Re: [CAD_CAM_EDM_DRO] Re: How to Program a CAD / G-code/Machine commands freesource code?

> Q1: in simple terms does the current nurbs is the best method to draw
> a surface for use in CAD and to be translated to CAM then actual CNC
> if the answer is yes:
> what is the data structure to use. nurbs is complex and also is
> simple and lot of code books available to put something.
> to do a single nurb curve is a ok
> next how to make a surface out of that.
> for a surface i am sure we can find a book showing how make a surface

If you want to machine _one_ nurbs surface then you can maybe calculate
the offset surface of it analytically and get the toolpaths from that.

As soon as you have _many_ surfaces or holes or anything more complex
the analytic approach gets nontrivial (that code-speak for "really hard").

Most CAM programs get around this by triangulating the model at some
finite resolution (that can be 0.01mm for example) and calculating the
toolpaths from that. Finding toolpaths from a triangulated model is a
bit easier and more robust (less risk for under/over-cuts).

I've experimented a bit in C# with a "drop-cutter" algorithm for surface
finishing of triangulated surfaces. See here:
http://www.anderswallin.net/2007/08/drop-cutter-in-c-v2/

the code is here:
http://code.google.com/p/monocam/

I don't have too much time for this project so it would be nice if other
people were interested and helped out.

regards,

Anders