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gcodepreview-openscad_0_6.tex
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gcodepreview-openscad_0_6.tex
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% gcodepreview.tex
% Author: William F. Adams (willadams at aol dot com)
% Copyright 2021--24 William F. Adams
%
% This work may be distributed and/or modified under the
% conditions of the GNU LESSER GENERAL PUBLIC LICENSE
% Version 2.1, February 1999
%
% This work consists of the files listed in the README file.
%
%
%
\documentclass{ltxdoc}
%https://tex.stackexchange.com/questions/722886/how-to-write-out-multiple-text-files-from-multiple-instances-of-latex-environmen
\usepackage{literati}
\usepackage[paper=legalpaper,left=1.75in,right=0.75in,top=1in,bottom=1in]{geometry}
\begin{document}
%\DoNotIndex{\bullet}
%\changes{v0.61}{2024/09/08}{modules and tests}
\def\fileversion{v0.61} \def\filedate{2024/09/08}
%\changes{v0.6}{2024/08/30}{modules and setupstock}
%\def\fileversion{v0.6} \def\filedate{2024/08/30}
%\changes{v0.5}{2024/08/10}{DXFs and images}
%\def\fileversion{v0.5} \def\filedate{2024/08/10}
%\changes{v0.4}{2024/07/28}{Literary re-write}
%\def\fileversion{v0.4} \def\filedate{2024/07/28}
%\changes{v0.3}{2024/07/01}{Curves and roundover tooling}
%\def\fileversion{v0.3} \def\filedate{2024/07/01}
%\changes{v0.2}{2024/04/12}{Initial conversion to DTX}
%\def\dtxfile{gcodepreview.dtx}
\title{The gcodepreview OpenSCAD library\thanks{This
file (\texttt{\jobname}) has version number \fileversion, last revised
\filedate.}}
\author{%
Author: William F. Adams\\
\texttt{willadams at aol dot com}
}
\date{\filedate}
\maketitle
\begin{abstract}
\noindent The gcodepreview library allows using OpenPythonSCAD to move a tool in lines
and arcs and output dxf and G-code files so as to work as a CAD/\allowbreak CAM program
for CNC.
\end{abstract}
%\enlargethispage{\baselineskip}
\tableofcontents
\clearpage
\section{readme.md}
\begin{readme}
# gcodepreview
OpenSCAD library for moving a tool in lines and arcs
so as to model how a part would be cut using G-Code,
so as to allow OpenSCAD to function as a compleat
CAD/CAM solution for subtractive 3-axis CNC (mills
and routers) by writing out G-code (in some cases
toolpaths which would not normally be feasible),
and to write out DXF files which may be imported
into a traditional CAM program to create toolpaths.
Updated to make use of Python in OpenSCAD:[^rapcad]
[^rapcad]: Previous versions had used RapCAD, so as to take advantage of the writeln command, which has since been re-written in Python.
https://pythonscad.org/ (previously this was http://www.guenther-sohler.net/openscad/ )
A BlockSCAD file for the initial version of the
main modules is available at:
https://www.blockscad3d.com/community/projects/1244473
The project is discussed at:
https://forum.makerforums.info/t/g-code-preview-using-openscad-rapcad/85729
and
https://forum.makerforums.info/t/openscad-and-python-looking-to-finally-be-resolved/88171
and
https://willadams.gitbook.io/design-into-3d/programming
Since it is now programmed using Literate Programming
(initially a .dtx, now a .tex file) there is a PDF:
https://github.com/WillAdams/gcodepreview/blob/main/gcodepreview.pdf
which includes all of the source code with formatted
commentary.
The files for this library are:
- gcodepreview.py (gcpy) --- the Python functions and variables
- pygcodepreview.scad (pyscad) --- the Python functions wrapped in OpenSCAD
- gcodepreview.scad (gcpscad) --- OpenSCAD modules and variables
- gcodepreview_template.scad (gcptmpl) --- example file
- cut2Dshapes.scad (cut2D) --- code for cutting 2D shapes
Place the files in C:\Users\\\~\Documents\OpenSCAD\libraries and call as:[^libraries]
[^libraries]: C:\Users\\\~\Documents\RapCAD\libraries is deprecated since RapCAD is no longer needed since Python is now used for writing out files)
use <gcodepreview.py>;
use <pygcodepreview.scad>;
include <gcodepreview.scad>;
Note that it is necessary to use the first two files
(this allows loading the Python commands and then
wrapping them in OpenSCAD commands) and then include
the last file (which allows using OpenSCAD variables
to selectively implement the Python commands via their
being wrapped in OpenSCAD modules) and define
variables which match the project and then use
commands such as:
opengcodefile(Gcode_filename);
opendxffile(DXF_filename);
difference() {
setupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
movetosafez();
toolchange(squaretoolno,speed * square_ratio);
begintoolpath(0,0,0.25);
beginpolyline(0,0,0.25);
cutoneaxis_setfeed("Z",-1,plunge*square_ratio);
addpolyline(stocklength/2,stockwidth/2,-stockthickness);
cutwithfeed(stocklength/2,stockwidth/2,-stockthickness,feed);
endtoolpath();
endpolyline();
}
closegcodefile();
closedxffile();
which makes a G-code file:
but one which could only be sent to a machine so as to
cut only the softest and most yielding of materials
since it makes a single full-depth pass, and of which
has a matching DXF which may be imported into a
CAM tool --- but which it is not directly possible
to assign a toolpath in readily available CAM tools
(since it varies in depth from beginning-to-end).
Importing this DXF and actually cutting it
is discussed at:
https://forum.makerforums.info/t/rewriting-gcodepreview-with-python/88617/14
Tool numbers match those of tooling sold by Carbide 3D
(ob. discl., I work for them).
Comments are included in the G-code to match those
expected by CutViewer.
A complete example file is: gcodepreview_template.scad
and another example is openscad_gcodepreview_cutjoinery.tres.scad
which is made from an OpenSCAD Graph Editor file:
Version 0.1 supports setting up stock, origin, rapid
positioning, making cuts, and writing out matching
G-code, and creating a DXF with polylines.
Added features since initial upload:
- endpolyline(); --- this command allows ending one polyline so as to allow multiple lines in a DXF
- separate dxf files are written out for each tool where tool is ball/square/V and small/large (10/31/23)
- re-writing as a Literate Program using the LaTeX package docmfp (begun 4/12/24)
- support for additional tooling shapes such as dovetail and keyhole tools
Version 0.2 adds support for arcs
- DXF: support for arcs (which may be used to make circles) (6/1/24)
- Specialty toolpaths such as Keyhole which may be used for dovetail as well as keyhole cutters
Version 0.3
- Support for curves along the 3rd dimension
- support for roundover tooling
Version 0.4
- Rewrite using literati documentclass, suppression of SVG code
- dxfrectangle (without G-code support)
Version 0.5
- more shapes
- consolidate rectangles, arcs, and circles in gcodepreview.scad
Version 0.6
- notes on modules
- change file for setupstock
Version 0.7
- reduce usage of tool numbers
- validate all code so that it runs without errors from sample file
Possible future improvements:
- support for additional tooling shapes such as tapered ball-nose tools or lollipop cutters or thread-cutting tools
- G-code: support for G2/G3 arcs and circles
- G-code: import external tool libraries and feeds and speeds from JSON or CSV files ---
- general coding improvements --- current coding style is quite prosaic
- additional generalized modules for cutting out various shapes/geometries
Note for G-code generation that it is up to the user
to implement Depth per Pass so as to not take a
single full-depth pass. Working from a DXF of course
allows one to off-load such considerations to a
specialized CAM tool.
Deprecated feature:
- exporting SVGs --- while this was begun, it turns out that these would be written out upside down due to coordinate system differences between OpenSCAD/DXFs and SVGs requiring managing the inversion of the coordinate system (it is possible that METAPOST, which shares the same orientation and which can write out SVGs will be used instead for future versions)
\end{readme}
\clearpage
\section{gcodepreview}
This library for OpenPythonSCAD works by using Python code as a back-end so as to persistently store
and access variables, and to write out files while both modeling the motion of a 3-axis CNC machine
and if desired, writing out DXF and/or G-code files (as opposed to the normal technique of
rendering to a 3D model and writing out an STL). Doing so requires a total of three files:
\begin{itemize}
\item A Python file: gcodepreview.py (\texttt{gcpy}) --- this will have variables in the
traditional sense which may be used for tracking machine position and so forth
\item An OpenSCAD file: pygcodepreview.scad (\texttt{pyscad}) --- which wraps the Python code
in OpenSCAD
\item An OpenSCAD file: gcodepreview.scad (\texttt{gcpscad}) --- which uses the other two files
and which is \texttt{include}d allowing it to access OpenSCAD variables for branching
\end{itemize}
Note that this architecture requires that many modules are essentially ``Dispatchers'' which
pass information from one aspect of the environment to another.
\subsection{gcodepreviewtemplate.scad}
The various commands are shown all together in a template so as to provide examples of usage,
and to ensure that the various files are used/included as necessary, all variables are set up
with the correct names, and that files are opened before being written to, and that each
is closed at the end.
Note that while the file seems overly verbose, it specifically incorporates variables
for each tool shape, possibly in two different sizes, and a feed rate parameter or ratio
for each, which may be used (by setting a tool \#) or ignored (by leaving the variable
at zero (0).
It should be that this section is all the documentation which some users will need.
(and arguably is still too much). The balance of the document after this section
shows all the code and implementation details.
%Creating a template from memory, the file should be something like:
%
%List of all tools
%chipload for each tool
%Depth per Pass for each tool
%scaling factor for chipload to arrive at feeds and speeds
%Booleans for generateDXF/Gcode, 3D Preview, assembly or parts or drop-down list of parts, &c.
%
%setupstock --- should this open gcode/dxf files as well?
%
%toolchange to first tool
%
%Rapid to location of first cut
%cutline/cutarc --- iterate as needed
%Rapid to safe height
%
%Program END --- should close gcode/DXF files and include rapid to safe height and rapid to back
\lstset{firstnumber=1}%\thegcptmpl}
\begin{writecode}{w}{gcodepreviewtemplate.scad}{scad}
//!OpenSCAD
use <gcodepreview.py>;
use <pygcodepreview.scad>;
include <gcodepreview.scad>;
$fa = 2;
$fs = 0.125;
/* [Export] */
Base_filename = "export";
/* [Export] */
generatedxf = true;
/* [Export] */
generategcode = true;
///* [Export] */
//generatesvg = false;
/* [CAM] */
toolradius = 1.5875;
/* [CAM] */
large_ball_tool_no = 0; // [0:0,111:111,101:101,202:202]
/* [CAM] */
large_square_tool_no = 0; // [0:0,112:112,102:102,201:201]
/* [CAM] */
large_V_tool_no = 0; // [0:0,301:301,690:690]
/* [CAM] */
small_ball_tool_no = 0; // [0:0,121:121,111:111,101:101]
/* [CAM] */
small_square_tool_no = 102; // [0:0,122:122,112:112,102:102]
/* [CAM] */
small_V_tool_no = 0; // [0:0,390:390,301:301]
/* [CAM] */
KH_tool_no = 0; // [0:0,374:374,375:375,376:376,378]
/* [CAM] */
DT_tool_no = 0; // [0:0,814:814]
/* [CAM] */
Roundover_tool_no = 56125; // [56125:56125, 56142:56142,312:312, 1570:1570]
/* [CAM] */
MISC_tool_no = 0; //
/* [Feeds and Speeds] */
plunge = 100;
/* [Feeds and Speeds] */
feed = 400;
/* [Feeds and Speeds] */
speed = 16000;
/* [Feeds and Speeds] */
small_square_ratio = 0.75; // [0.25:2]
/* [Feeds and Speeds] */
small_ball_ratio = 0.75; // [0.25:2]
/* [Feeds and Speeds] */
large_ball_ratio = 1.0; // [0.25:2]
/* [Feeds and Speeds] */
small_V_ratio = 0.625; // [0.25:2]
/* [Feeds and Speeds] */
large_V_ratio = 0.875; // [0.25:2]
/* [Feeds and Speeds] */
KH_ratio = 0.75; // [0.25:2]
/* [Feeds and Speeds] */
DT_ratio = 0.75; // [0.25:2]
/* [Feeds and Speeds] */
RO_ratio = 0.5; // [0.25:2]
/* [Feeds and Speeds] */
MISC_ratio = 0.5; // [0.25:2]
/* [Stock] */
stocklength = 219;
/* [Stock] */
stockwidth = 150;
/* [Stock] */
stockthickness = 8.35;
/* [Stock] */
zeroheight = "Top"; // [Top, Bottom]
/* [Stock] */
stockorigin = "Center"; // [Lower-Left, Center-Left, Top-Left, Center]
/* [Stock] */
retractheight = 9;
filename_gcode = str(Base_filename, ".nc");
filename_dxf = str(Base_filename);
opengcodefile(filename_gcode);
opendxffile(filename_dxf);
difference() {
setupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
movetosafez();
toolchange(small_square_tool_no,speed * small_square_ratio);
begintoolpath(0,0,0.25);
cutoneaxis_setfeed("Z",0,plunge*small_square_ratio);
cutwithfeed(stocklength/2,stockwidth/2,-stockthickness,feed);
dxfpolyline(getxpos(),getypos(),stocklength/2,stockwidth/2, small_square_tool_no);
endtoolpath();
rapid(-(stocklength/4-stockwidth/16),stockwidth/4,0);
cutoneaxis_setfeed("Z",-stockthickness,plunge*small_square_ratio);
cutarcNECCdxf(-stocklength/4, stockwidth/4+stockwidth/16, -stockthickness, -stocklength/4, stockwidth/4, stockwidth/16, small_square_tool_no);
cutarcNWCCdxf(-(stocklength/4+stockwidth/16), stockwidth/4, -stockthickness, -stocklength/4, stockwidth/4, stockwidth/16, small_square_tool_no);
cutarcSWCCdxf(-stocklength/4, stockwidth/4-stockwidth/16, -stockthickness, -stocklength/4, stockwidth/4, stockwidth/16, small_square_tool_no);
cutarcSECCdxf(-(stocklength/4-stockwidth/16), stockwidth/4, -stockthickness, -stocklength/4, stockwidth/4, stockwidth/16, small_square_tool_no);
rapid(getxpos(),getypos(),stockthickness);
toolchange(KH_tool_no,speed * KH_ratio);
rapid(-stocklength/8,-stockwidth/4,0);
cutkeyhole_toolpath((stockthickness), (stockthickness), "N", stockwidth/8, KH_tool_no);
rapid(getxpos(),getypos(),stockthickness);
rapid(-stocklength/4,-stockwidth/4,0);
cutkeyhole_toolpath((stockthickness), (stockthickness), "S", stockwidth/8, KH_tool_no);
rapid(getxpos(),getypos(),stockthickness);
rapid(-stocklength/4,-stockwidth/8,0);
cutkeyhole_toolpath((stockthickness), (stockthickness), "E", stockwidth/8, KH_tool_no);
rapid(getxpos(),getypos(),stockthickness);
rapid(-stocklength/8,-stockwidth/8*3,0);
cutkeyhole_toolpath((stockthickness), (stockthickness), "W", stockwidth/8, KH_tool_no);
rapid(getxpos(),getypos(),stockthickness);
toolchange(DT_tool_no,speed * DT_ratio);
rapid(0,-(stockwidth/2+tool_diameter(DT_tool_no,0)),0);
cutoneaxis_setfeed("Z",-stockthickness,plunge*DT_ratio);
cutwithfeed(0,-(stockwidth/4),-stockthickness,feed*DT_ratio);
rapid(0,-(stockwidth/2+tool_diameter(DT_tool_no,0)),-stockthickness);
rapid(getxpos(),getypos(),stockthickness);
toolchange(Roundover_tool_no, speed * RO_ratio);
rapid(-(stocklength/2),-(stockwidth/2),0);
cutoneaxis_setfeed("Z",-4.509,plunge*RO_ratio);
cutroundovertool(-(stocklength/2++0.507/2), -(stockwidth/2+0.507/2), -4.509, stocklength/2+0.507/2, -(stockwidth/2+0.507/2), -4.509, 0.507/2, 4.509);
cutroundover(stocklength/2+0.507/2, -(stockwidth/2+0.507/2), -4.509, stocklength/2+0.507/2, stockwidth/2+0.507/2, -4.509, 1570);
cutroundover(stocklength/2+0.507/2, stockwidth/2+0.507/2, -4.509, -(stocklength/2+0.507/2), stockwidth/2+0.507/2, -4.509, 1570);
cutroundover(-(stocklength/2+0.507/2), stockwidth/2+0.507/2, -4.509, -(stocklength/2+0.507/2), -(stockwidth/2+0.507/2), -4.509, 1570);
for (i = [0 : abs(1) : 80]) {
cutwithfeed(stocklength/4,-stockwidth/4,-stockthickness/4,feed);
cutwithfeed(stocklength/8+(stocklength/256*i),-stockwidth/2,-stockthickness*3/4,feed);
}
closegcodefile();
closedxffile();
\end{writecode}
\addtocounter{gcptmpl}{145}
%Note that the line:
%
%\begin{verbatim}
%toolchange(small_square_tool_no,speed * square_ratio);
%\end{verbatim}
%
%\noindent may be commented out --- whether or no it is actually necessary will need to be
%decided upon.
\subsection{Implementation}
Each file will begin with a suitable comment indicating the file type and suitable notes/comments:
\begin{writecode}{w}{gcodepreview.py}{python}
#!/usr/bin/env python
#icon "C:\Program Files\PythonSCAD\bin\openscad.exe" --trust-python
#Currently tested with 2024.09.03 and Python 3.11
#gcodepreview 0.61, see gcodepreview.scad
\end{writecode}
\addtocounter{gcpy}{6}
\begin{writecode}{w}{pygcodepreview.scad}{scad}
//!OpenSCAD
//gcodepreview 0.61, see gcodepreview.scad
\end{writecode}
\addtocounter{pyscad}{5}
\begin{writecode}{w}{gcodepreview.scad}{scad}
//!OpenSCAD
//gcodepreview 0.61
//
//used via use <gcodepreview.py>;
// use <pygcodepreview.scad>;
// include <gcodepreview.scad>;
//
\end{writecode}
\addtocounter{gcpscad}{10}
The original implementation in \textsf{RapSCAD} used a command
\DescribeRoutine{writeln} --- fortunately,
this command is easily re-created in Python:
\lstset{firstnumber=\thegcpy}
\begin{writecode}{a}{gcodepreview.py}{python}
def writeln(*arguments):
line_to_write = ""
for element in arguments:
line_to_write += element
f.write(line_to_write)
f.write("\n")
\end{writecode}
\addtocounter{gcpy}{7}
\noindent which command will accept a series of arguments and then write them out to a file
object.
\subsection{Position and Variables}
In modeling the machine motion and G-code it will be necessary to have the machine track
several variables for machine position, current tool, and depth in toolpath.
This will be done using paired functions (which will set and return the
matching variable) and a matching (global) variable, as well as additional functions for
setting the matching variable(s).
\begin{samepage}
The first such variables are for XYZ position:
\begin{itemize}
\item \DescribeVariable{mpx}
\item \DescribeVariable{mpy}
\item \DescribeVariable{mpz}
\end{itemize}
\end{samepage}
\begin{samepage}
\noindent Similarly, for some toolpaths it will be necessary to track the depth along the Z-axis
as the toolpath is cut out:
\begin{itemize}
\item \DescribeVariable{tpz}
\end{itemize}
\end{samepage}
\begin{samepage}
\noindent It will further be necessary to have a variable for the current tool:
\begin{itemize}
\item \DescribeVariable{currenttool}
\end{itemize}
\end{samepage}
Note that the \verb|currenttool| variable should always be used for any specification
of a tool, being read in whenever a tool is to be made use of, or a parameter or aspect
of the tool needs to be used in a calculation. %(Which implies that
%the tool parameters in modules other then \verb|toolchange(tool_number, speed);|
%should be removed.)
For each intended command it will be necessary to implement an appropriate aspect in each file.
The Python file will manage the Python variables and handle things which can only be done in
Python, while there will be two OpenSCAD files as noted above, one which calls the Python code
(this will be \texttt{use}d), while the other will be able to access
and use OpenSCAD variables, as well as implement Customizer options
(this will be \texttt{include}d).
\subsection{Output files}
\subsubsection{G-code and modules and commands}
Each module/command will write out certain G-code commands:
\bigskip
\noindent \begin{tabular}{@{}ll@{}} \toprule
Command/Module & G-code \\ \midrule
\texttt{opengcodefile(...);}
\texttt{setupstock(...)} & \texttt{(export.nc)} \\
& \texttt{(stockMin: -109.5, -75mm, -8.35mm)}\\
& \texttt{(stockMax:109.5mm, 75mm, 0.00mm)}\\
& \texttt{(STOCK/BLOCK, 219, 150, 8.35, 109.5, 75, 8.35)}\\
& \texttt{G90}\\
& \texttt{G21} \\ \midrule
\texttt{movetosafez()} & \texttt{(Move to safe Z to avoid workholding)}\\
& \texttt{G53G0Z-5.000}\\ \midrule
\texttt{toolchange(...);} & \texttt{(TOOL/MILL,3.17, 0.00, 0.00, 0.00)} \\
& \texttt{M6T102} \\
& \texttt{M03S16000} \\ \midrule
\verb|cutoneaxis_setfeed(...);| & \texttt{(PREPOSITION FOR RAPID PLUNGE)}\\
& \texttt{G0X0Y0} \\
& \texttt{Z0.25} \\
& \texttt{G1Z0F100} \\
& \texttt{G1 X109.5 Y75 Z-8.35F400} \\
& \texttt{Z9}\\
\texttt{cutwithfeed(...);}\\ \midrule
\texttt{closegcodefile();} & \texttt{M05}\\
& \texttt{M02}\\
\bottomrule
\end{tabular}
\bigskip
%(Toolpath)
%M05
\noindent Conversely, the G-code commands which are supported are generated by the following modules:
\bigskip
\noindent \begin{tabular}{@{}ll@{}} \toprule
G-code & Command/Module \\ \midrule
\verb|(Design File: )| & \texttt{opengcodefile(...);}
\texttt{setupstock(...)}\\
\verb|(stockMin:0.00mm, -152.40mm, -34.92mm)| \\
\verb|(stockMax:109.50mm, -77.40mm, 0.00mm)| \\
\verb|(STOCK/BLOCK,109.50, 75.00, 34.92,0.00, 152.40, 34.92)| \\
\verb|G90| \\
\verb|G21| \\ \midrule
\verb|(Move to safe Z to avoid workholding)| & \texttt{movetosafez()} \\
\verb|G53G0Z-5.000| \\ \midrule
\verb|(Toolpath: Contour Toolpath 1)| & \texttt{toolchange(...);}\\
\verb|M05| \\
\verb|(TOOL/MILL,3.17, 0.00, 0.00, 0.00)| \\
\verb|M6T102| \\
\verb|M03S10000| \\ \midrule
\verb|(PREPOSITION FOR RAPID PLUNGE)| & \texttt{writecomment(...)}\\ \midrule
\verb|G0X0.000Y-152.400| & \texttt{rapid(...)}\\
\verb|Z0.250| & \texttt{rapid(...)}\\ \midrule
\verb|G1Z-1.000F203.2| & \texttt{cutwithfeed(...);}\\
\verb|X109.500Y-77.400F508.0| & \texttt{cutwithfeed(...);} \\
\verb|X57.918Y16.302Z-0.726|\\
\verb|Y22.023Z-1.023|\\
\verb|X61.190Z-0.681|\\
\verb|Y21.643|\\
\verb|X57.681|\\
\verb|Z12.700|\\ \midrule
\verb|M05| & \texttt{closegcodefile();}\\
\verb|M02|\\
\bottomrule
\end{tabular}
\bigskip
The implication here is that it should be possible to read in a G-code file, and for each
line/command instantiate a matching command so as to create a 3D model/preview of the file.
\subsubsection{DXF}
Elements in DXFs are represented as lines or arcs. A minimal file showing both:
\begin{verbatim}
0
SECTION
2
ENTITIES
0
LWPOLYLINE
90
2
70
0
43
0
10
-31.375
20
-34.9152
10
-31.375
20
-18.75
0
ARC
10
-54.75
20
-37.5
40
4
50
0
51
90
0
ENDSEC
0
EOF
\end{verbatim}
\subsection{Modules}
Note that as a convention, where it is necessary for a module to coordinate between
Python~and OpenSCAD, in certain cases it will be necessary for there to be three separate
versions: a \texttt{p}<foo>~Python definition for the manipulation of Python variables and
any file routines, an \texttt{o}<foo> OpenSCAD module which will wrap up the Python
function call, and lastly a <foo> OpenSCAD module which will be \texttt{<include>}d
so as to be able to make use of OpenSCAD variables.
In natural languages such as English, there is an order to various parts of speech such as
adjectives
%(determiner, opinion/observation, size, age, shape, color, origin/nationality,
%material, purpose/qualifier)
--- since various prefixes and suffixes will be used for module names, having a consistent
ordering/usage will help in consistency and make expression clearer.
The ordering should be: sequence, action, function, parameter, filetype
\begin{outline}
\1 Both prefix and suffix
\2 \texttt{dxf} (action (write out dxf file), filetype)
\1 Prefixes
\2 \texttt{begin} (sequence)
\2 \texttt{continue} (sequence)
\2 \texttt{end} (sequence)
\2 \texttt{cut} (action)
\2 \texttt{move} (action)
\2 \texttt{rapid} (action)
\2 \texttt{open} (action)
\2 \texttt{close} (action)
\2 \texttt{set} (action/function)
\1 Suffixes
\2 \texttt{feed} (parameter)
\2 \texttt{gcode} (filetype)
\2 \texttt{polyline) (file (element))}
\end{outline}
%\subsubsection{Interfaces}
For the sake of convenience, all user-facing modules will be listed here with their interface
requirements/variables. Where appropriate, modules which interact will be listed together.
%\lstset{firstnumber=1}
%\begin{writecode}{w}{interfaces.txt}{txt}
\begin{verbatim}
begincutdxf(rh, ex, ey, ez, fr); and continuecutdxf(ex, ey, ez, fr);
beginpolyline(bx,by,bz); and addpolyline(bx,by,bz); and closepolyline();
begintoolpath(bx,by,bz); and endtoolpath();
current_tool(); [function]
cut(ex, ey, ez);
cutoneaxis_setfeed(axis,depth,feed);
cutwithfeed(ex, ey, ez, feed);
cutarcNECCdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcNWCCdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcSWCCdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcSECCdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcNECWdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcSECWdxf(ex, ey, ez, xcenter, ycenter, radius);
cutarcSWCWdxf(ex, ey, ez, xcenter, ycenter, radius);
cutkeyhole_toolpath(kh_start_depth, kh_max_depth, kht_direction, kh_distance);
cutoutrectangledxf(bx, by, bz, rwidth, rheight, rdepth);
cutrectangledxf(bx, by, bz, rwidth, rheight, rdepth);
cutrectangleoutlinedxf(bx, by, bz, rwidth, rheight, rdepth);
cutroundover(bx, by, bz, ex, ey, ez);
dxfarc(xcenter, ycenter, radius, anglebegin, endangle);
dxfpolyline(xbegin,ybegin,xend,yend);
movetosafeheight();
movetosafez();
opendxffile(fn); and closedxffile();
opengcodefile(fn); and closegcodefile();
rapidbx(bx, by, bz, ex, ey, ez);
rapid(ex, ey, ez);
rectangleoutlinedxf(bx, by, bz, rwidth, rheight);
setupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
setxpos(newxpos);
setypos(newypos);
setzpos(newzpos);
settzpos(newtzpos);
toolchange(tool_number,speed);
tool_diameter(td_tool, td_depth); [function]
tool_radius(td_tool, td_depth); [function]
writecomment(comment);
\end{verbatim}
%\end{writecode}
Principles for naming modules (and variables):
\begin{itemize}
\item minimize use of underscores (for convenience sake, underscores are not used for index entries)
\item identify which aspect of the project structure is being worked with (\texttt{cut}(ting),
\texttt{dxf}, \texttt{gcode}, \texttt{tool} management, etc.) and esp. note the use of
\texttt{o}(penscad) and \texttt{p}(ython) as prefixes
\end{itemize}
Structurally, this will typically look like:
\begin{verbatim}
The user-facing module is \DescribeRoutine{FOOBAR}
\lstset{firstnumber=\thegcpscad}
\begin{writecode}{a}{gcodepreview.scad}{scad}
module FOOBAR(...) {
oFOOBAR(...);
}
\end{writecode}
\addtocounter{gcpscad}{4}
which calls the internal OpenSCAD Module \DescribeSubroutine{FOOBAR}{oFOOBAR}
\begin{writecode}{a}{pygcodepreview.scad}{scad}
module oFOOBAR(...) {
pFOOBAR(...);
}
\end{writecode}
\addtocounter{pyscad}{4}
which in turn calls the internal Python definitioon \DescribeSubroutine{FOOBAR}{pFOOBAR}
\lstset{firstnumber=\thegcpy}
\begin{writecode}{a}{gcodepreview.py}{python}
def pFOOBAR (...)
...
\end{writecode}
\addtocounter{gcpy}{3}
\end{verbatim}
Further note that this definition will not be necessary for some later modules since they are
in turn calling internal modules which already use this structure.
\subsubsection{Initial Modules}
The first such routine, (actually a subroutine, see \DescribeRoutine{setupstock})
\DescribeSubroutine{setupstock}{psetupstock} will be appropriately enough,
to set up the stock, and perform other initializations --- in Python all that needs
to be done is to set the value of the persistent (Python) variables:
\lstset{firstnumber=\thegcpy}
\begin{writecode}{a}{gcodepreview.py}{python}
def psetupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin):
global mpx
mpx = float(0)
global mpy
mpy = float(0)
global mpz
mpz = float(0)
global tpz
tpz = float(0)
global currenttool
currenttool = 102
\end{writecode}
\addtocounter{gcpy}{12}
Note that while the \#102 is declared as a default tool, while it was originally necessary
to call a tool change after invoking \verb|setupstock| in the 2024.09.03 version of
PythonSCAD this requirement went away when a but which interfered with persistently setting
a variable directly was fixed.
The intermediary OpenSCAD code, \DescribeSubroutine{setupstock}{osetupstock} simply
calls the Python version. Note that while the parameters are passed all the way down
(for consistency) they are not used.
\lstset{firstnumber=\thepyscad}
\begin{writecode}{a}{pygcodepreview.scad}{scad}
module osetupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin) {
psetupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
}
\end{writecode}
\addtocounter{pyscad}{4}
The OpenSCAD code, \DescribeRoutine{setupstock} requires that the user set parameters
for stock dimensions and so forth, and will create comments in the G-code which incorporate
the stock dimensions and its position relative to the zero as set relative to the stock.
The internal variable \verb|stockorigin| is used in an \verb|<if then else>| structure to position
the 3D model of the stock.
\lstset{firstnumber=\thegcpscad}
\begin{writecode}{a}{gcodepreview.scad}{scad}
module setupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin) {
osetupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
//initialize default tool and XYZ origin
osettool(102);
oset(0,0,0);
if (zeroheight == "Top") {
if (stockorigin == "Lower-Left") {
translate([0, 0, (-stockthickness)]){
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owritethree("(stockMin:0.00mm, 0.00mm, -",str(stockthickness),"mm)");
owritefive("(stockMax:",str(stocklength),"mm, ",str(stockwidth),"mm, 0.00mm)");
owritenine("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", 0.00, 0.00, ",str(stockthickness),")");
}
}
}
else if (stockorigin == "Center-Left") {
translate([0, (-stockwidth / 2), -stockthickness]){
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owritefive("(stockMin:0.00mm, -",str(stockwidth/2),"mm, -",str(stockthickness),"mm)");
owritefive("(stockMax:",str(stocklength),"mm, ",str(stockwidth/2),"mm, 0.00mm)");
owriteeleven("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", 0.00, ",str(stockwidth/2),", ",str(stockthickness),")");
}
}
} else if (stockorigin == "Top-Left") {
translate([0, (-stockwidth), -stockthickness]){
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owritefive("(stockMin:0.00mm, -",str(stockwidth),"mm, -",str(stockthickness),"mm)");
owritethree("(stockMax:",str(stocklength),"mm, 0.00mm, 0.00mm)");
owriteeleven("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", 0.00, ",str(stockwidth),", ",str(stockthickness),")");
}
}
}
else if (stockorigin == "Center") {
//owritecomment("Center");
translate([(-stocklength / 2), (-stockwidth / 2), -stockthickness]){
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owriteseven("(stockMin: -",str(stocklength/2),", -",str(stockwidth/2),"mm, -",str(stockthickness),"mm)");
owritefive("(stockMax:",str(stocklength/2),"mm, ",str(stockwidth/2),"mm, 0.00mm)");
owritethirteen("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", ",str(stocklength/2),", ", str(stockwidth/2),", ",str(stockthickness),")");
}
}
}
} else if (zeroheight == "Bottom") {
//owritecomment("Bottom");
if (stockorigin == "Lower-Left") {
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owriteone("(stockMin:0.00mm, 0.00mm, 0.00mm)");
owriteseven("(stockMax:",str(stocklength),"mm, ",str(stockwidth),"mm, ",str(stockthickness),"mm)");
owriteseven("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),",0.00, 0.00, 0.00)");
}
} else if (stockorigin == "Center-Left") {
translate([0, (-stockwidth / 2), 0]){
cube([stocklength, stockwidth, stockthickness], center=false);
if (generategcode == true) {
owritethree("(stockMin:0.00mm, -",str(stockwidth/2),"mm, 0.00mm)");
owriteseven("(stockMax:",str(stocklength),"mm, ",str(stockwidth/2),"mm, ",str(stockthickness),"mm)");
owritenine("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),",0.00, ",str(stockwidth/2),", 0.00)");
}
}
} else if (stockorigin == "Top-Left") {
translate([0, (-stockwidth), 0]){
cube([stocklength, stockwidth, stockthickness], center=false);
}
if (generategcode == true) {
owritethree("(stockMin:0.00mm, -",str(stockwidth),"mm, 0.00mm)");
owritefive("(stockMax:",str(stocklength),"mm, 0.00mm, ",str(stockthickness),"mm)");
owritenine("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", 0.00, ", str(stockwidth),", 0.00)");
}
} else if (stockorigin == "Center") {
translate([(-stocklength / 2), (-stockwidth / 2), 0]){
cube([stocklength, stockwidth, stockthickness], center=false);
}
if (generategcode == true) {
owritefive("(stockMin:-",str(stocklength/2),", -",str(stockwidth/2),"mm, 0.00mm)");
owriteseven("(stockMax:",str(stocklength/2),"mm, ",str(stockwidth/2),"mm, ",str(stockthickness),"mm)");
owriteeleven("(STOCK/BLOCK, ",str(stocklength),", ",str(stockwidth),", ",str(stockthickness),", ",str(stocklength/2),", ", str(stockwidth/2),", 0.00)");
}
}
}
if (generategcode == true) {
owriteone("G90");
owriteone("G21");
// owriteone("(Move to safe Z to avoid workholding)");
// owriteone("G53G0Z-5.000");
}
//owritecomment("ENDSETUP");
}
\end{writecode}
\addtocounter{gcpscad}{93}
An example usage would be:
\begin{verbatim}
difference() {
setupstock(stocklength, stockwidth, stockthickness, zeroheight, stockorigin);
... // Cutting commands go here
}
\end{verbatim}
It will be necessary to have Python functions (\DescribeRoutine{xpos}, \DescribeRoutine{ypos},
and \DescribeRoutine{zpos}) which return the current values of the machine position in
Cartesian coordinates:
\lstset{firstnumber=\thegcpy}
\begin{writecode}{a}{gcodepreview.py}{python}
def xpos():
global mpx