Re: [CAD_CAM_EDM_DRO]A question of size managenent.

Hi Marcus

Marcus & Eva wrote:

> Hi Bill:
> How did the program get to having the arcs broken up into line segments
> in the first place?
> Was the toolpath generated from a spline or a surface in the CAM software?

I used Aus Cad to generate the tool path. Specifically their "mouldmaker" feature called "swept surface". I think it is about
identical to Bob Cad. Not a sophisticated looking as my version 16 but seems to be more functional. (You have to sell your soul to
trim the un wanted portion of a circle in either.)

>
> Splines and arcs will output as line segments in most CAM software, since
> there are very few machine controls out there that can handle NURBS input.
> (Splines and surfaces are often described mathematically as NURBS entities).
> Sometimes, it's difficult to determine if the entity you see on the screen
> is an arc or a spline.

Yes, I can see where almost anything would have some difficulty discerning if a line segment is a line segment with no relationship
to others or part of a group of line segments forming an arc. I would think though, that it would be possible to write an algorithm
which looks at each segment and compares it to the previous two segments to see if they conform to the geometry of an arc. But. Is
there such a program??

>
> Most programs have some king of "analyze" function that will tell you.
>
> Anyway, back to your original question.
> A lot of the guys I worked with, preferred to take a simple 2D profile and
> program only the first pass.

Not sure what you are saying here. (don't follow,,,, thick maybe) <VBG>

>
> They would then "loop" the program to create all the subsequent passes.
> That gave them only one short chunk of code to edit.
> If you have multiple copies of your profile to cut, it makes for a very
> economical program, but you have to know how to set up the loop commands in
> your particular controller.
> Hope this helps

The code I am referring to is for contouring a single part and I think you talking about looping or calling a sub(s) to do
repetitive work.

Thanks Marcus
Bill D

>
>
> Marcus
> -----Original Message-----
> From: BillDarby <ddarby@...>
> To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
> Date: Wednesday, November 29, 2000 7:38 AM
> Subject: Re: [CAD_CAM_EDM_DRO]A question of size managenent.
>
> >Hi All
> >
> > I recently ran a tool path with 36,000 lines of code. (no big deal
> in the real world) Now my question is this: This
> >path was really only 200 sets of (a line an arc and a second line) or
> [line, arc, line, 200 times]. "If" I could have entered the
> >summation of the 160 lines of code representing each arc into one common
> "arc command" I would have had a total of just 600 lines
> >of code.
> >
> > As it was, there was not enough memory to edit on the CNC. It
> could run the program, but if I wanted to change anything I
> >had to do the change on my off line program on my PC, then reload by floppy
> to the CNC.
> >
> > Is there any software that could convert all these line commands
> into arc commands?
> >
> >Just compelled to ask!!!
> >
> >Bill Darby
> >
> >Also (have never seen my CNC do this before) As these [160 line] arcs
> became smaller my CNC began what appeared like a series of
> >jerky motions as it rounded these corners and sped up when it hit the
> straight-away. The cut looked and felt perfect but there
> >definitely some jerking going on as the entire mill set up a rocking motion
> on the wooden floor. I almost thought the CPU was
> >bogged down. The feed was set at 32 IPM and dropped to less then 1/3 rd on
> the corners.
> >
> >What do you think is going on??
> >
> >
> >
>
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