[OpenSCAD] DXF for cut and engrave

Rob Ward rl.ward at bigpond.com
Sat Oct 26 03:26:01 EDT 2019


Thanks nop head, I have looked it up and tried it. It has been a 
blind-spot of mine.

projection() will be useful, especially for the printing of templates 
for various sections to try for a fit.

However the  resulting drawing is one plane (cross section or profile at 
one depth), rather than an elevation (the complete model as viewed from 
the side or from the top) and also has to be rendered by F6 before the 
projection() which eliminates any colour information.

I am not up with the technicalities of how OpenSCAD differs in preview 
(F5) as opposed to render (F6), but it would be more useful, I think, if 
the projection() worked on the preview stage and collapsed coloured 
sides on to a profile as an elevation. It would also be handy to be able 
to define a vector space to crop how much of the model is depicted. I am 
wondering if this would allow new tool path designers (like Cura for 
STL->GCODE) to be developed for OpenSCAD-> SVG -> GCode.

I suspect what I am wishing for is probably not technically trivial and 
maybe not worth the effort. Comments? Explanations?

RobW


On 25/10/19 8:24 am, nop head wrote:
> You can project 3D shapes onto a 2D plane and export them as SVG or 
> DXF files using projection().
>
> On Thu, 24 Oct 2019 at 22:20, Rob Ward <rl.ward at bigpond.com 
> <mailto:rl.ward at bigpond.com>> wrote:
>
>     One of my requests from a while ago was to be able to "draw" or
>     render an elevation (or designated plane) of a 3-D model into a
>     2-D line art (SVG?). I could use this in two practical ways. First
>     for documentation purposes, and secondly to be able to print
>     "proof of fit" paper shapes to quickly check if things work.
>
>     A third way this thread reveals (unfortunately I don't own a
>     laser) is CAM packages could be developed from this format to
>     control various forms of cutting tools. Just like there are many
>     STL to Gcode "slicers" around to choose from, a similar ecosystem
>     could spring from this feature in OpenSCAD.
>
>     Whether an edge is considered a line around a shape or how a
>     colour is interpreted, layers etc etc is left up to the CAM
>     interpreter, of which there could be many flavours. However at
>     least a standardized OpenSCAD approach to a 2-D rendering system
>     would be a major step in focussing efforts to progress in this area.
>
>     Just viewing this discussion as a very basic, but most
>     appreciative, OpenSCAD User.
>
>     Cheers, RobW
>
>     On 25 October 2019 1:37:03 am AEDT, Torsten Paul
>     <Torsten.Paul at gmx.de <mailto:Torsten.Paul at gmx.de>> wrote:
>
>         On 24.10.19 15:22, Troberg wrote:
>
>             OpenSCAD does 2D fairly good, so usually it works out, but
>             there are two missing primitives which would help a lot:
>             line and point. 
>
>
>         That question does come up now and again, but nobody
>         really took the plunge to design something that fits
>         into OpenSCAD.
>
>         It's not as simple as just adding line() as that
>         would break some of the current assumptions. However
>         I believe having a state with unclosed polygons is
>         not a problem in general as for example this happens
>         inside of text() too.
>
>         Just to highlight what I mean, here's some dummy code
>         that could model something resembling the letter L
>
>         p = [
>            [36,-5],[12,-5],[12,-48)],[6,-48],[6, 0],[36, 0]
>         ];
>
>         polygon() {
>            point(p[0]);
>            for (a = [1:len(p)])
>              line(p[a - 1], p[a]);
>         }
>
>         Now that looks not very impressive as this would
>         work with just polygon(p) too, but text() also uses
>         quadratic and cubic splines. At that point it gets
>         much more interesting I think.
>
>         In the example above, the polygon() would also mean
>         that at this point the polygon is closed and could
>         be extruded to 3D. Without that guaranty it would be
>         still exportable to DXF or SVG.
>
>         ciao,
>            Torsten.
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-- 

*Rob Ward*
Lake Tyers Beach, 3909
Lake Tyers Beach Website <http://www.laketyersbeach.net.au>
Ubuntu Mate - A great OS <https://ubuntu-mate.org/>

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