[OpenSCAD] DXF for cut and engrave

nop head nop.head at gmail.com
Thu Oct 24 07:33:39 EDT 2019


Yes but laser drivers don't offset the cut by half the kerf and they don't
accept a 3D model that represents a surface with engraving as trenches
equal to the kerf and so derive a tool path running down the centre. A CAM
tool to drive a mill accepts a model of the intended result, not a tool
path. Laser artwork is just the tool path in different colours not a model
of the desired end result. OpenSCAD can produce a perfectly good model of
the end result. It can't produce tool paths.

On Thu, 24 Oct 2019 at 11:50, Rogier Wolff <R.E.Wolff at bitwizard.nl> wrote:

> On Thu, Oct 24, 2019 at 10:56:15AM +0100, nop head wrote:
> > The problem is a laser doesn't cut a line with zero thickness but people
> > pretend it does.
> >
> > You can model any object a laser can produce in OpenSCAD. What is needed
> is
> > a CAM stage for lasers that creates the tool path, just as 3D printing
> and
> > milling. For some reason the CAM stage is ignored when laser cutting.
>
> The CAM stage traditionally happens in the printer driver under
> windows. A program, ANY program tells windows it wants to print
> something. Then together with some confguration, the printer driver
> translates e.g. the color of the line into different commands for the
> laser (say: red: "all the way through at 100% laser power and 10%
> speed, blue: "just a scorched line at 50% laser power and 100%
> speed", green: "engraved in bitmap mode").
>
> The problem is that with those things tightly coupled to the laser
> device in question, and them being closed source, it is difficult to
> optimize those things. For example, at my friends' the laser will
> easily cut up a single "rounded box" outline into 4 lines and for
> quarter-circles and do them in the woarst possible order you can
> imagine.
>
> Optimizing the toolpath is equivalent to the travelling salesman
> problem and therefore NP complete. But that doesn't mean you can't do
> a meaningful optimization. An easy optimization (that 3D printer
> slicers should also do!) would be to always pick the closest
> linesegment. In the rounded-box example that immediately leads to the
> optimal solution. Then as a post processing step, investigate the
> longest non-cutting moves and see if you can improve on them. Take a
> segment between two long-moves and try to insert it in the path
> somewhere to see if the total non-cutting path length can be reduced.
>
> Sorry for my rant.
>
>         Roger.
>
>
>
> >
> > On Thu, 24 Oct 2019 at 09:39, Troberg <troberg.anders at gmail.com> wrote:
> >
> > > OpenSCAD mailing list wrote
> > > > On Tue, Oct 22, 2019 at 11:10:03AM -0700, WillAdams via Discuss
> wrote:
> > > >>I have probably missed part of this discussion, but for me: I use
> > > > openscad to design a box for a project in 3D and then I lay the
> pieces
> > > > flat and send the outline to be laser-cut.
> > >
> > > OpenSCAD is heavily oriented towards 3D-printing, and, to some extent,
> > > leaves us laser cutter guys out in the cold, or at least requiring us
> to
> > > make irritating workarounds.
> > >
> > > For example, a line is useless in 3D-printing, but extremely useful in
> > > laser
> > > cutting (google "living hinge" for a good example).
> > >
> > > I really hope that considerations for laser cuttings will enter into
> the
> > > plan for OpenSCAD, it would mean a lot to us. 3D-printing is just too
> slow,
> > > has too small work area and too limited in materials available to be
> useful
> > > for me.
> > >
> > >
> > >
> > > --
> > > Sent from: http://forum.openscad.org/
> > >
> > > _______________________________________________
> > > OpenSCAD mailing list
> > > Discuss at lists.openscad.org
> > > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
> > >
>
> > _______________________________________________
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>
>
> --
> ** R.E.Wolff at BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110
> **
> **    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233    **
> The plan was simple, like my brother-in-law Phil. But unlike
> Phil, this plan just might work.
>
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