Fwd: Re: Is there an OpenSCAD dev who wants a CNC machine? (was Re: Managed to model a finger joint box with relieved fingers --- now how to actually cut it? Allow OpenSCAD to write out files?)

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Fwd: Re: Is there an OpenSCAD dev who wants a CNC machine? (was Re: Managed to model a finger joint box with relieved fingers --- now how to actually cut it? Allow OpenSCAD to write out files?)

mondo
In error, well it was quite late last night, I appear to have sent this
to jordan's personal email address, and not the list, so now you've all
got it too.




Hi Jordan,

On 16/08/2020 01:48, Jordan Brown wrote:
> I'd like to figure out how to drive my CNC machine from an OpenSCAD
> model... so far, I'm not seeing how, other than some tool chains that
> seem fragile, unpleasant, or both.

The cad/cam software i use, and have supplied to others, is deskcnc. It
can handle dxf, stl, hpgl, point cloud, gerber and image files. So it
will produce g-code, and machine some of the file formats exported by
openscad. If you want to use free software, then.Desk Proto will accept
stl files and image files and produce useable g-code. If you need to
generate g-code directly from openscad, (or any cad program), then once
you've generated the shape, then you need to generate the tool paths. It
is much easier to generate gcode for 3d printing, then it is for
machining, working from cad, although if you wanted your machining to be
slow, and only having, say 0.4mm depth of cut with a half mm diameter
end mill, then machining would be very similar, and that is basically
what happens when machining from stl. From dxf files, you select areas
to pocket, or profile, (often referred to as 'two and a half D') and
that can proceed at a faster rate since step overs are larger. It is
very easy to design shapes that can not be machined, much harder to
design shapes that can not be 3d printed.

If you want to drive your mill direct from openscad, say, in a similar
manner as octoprint/pi, curio, and other slicing programs drive 3d
printers, then that is most likely never going to happen.

I've referred before to the mvc paradigm I do not see openscad as the
model, but a view of the model. Gcode is another view. Using openscad to
produce the model, one that can be translated into other views, is not
straightforward, and most likely is not the best way of getting where
you want to be, but If you only have a hammer, then most things have to
become nails.

Suppose you start with something simple, a cube, say. If you could
export the coordinates of the four top corners, then you need to be
aware of the size and shape of the stock material you're cutting the
cube from, the size of the tool, the tool profile, number of flutes,
speeds, feeds, if coolant is needed, what type, material of cutter,
material of stock, work holding method. Then, you can calculate the tool
paths, bearing in mind chip removal, climb or normal or adaptive tool
paths, whatever, and stuff i've not mentioned. For plastic filament 3d
printing, once you've decided the material, the slicer takes care of it.
Even if you by-pass the slicer stage, and write the raw g-code, it is
very consistent, with few variables.

It is all very interesting.


Best wishes,

Ray



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