Re: [CAD_CAM_EDM_DRO]A question of size managenent.

--- In CAD_CAM_EDM_DRO@egroups.com, BillDarby <ddarby@s...> wrote:

> Hi Again Marcus
>
> Well,,,, I suspect that every owner of these Cad programs is faced

with this size problem and if their CNC will not handle an arc

> command they are simple forced to live with it. However my

controller is conversational and does utilize the arc command and

> would benefit from having a short conversion program that would

convert line segments of arcs into arc commands

Bill,

The Vector Arc-Spline will change faceted cross sections into arc-
splines. There is a tolerance so you can control how close it comes
to the actual positions defined by the lines. Vector is a little
limited in this respect in that it only handles 32000 entities max
per drawing object. You can place more than one object in a Vector
drawing, but if you try to process a million lines it is not too
practical.

I took the output from StlWork, which is a raster pattern surfacing
CAM program, opened a g-code file from it in Vector, backplotted it &
then Arc-Splined the individual passes. Vector has some slick
seletion and reversal of selection capabilities that let you select
around the edges, then reverse the selection to end up with just the
contours selected, and not the connections along the sides. Then it
will do Arc Splines in 3D normal planes(for all the passes at once),
automatically replacing all the splines with fitted arcs. I got
mixed results in that the reduction in entities varied from about 50%
to as little as 25% of the lines of code in the final program. You
have to be careful to remember to put the G18 & G19's in the file.
Vector can't automatically do that. It's also important that each
pass lie in a normal plane so the arcs can be cut. You can also
create offsets to comp for a different sized cutter radius. In
theory if you knew the size of the planned radius, you could create a
copy of the model as a toolpath. However any concave radii that were
less than the planned radius would be lost. That's life.

Best Regards,

Fred Smith
IMService