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OpenCAM

Notes, code, and discussion about opensource CAM software.

This started with a thread on cnczone: http://www.cnczone.com/forums/showthread.php?t=18861&page=1&pp=15

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Types of Programs

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CAD

CAD programs create geometry (points, curves, surfaces, solids, etc.)

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OpenSource CAD
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Commercial CAD
  • Autocad
  • Rhino
  • Multisurf
  • too many to list...
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CAD Theory/Algorithms
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CAM

CAM programs take geometry as input and create toolpaths(usually G-code).

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References

To search for papers, use scholar.google.com; then click the web search link to (try) to find the full text of the paper on-line. Also see http://www.inspire.net/otherstates.html for statewide virtual libraries

Call for action. Building CAD/CAM/CAE development resource index - http://opencascade.blogspot.com/2009/01/call-for-action-building-cadcamcae.html

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Toolpath Generation
  • Curvilinear Tool Paths for Pocket Machining, Michael Bieterman, Mathematics & Computing Technology, The Boeing Company, http://www.ima.umn.edu/industrial/2000-2001/bieterman/bieterman.pdf
  • Cutter path generation for 2.5D milling by combining multiple different cutter path patterns http://www.glue.umd.edu/~skgupta/Publication/IJPR04_Yao.pdf
  • A Classified Bibliography of Literature on NC Tool Path Generation Preprint version of article that appeared in Computer-Aided Design, Vol 29, No 3, March 1997. http://www.cgl.uwaterloo.ca/~smann/Papers/survey2.pdf
  • Algorithms for Real-Time Tool Path Generation http://www.bmf.hu/conferences/Neumann/Hermann.pdf
  • Toolpath generation along directions of maximum kinematic performance; a first cut at machine-optimal paths, Kim T.; Sarma S.E., Computer-Aided Design, Volume 34, Number 6, May 2002, pp. 453-468(16)
  • Curve fitting with arc splines for NC toolpath generation, Yeung, Millan K; Walton, Desmond J, Computer Aided Design. Vol. 26, no. 11, pp. 845-849. 1994
  • Robust Feedrate Selection for 3-Axis NC Machining Using Discrete Models, B. K. Fussell, R. B. Jerard, and J. G. Hemmett, Journal of Manufacturing Science and Engineering -- May 2001 -- Volume 123, Issue 2, pp. 214-224
  • Circular hole recognition for STL-based toolpath generation, Xiuzhi Qu, Brent Stucker, Rapid Prototyping Journal, 11/3 (2005)
  • Die and mold finishing--how fast?, Mason, F, Manufacturing Engineering (USA). Vol. 115, no. 3, pp. 35-36, 39-40, 42, 45, 47-48. Sept. 1995
  • Boundary-conformed toolpath generation for trimmed free-form surfaces via Coons reparametrization, Yang D.C.H.1; Chuang J.J.; Han Z.; Ding S., Journal of Materials Processing Technology, Volume 138, Number 1, 20 July 2003, pp. 138-144(7)
  • Guide curve based interpolation scheme of parametric curves for precision CNC machining, YUWEN SUN (1) ; JUN WANG (2) ; DONGMING GUO (1) ; , (Int. j. mach. tools manuf.) , 2006, vol. 46, no3-4, pp. 235-242 [8 page(s) (article)] (16 ref.)
  • Integrated Steepest-Directed and Iso-Cusped toolpath generation for three-axis CNC machining of sculptured parts, CHEN Z. C. (1) ; VICKERS G. W. (2) ; DONG Z. (2), (J. manuf. syst.) , 2003, vol. 22, no3, pp. 190-201 [12 page(s) (article)] (13 ref.)
  • Tool Path Generation for Freeform Surface Models, Elber, G. and Cohen, E., CAD, Vol. 26, pp. 490-496, June 1994, http://www.cs.utah.edu/gdc/publications/papers/elber94d.pdf
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Simulation/Backplot/Verify
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Misc
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Machine Controllers

Machine Controllers take G-code as input and control actual CNC machines

OpenSource Machine Control: 

   * EMC http://www.linuxcnc.org
   * AXIS, a Python GUI for EMC/EMC2, http://axis.unpy.net/index.cgi/
   * TurboCNC http://www.dakeng.com/turbo.html

Commercial Machine Control: 

   * Mach 3 http://www.machsupport.com/
   * Siemens
   * Fanuc
   * IBH Automation http://www.ibhautomation.com/
   * etc.
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Toolpath Output formats

G-Code: 

   * RS274, definition of G-code: http://www.isd.mel.nist.gov/documents/kramer/RS274NGC_1.pdf
   * RS274, version 2: http://www.isd.mel.nist.gov/documents/kramer/RS274NGC_22.pdf

HP/GL: 

   * ?

STEP-NC: 

   * An article on STEP-NC: http://www.manufacturingcenter.com/tooling/archives/1205/1205step_nc.asp

Something else 

   * ?
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Geometry Input formats

DXF (Autodesk Drawing eXchange Format): 

   * Definition by autodesk: http://www.autodesk.com/techpubs/autocad/acad2000/dxf/
   * http://www.autodesk.com/techpubs/autocad/acadr14/dxf/
   * From the Graphics File Formats FAQ: DXF is probably one of the most widely supported vector formats in the world today. DXF is rich in features, including: support for 3D objects, curves, text, associative dimensioning, and is an easy format to parse. The DXB format is a binary representation of a DXF file and they are usually smaller and faster to load than the equivalent DXF file.

   * SDXF, a Python library for writing DXF files http://dxf.stani.be/

IGES (=Initial Graphics Exchange Specification (?)): 

   * "IGES is a set of protocols for the transfer and display of graphical information on remote devices via a telephone or computer communications network. IGES does not define any new graphical file formats, but instead uses existing formats (such as CGM) to encapsulate graphical data.
   * IGES in the Graphics File Formats FAQ: http://www.faqs.org/faqs/graphics/fileformats-faq/part3/section-68.html
   * An article on IGES http://nvl.nist.gov/pub/nistpubs/sp958-lide/246-249.pdf

STL (Stereolithography Interface Format): 

   * Stl Format Description http://www.sdsc.edu/tmf/Stl-specs/stl.html
   * http://en.wikipedia.org/wiki/STL_%28file_format%29

STL to DXF conversion 

   * http://timeguy.com/cradek/stl-to-dxf

ISO 10303 "STEP" AP203 and AP214 

   * http://en.wikipedia.org/wiki/ISO_10303
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Open Source Code, libraries etc

   * VTK,The Visualization ToolKit, http://www.vtk.org/
   * OpenSceneGraph http://www.openscenegraph.org/
   * Coin3D a high-level 3D graphics toolkit for developing cross-platform real-time 3D visualization and visual simulation software. http://www.coin3d.org/
   * NIST Manufacturing Engineering Laboratory http://www.mel.nist.gov/product/software.htm
         o FBICS, Feature-Based Inspection/Control System - fbics_task (NC code gen) code is at fbicsTaskCc 
   * OpenCascade, http://www.opencascade.org/
         o OpenCascade Sketcher, simple use of OpenCascade libraries,http://www.laduga.ru/software/occsketcher/index.html
         o PythonCascade, python bindings to OpenCascade, http://www.pythonizer.org/pythoncascade/pythoncascade.html (Stale! not updated since 2003)
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Graphics / OpenGL

   * OpenGL tutorials http://nehe.gamedev.net/
   * Nate Robbins OpenGL tutorials http://www.xmission.com/~nate/tutors.html
   * NURBS and OpenGL http://www.mat.ucsb.edu/~c.ramakr/articles/dls/nurbs.pdf
   * http://www.geometrictools.com seems to contain a number of useful geometry algorithms
   * Building Block Software, The Boundary Offset Experts, http://www.buildingblock.com
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Python

   * Language: http://www.python.org/
   * GUI: http://wxpython.org
   * OpenGL: http://pyopengl.sourceforge.net/
   * BOA Constructor: http://boa-constructor.sourceforge.net/
   * Design Patterns in Python:
         o http://www.python.org/workshops/1997-10/proceedings/savikko.html
         o http://www.suttoncourtenay.org.uk/duncan/accu/pythonpatterns.html 
   * NURBS library for Python http://runten.tripod.com/NURBS/
   * NumPy examples http://www.scipy.org/Numpy_Example_List#head-801a34f50ffaa194c390aa6b0f5cc79a4551b0b9
   * Skencil, a vector drawing program written in Python http://www.skencil.org/index.html
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components

These components should be "plug-ins" i.e. it should be possbile to write more of them without modifying the rest of the architecture. 

  1. importers read geometry from file (which format?) and import to native geometry format (what?)
  2. exporters write native geometry to file in some format
  3. geometry creators/modifiers create or modify geometry
  4. toolpath generators given geometry, create toolpath.
  5. postprocessors given a toolpath, create output in some format


Low priority in the beginning... write native geometry to file in some format: 

   * an exporter should be able to read geometry

- DXF exists (pythoncad)

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exporters

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geometry creators/modifiers

geometry creators/modifiers: create/modify geometry 

   * a gcreator should be able to create geometry
         o point
               + abspoint 
         o curve
               + line
               + polyline
               + arc
               + Bezier, Spline 
         o surface 
   * a gmodifier should be able to modify/create/delete geometry
         o delete
         o translate
         o rotate
         o scale
         o mirror
         o copy
         o extrude? (+other surface generators)
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toolpath generators

toolpath generators: given geometry + tool(?), create toolpath. 

   * a toolpathgen should be able to read geometry
   * this is a form of geometry creator/modifier, i.e. a subclass of gcreator
   * Toolpath can output geometry (lines, curves, FEED/RAPID), canned cycles, M-codes, Toolchanges, coolant etc.
   * eventualy implement similar milling strategies to mastercam/surfcam
         o "1D" Drilling, Canned Drill Cycle, Peck Drill, Rigid Tap
               + for optimizing drill canned cycles: some solution to traveling salesman problem ? 
         o "2D" follow curve with cutter compensation, rough/finish modes?
         o "3D" Parallell, Radial, Flowline etc. rough/finish modes
         o "4D" etc. hard... :)
         o Simplifying toolpaths consisting of many short line segments can be done with the Douglas-Peucker algorithm. One implementation is found here http://cvs.linuxcnc.org/cvs/emc2/lib/python/rs274/author.py?rev=1.1 

   * some interesting notes on toolpath generation from http://www.freesteel.co.uk
         o Basic Cutter Location Studies http://www.freesteel.co.uk/wpblog/?p=59 details on how a cutter Z coordinate is located given (x,y), the cutter definition, and an STL surface. Interestingly the authors claim that most existing CAM software make little use of academic knowledge on the subject.
         o More machining questions http://www.freesteel.co.uk/wpblog/?p=63
         o Sample rate from machining tolerance http://www.freesteel.co.uk/wpblog/?p=64 how to calculate the sample rate for machining operations
         o The structure of a CAM system http://www.freesteel.co.uk/wpblog/?p=84 some useful notes on code reusability etc.
         o Automatic feature detection http://www.freesteel.co.uk/wpblog/?p=44
         o Intelligent machining algorithms http://www.freesteel.co.uk/wpblog/?p=43
         o Vertical Scallops http://www.freesteel.co.uk/wpblog/?p=31
         o http://www.freesteel.co.uk/wpblog/?p=29
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postprocessors

postprocessors: given a toolpath, create output 

   * a post should be able to read toolpaths 
   postp- a post processor for apt360 and more:  http://aptos.cvs.sourceforge.net/aptos/postp/

- i.e. map native toolpath to eg. G-codeThanks funny site

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