Re: [CAD_CAM_EDM_DRO] Re: DXF bulge to I,J equations

>
> --- In CAD_CAM_EDM_DRO@y..., "jeffskey1" <jeffskey1@a...> wrote:
> > Does anyone know the equation's to convert a DXF arc that is
> > expressed with a "bulge" value to I and J values as used with G-
> code
> > G02 or G03? I am writing a software program to convert and optimize
> a
> > PROTEL pcb dxf file to cnc G-code for my maxnc mill.

Gee, this may be the hard way to do it. You don't mention which Protel
version you are using, but I think they all will generate Gerber and
Excellon files. These are BOTH variants of RS-274D, alias "G-code".

If the objects you are interested in are drawn on some layer of the
board with lines and arcs, it will come through in pretty much
standard form in the Gerber file. The Gerber has a few features
that work differently from standard machining codes. Since it is
designed for drawing with light, features don't have to be drawn
in any order, so you are not likely to get a continuous path.
It used D01, D02 and D03 to command "move to", "move to and
flash the light" and "draw to". I'm not sure I got those in the right
order. D10 and up specify the aperture that masks the light beam,
effectively a tool change. The variant of G-code suppresses the
decimal point, and also suppresses either leading or trailing zeros,
I always forget which. (It is leading on gerber and trailing on
Excellon, of vice versa!)

Are you doing this to cut the circuit patterns, or to route out the board,
or are you using it as a mechanical cad package?

Jon