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Comment by Filligree | Hacker News Reader

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Filligree·

How would you design a screw thread adapter that needs to resist shear?

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I certainly wouldn't 3d print it, that is a job for off the shelf metal part.

Nobody has any clue what the thing is. :D

It claims to be BSP, but it’s 1 inch (1.1?) with 19 threads per inch (18?), which matches no standard I’ve ever found.

If it needs any amount of strength you'll want to find someone with a lathe. BSP tells me it may be tapered(?) so find someone with a taper attachment. Even as a hobbyist I could probably make one of those on my lathe faster than drawing it and printing it on my 3d printer.

Print a mold, cast it in wax, put that in casting sand, then do a lost-wax casting in aluminum or something more exotic if necessary and you're able?

I think at that point I'd have to ask someone to make it for me.

Lathe would be the tool to use in that case.

You're absolutely right. But I have a 3D printer, casting sand, and a torch... I don't have a lathe, sadly.

A 3D printed plastic part could be fine depending on the application. Certainly worth considering/testing. Printing it flat on the bed (with a small flat side) so layers are lengthwise may work.

See also threaded inserts for the other half of that fastener.

At some point you have so many competing compromises that you're sacrificing one aspect to improve another. When this happens, I pick what's easiest to print and make up the strength with a lot of extra wall loops, slightly higher print temperature (for better layer adhesion, as print quality allows), and stronger material selection.

If this is a critical or load bearing part, I'd skip 3D printing entirely and get it machined.

45 degrees to the bed, 3+ walls, gyroid infill 40%

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