Re: [CAD_CAM_EDM_DRO] Traveling Salesman Syndrome

Hi Bob, Jon,

PLT format? I have found that ViewCompanion v2.0 is inexpensive and can
convert .PLT files to DXF or a host of other formats. From there, you
could import into Vector CAD/CAM; reorganize, and generate the Gcode.
OR the CAD-only could save DXF, and let Yeager's ACE generate the
Gcode. The Harley file is a good file to experiment on (who can read
DXF's), as I have found out.

I haven't designed any boards in Eagle (yet), but I have exported the
hexapod and other demos for experimentation/edification.

http://www.softwarecompanions.com/ (ViewCompanion)

I'll experiment with the .PLT file output!

Jon had some good comments on the T.S. problem. Seems to me, that as
the "traces" are "closed" tool paths, when you cut them, you come back
to the same point. So like Jon said, we're only needing to sort the
rapids, I.E., the starting points of the traces, as I see it. How about
a "flood fill" to keep the rapids in-between trace starts to a minimum?
Start at origin, find the first point from that within a specified
radius, cut it, find the remainder of start points, then expand the
radius, etc. Or maybe the center of the radius needs to be moved to the
point just done? (that's not really a flood).

Alan KM6VV


cncdxf@... wrote:

>
> Hi,
> The Traveling Salesman Syndrome (TSS) can be advoided
> by planing ones GCode from the beginning. Since we know
> a DXF drawing will convert into GCode the same way it
> is was drawn, is the first step.
> I mentioned the HARLEY file because it was avalable
> as a DXF to everyone in the group. Having a drawing to
> refer to as an example has really helped. The HARLEY file
> can be easily and cheaply fixed. Pull it into a Cad or
> Corel program. Trace it as an other LEVEL and save that DXF.
> I suggest tracing the cuts in a circular pattern. Redraw the
> outer cuts moving inwards. You could also cut from right
> to left.
> I mill circuit boards for local Engineers and
> students. My machine is very slow. After laying out
> a large circuit board using Eagle, I was shocked to see
> the Traveling Salesman Syndrome strike big time. The
> last few days I have been playing with saving the Eagle
> layout outline in PLT format. Then I convert the PLT
> to DXF. I then retrace the PLT file with a different layer
> in Turbocad. I save the new layer as the new DXF. When it
> is converted to GCode, it purrs.
> What bugs me at this point is how Corel makes some
> of the lines in a DXF fatter. I feel spending more money
> for yet an other program to fix TSS is uncalled for!
> Like I said before, I brought up this subject because
> I thought I was doing something wrong. I say what good is
> a fast machine if you are running a slow GCode. Please
> keep thread title as Traveling Salesman Syndrome, this will
> help future travelers when the search the archives.
>
> Bob
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > rab@r... wrote:
> >
> > > Don't suppose anyone can recommend a good algorithm for solving
> the
> > > Traveling Salesman problem ?
> >
> > There may not be any. Now, for machining, things are different,
> because
> > any cutting motion is good. What you try to minimize is the non-
> cutting
> > movements. This makes the problem much easier. Also, the case
> where
> > there are hundreds or thousands of cutting movements, usually with
> exactly
> > one non-cutting movement between them, is a lot simpler problem.
> > You throw away all non-cutting movements, just keeping the cutting
> > movement strings as they were. Now, you pick one at random, do it,
> > mark it done and then search the endpoints of all other strings to
> see
> > which one is closest. When there are no more uncompleted movements
> > left, you're done. this is a very simple scheme, but it usually
> reduces
> > badly
> > planned toolpaths by up to 90% (Those would have to be REALLY bad,
> > but I've seen them.) Depending on how the toolpath is written,
> detecting
> > cutting from non-cutting movements may or may not be easy.
> >
> > Jon