documentation, Release 0.1.11
38.1.2 Diameters
38.1. Planet_Carrier Parameters 303
Cnc25D Documentation, Release 0.1.11
304 Chapter 38. Planet_Carrier Design
Cnc25D Documentation, Release 0.1.11
38.1.3 z-direction parameters
The parameters related to the extrusion size in the z-direction:
38.1. Planet_Carrier Parameters 305
Cnc25D Documentation, Release 0.1.11
38.2 Planet_Carrier Parameter Dependency
38.2.1 Diameters
• planet_center_circle_diameter
• planet_carrier_external_diameter
• planet_carrier_internal_diameter
306 Chapter 38. Planet_Carrier Design
CHAPTER 39
Low_torque_transmission Design
Ready-to-use parametric low-torque-transmission design. It is a reduction system based on a train of epicyclic-gearing.
The design includes the electric-motor holder for a cylindric or square format. The output is an hexagon on which you
can plug a gearwheel. It is a variant of Epicyclic Gearing Design
low_torque_transmission design characteristics:
• train of epicyclic-gearing of n-step (to reach a high reduction ratio)
• same epicyclic profile for the n-step (to get a simple gearring-holder desing)
• same epicyclic width for the n-1 first steps (only the last step might at its yield limits)
• epicyclic with 3 planets (for a more stable planet-holder)
• coaxial electric motor at the input (for a compact and reliable transmission)
• hexagon at the output (for an exchangeable output gearwheel)
• output axle hold on one side only (because on the other side, there is already the motor)
To get an overview of the possible low_torque_transmission designs that can be
low_torque_transmission() , run:
> python low_torque_transmission.py --run_self_test
39.1 Low_torque_transmission Parameters
39.1.1 Overview
The Low_torque_transmission is composed of the following parts
307
Cnc25D Documentation, Release 0.1.11
Thelow_torque_transmission inherits the parameters from the Gearring Design. The parameter epicyclic_step_nb sets
the number of epicyclic-steps.
39.1.2 z-direction parameters
The parameters related to the extrusion size in the z-direction:
308 Chapter 39. Low_torque_transmission Design
Cnc25D Documentation, Release 0.1.11
39.1. Low_torque_transmission Parameters 309
Cnc25D Documentation, Release 0.1.11
310 Chapter 39. Low_torque_transmission Design
Cnc25D Documentation, Release 0.1.11
39.1.3 Sun and planet parameters
39.1. Low_torque_transmission Parameters 311
Cnc25D Documentation, Release 0.1.11
312 Chapter 39. Low_torque_transmission Design
Cnc25D Documentation, Release 0.1.11
39.1.4 Planet-carrier parameters
39.1. Low_torque_transmission Parameters 313
Cnc25D Documentation, Release 0.1.11
314 Chapter 39. Low_torque_transmission Design
Cnc25D Documentation, Release 0.1.11
39.2 Low_torque_transmission Parameter Dependency
39.2.1 hexagon_width
Theoutput_hexagon must into the output_holder . But also the output_front_planet_carrier_width must be inside the
output-cover to guarantee enough slack between the *output_planet and the output_cover . So we get the relations:
39.2. Low_torque_transmission Parameter Dependency 315
Cnc25D Documentation, Release 0.1.11
output_cover_width + hexagon_width > output_holder_width
hexagon_width < output_holder_width
39.2.2 input_slack
The input_slack parameter sets some play between the motor_holder and the first rear_planet_carrier . Notice that
this value is affected by the length of the output axle.
316 Chapter 39. Low_torque_transmission Design
CHAPTER 40
Low_torque_transmission Details
317
Cnc25D Documentation, Release 0.1.11
318 Chapter 40. Low_torque_transmission Details
CHAPTER 41
High_torque_transmission Design
Ready-to-use parametric high-torque-transmission design. It is a reduction system based on a train of epicyclic-
gearing. The design includes an input and an output gearwheel as well as a central axle to support high strength on the
input/output gearwheels. It is a variant of Epicyclic Gearing Design.
319
Cnc25D Documentation, Release 0.1.11
320 Chapter 41. High_torque_transmission Design
CHAPTER 42
Indices and tables
• genindex
• modindex
• search
321
|
"===================================================================================================(...TRUNCATED) |
"======================================================================================\n\n1.1\n1.2\(...TRUNCATED) |
"==========================================================================\n\n1.1\n1.2\n1.2.1\n1.2.(...TRUNCATED) |
"=====================================================================\n\nfind all the freecad docum(...TRUNCATED) |
"===============================================================================\n\n2025-05-14 15:49(...TRUNCATED) |
"========================================================================\n\nSOURCE CODE FILE: fine-(...TRUNCATED) |
"===================================================================================================(...TRUNCATED) |
"===================================================================================================(...TRUNCATED) |
"===================================================================================================(...TRUNCATED) |
End of preview. Expand
in Data Studio
README.md exists but content is empty.
- Downloads last month
- 3