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Getting the best out of OpenSCAD

calbryant.uk

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Re: Getting the best out of OpenSCAD

#41

Post by benhurmarcel »

bumbada wrote: post #38
laydn wrote: post #31

Do you know whether anyone using these types of tools (like OpenSCAD, CadQuery) in any serious design? By serious I mean, real, industrial use cases (think automotive, defense, aircraft, etc.). Or are these tools mainly targeting hobbyists?

We use those tools for industrial prototyping because we can program those in things like python. We use it for creating as crappy designs as fast as possible, not getting designers to premature optimization. For serious design no, we use expensive commercial software for that, once it is clear what the solution is. For exploring lots of different spaces cheap 3d printer, cheap CNC milling machines and laser cutters…

> We restrict access to serious software for early prototyping because people will try things like super complex organic shapes that require supports or special milling machines instead of machines that cost 100 less money.

Restricting access to CAD features is a perplexing way to compensate for lack of mechanical engineering skills.

Re: Getting the best out of OpenSCAD

#42

Post by hksh »

sysrpl wrote: post #36

I've worked a bit in OpenSCAD, and although I really enjoy the programming approach to generating 3D designs, it really is limited when compared to traditional CAD software. Being able to visually align an item, or use even basic commands like offset or fillet, are absent in OpenSCAD. Sure OpenSCAD has it's place, but I think that's in the area of procedural generated shapes, and it's not for 3D part or machine desig…

Try out fogleman/sdf[1]. It is like OpenSCAD in many ways but the distance field model gives you offsets and fillets more easily.

[1] https://github.com/fogleman/sdf

Re: Getting the best out of OpenSCAD

#43

Post by knolax »

Just tried OpenSCAD a couple days ago. The fact that intersection and difference operations often result in z-fighting is extremely frustrating. I read that that it was standard practice to manually account for this by "cutting more than you need". Such bandaid workarounds shouldn't need to exist. It's disappointing because conceptually OpenSCAD is very promising, but fundamental issues like this combined with the overly verbose syntax are holding it back.

Re: Getting the best out of OpenSCAD

#44

Post by Brian_K_White »

dbcurtis wrote: post #6
Sohcahtoa82 wrote: post #4

When I first got into 3D printing, I used OpenSCAD for my designs. The fact that objects are described with code made me feel right at home. It made it incredibly easy to make parametric designs. But later, I did start to feel the limitations. Not having automatic fillet/chamfer was huge. And sometimes, I wanted the ability to measure the distance between two points selected visually to make sure all my math involvin…

The trick with holes is to make your negative geometry penetrate past the surface. Meeting exactly on the surface will be too glitchey otherwise with the fast floating-point approximation. Fillets and chamfers though, yeah. The lack of those drives me away. As Quinn (Blondihacks) says: "Chamfers are what separate us from the animals.", and as This Old Tony says: "When it comes to chamfers, you don't want to cut corne…

All of my scad designs include an o=0.01; or 0.001, and all it's for is for prepending or appending to other values and expressions all over the place so that cuts and joins always overlap at least a little.

Re: Getting the best out of OpenSCAD

#45

Post by Brian_K_White »

sokoloff wrote: post #12
10000truths wrote: post #8

Earlier quoted context omitted.

Chamfers can be done by extruding the chamfer shape along a wireframe of the geometry to be chamfered, then subtracting the extrusion from the original geometry. I'm not sure how I'd do fillets in OpenSCAD, though.

You can use a Minkowski sum to give yourself a fillet. I did it once. It worked but was 2x as hard as learning enough Fusion360 to do that whole part and then each design after that is 20% as hard. I eventually got pretty good at OpenSCAD, but I’d say I now reach for OpenSCAD about 3x/year and everything else is in Fusion. I wish I’d have switched years ago.

I either live without, or get creative with use of hull, cylinder (including cones), making toroids by radial extruding circles (using the toroid as a cut shape just to get a fillet around a post), or I just open the scad file in freecad, and then apply the fillets in freecad.

It's definitely a weakness in the sales pitch having to work that hard for something you want that often.

Re: Getting the best out of OpenSCAD

#46

Post by dTal »

hksh wrote: post #42
sysrpl wrote: post #36

I've worked a bit in OpenSCAD, and although I really enjoy the programming approach to generating 3D designs, it really is limited when compared to traditional CAD software. Being able to visually align an item, or use even basic commands like offset or fillet, are absent in OpenSCAD. Sure OpenSCAD has it's place, but I think that's in the area of procedural generated shapes, and it's not for 3D part or machine desig…

Try out fogleman/sdf[1]. It is like OpenSCAD in many ways but the distance field model gives you offsets and fillets more easily. [1] https://github.com/fogleman/sdf

SDFs don't really work for CAD. You cannot even apply an anisotropic scale without making the distance field non-euclidian, which will render the effect of subsequent operations unintuitive. Extrusion along a path is impractical if not impossible in the general case.

Re: Getting the best out of OpenSCAD

#47

Post by dTal »

smrq wrote: post #21
dymk wrote: post #19

Earlier quoted context omitted.

Yes, CadQuery: https://cadquery.readthedocs.io/en/latest/intro.html Think OpenSCAD but based on a proper BREP kernel, so you can express something closer to actual curved surfaces instead of just rasterized approximations.

Something about CadQuery still feels a little off, but it's the only CAD tool I've found that really ticks all the boxes that I want, so I will nonetheless happily give it the prestigious "Least Bad According To Me" award.

I know what you mean. CadQuery's syntax is weird. Dot-chaining is a terrible interface for nesting commands. ZenCad is the most promising "OpenSCAD but with Python and BREP" project I've seen:

https://mirmik.github.io/zencad/en/index.html

Re: Getting the best out of OpenSCAD

#48

Post by Brian_K_White »

benhurmarcel wrote: post #41
bumbada wrote: post #38

Earlier quoted context omitted.

We use those tools for industrial prototyping because we can program those in things like python. We use it for creating as crappy designs as fast as possible, not getting designers to premature optimization. For serious design no, we use expensive commercial software for that, once it is clear what the solution is. For exploring lots of different spaces cheap 3d printer, cheap CNC milling machines and laser cutters…

> We restrict access to serious software for early prototyping because people will try things like super complex organic shapes that require supports or special milling machines instead of machines that cost 100 less money. Restricting access to CAD features is a perplexing way to compensate for lack of mechanical engineering skills.

I get it. I see no room to be perplexed since he explained it.

Aside from that, in general, requiring a student to do without a magic tool so they are forced to percieve and understand some fundamental that the magic tool hides, is hardly a new or perplexing concept. Otherwise, you get exactly what he just said, they got.

Re: Getting the best out of OpenSCAD

#49

Post by imglorp »

sysrpl wrote: post #36

I've worked a bit in OpenSCAD, and although I really enjoy the programming approach to generating 3D designs, it really is limited when compared to traditional CAD software. Being able to visually align an item, or use even basic commands like offset or fillet, are absent in OpenSCAD. Sure OpenSCAD has it's place, but I think that's in the area of procedural generated shapes, and it's not for 3D part or machine desig…

As a successful power user making physical objects, I'm wondering how you work without dimensioned drawings?

If you want to learn the distance between two arbitrary points on a part, you need to read the code, and sometimes even do some trig even if you wrote the code. Having markings on the axes is not the same thing: you really want to select two points on a drawing and say "show me this".

This is my biggest wish for OpenSCAD.

Re: Getting the best out of OpenSCAD

#50

Post by frafra »

ur-whale wrote: post #26
haberman wrote: post #22

I was under the impression that CadQuery sort of obsoletes OpenSCAD. CadQuery uses an more capable geometry kernel: https://github.com/CadQuery/cadquery

>I was under the impression that CadQuery sort of obsoletes OpenSCAD. I've started to switch to Cadquery from OpenSCAD because it lacks proper fillets and chamfers. I usually prefer the CSG (arithmetic tree of union/difference/intersection + transforms + base shape leaves) to model 3D objects, as opposed to Cadquery's "draw on 2D surfaces and extrude" approach, but OpenSCAD's lack of fillets / chamfers combined with…

The link to the GitHub issue is referring to the old archived repository. This should be the link to the most recent discussion: https://github.com/CadQuery/cadquery/issues/371
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