Re: Traveling Salesman Syndrome

Hi Doug,
I think I remember finding a PLT optimizer at

http://www.geocities.com/SiliconValley/Lab/3685/plotter/plotter.htm

But I had no luck getting it to run. Someone asked me to
engrave a picture of a dog on a wooden box. I used the free version
of WINTOPO to make a DXF from a BMP file. Lots of traveling on
that one! It had its ups and downs also. So many in fact I thought
I was watching a sewing machine.

Bob

--- In CAD_CAM_EDM_DRO@y..., dougrasmussen@c... wrote:
> Bob,
>
> I used to see fairly inexpensive pen plotter optimization software
> which aimed at solving the same problem encountered in milling. I
> don't know if the software actually changed the original dxf file
or
> produced a temporary optimized hpgl file which was plotted
> immediately. I suspect the latter. If so, maybe the hpgl could be
> intercepted and converted to gcode.
>
> interesting topic,
>
> Doug
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., cncdxf@a... 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