I'm looking at a CSG to STEP convertor[1] and ask: why not make @OpenSCAD export STEP? No need for any extra libraries, hopefully. Also, one fewer step for impedance matching. All you need is to generate hulls and minks automatically, using primitives available in STEP. Surely someone has done that before, right? Github is vast, it must be in there somewhere.
@pro@OpenSCAD Saw your post https://zaitcev.livejournal.com/266803.html and got back here — do you know that FreeCAD can render OpenSCAD and exports STEP? It uses OpenSCAD to more or less compile to CSG and then renders CSG.
Not suggesting that you shouldn't add STEP to OpenSCAD! ☺
@mcdanlj@OpenSCAD Someone still reads LiveJournal? That's pretty amazing.
In a sane world, I should just use FreeCAD. All I want is to take a chunk of bar stock, make clean parallel surfaces, and mill 3 90-degree V-notches across. I can do it on a manual mill in less than an hour. The whole project was supposed to be about learning to send jobs to CNC subcontractors.
But I found FreeCAD so hard to use that it literally may be easier to make OpenSCAD export a nicely constructive STEP that a CNC contractor can use.
I suppose I can make a bar with notches in FreeCAD if I try hard enough. Should take a couple of days perhaps. But I cannot imagine it working while going forward. It's just not getting any easier with practice: it's all the clicking and entering into boxes, and switching the benches.
Fedora dropping FreeCAD was the last nail in that coffin.
I feel moderately fluent in FreeCAD by now, and what you describe seems very simple and quick to me; would be a bit faster for me in FreeCAD than in OpenSCAD. But not trying to talk you into a switch, and direct STEP output from OpenSCAD seems like an awesome addition.
Extrude a bar, pocket a V-notch, multi-transform to make a linear copy and then mirror it. (There are other ways depending on how it's intended to be arranged, I imagined it centered.) Took less time to model than to write the this description of how I did it... ☺
@mcdanlj@OpenSCAD Your model is pretty much what I had in mind, although I forgot to mention that I need notches of different sizes (they are bending dies for varying thicknesses, intended to go into my arbor press).
I'm going to continue tinkering with STEP though, because I'm curious as to how all this works.
@pro@OpenSCAD Ah, that would have been even simpler in the design tree, just putting the three notches into a single sketch to pocket, and dropping the multi-transform, which was there just as an example for modeling with less drawing in a sketch.
I'm curious about a few things...
Are you assuming mm as the base unit when writing a STEP (current typical practice in OpenSCAD AFAIK) or are you including some way of explicitly defining the base unit?
Are you preserving color and representing it in the STEP?
When (on livejournal) you say "possibly square or round" do you mean you are representing a rectangular face as a single square instead of as two triangles as it would be in an STL, and stitching curves back together at some epsilon (like the "arc welder" plugin for 3d printing slicers)?
mm (but I know that all websites ask, so maybe TBD and some metadata if possible. I'm yet to read the standard for the CT primitive.)
just ignoring color for now.
I mean that flat faces can be represented using one plane and a bunch of lines. The round is only for what's actually curved in OpenSCAD language.
BTW, I never was able to import an STL into FreeCAD successfully. Firstly, the import process cannot figure out inside and outside correctly. And "repair" step either does nothing or makes it worse. Secondly, I cannot do anything with the result. Yes it sits in the tree and UI kinda displays it in 3D, but nothing else is possible. It all goes back to my fundamental inability to make FreeCAD do anything, I'm sure.
@pro I definitely have run into plenty of models that have to be scaled by 24.5x to make sense, and a few 10x, but fortunately, mm seems to have mostly won by now.
I've definitely worked successfully on STLs in FreeCAD, and I'm happy to share more, but not trying to talk you into it. ☺ So let me know if you want me to share more. Otherwise I'll just celebrate the idea of STEP export from OpenSCAD. 😀
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