Thread tightness using Part Design Hole on 0.20

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Sqeppy
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Thread tightness using Part Design Hole on 0.20

Post by Sqeppy »

I just installed FC 0.20 via chocolatey to have a play with the thread modelling and do some 3D printing of these threads. I made myself a little test case (see image) to print off which it did quite happily and gave me some threaded surfaces and countersinking that looked good. A quick check with some vernier calipers suggested that there was a very, very slight taper on the print but the external diameter was right.
testpiece.jpeg
testpiece.jpeg (36.73 KiB) Viewed 462 times
What I found though was that the printed threads were very tight against male threads that were nominally the same. There's a big list of things that could have gone wrong but I wanted to ask others doing the same thing for their experiences of printed threads via this route before I do anything more drastic. The threads are 3/8 UNF and M8 for full disclosure.
chrisb
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Re: Thread tightness using Part Design Hole on 0.20

Post by chrisb »

Printed - especially male - threads are almost always too small. I re-cut them with an appropriate taps and dies. How much off they are depends on the printer and heavily on the material. I had serious differences by using the same material just in another color. If you install addon Fasteners workbench, you see that there are some parameters which can be adjusted for printed threads.
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freedman
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Re: Thread tightness using Part Design Hole on 0.20

Post by freedman »

It's plane and simple, oozing plastic to create a female thread will probably make the hole too small. Get yourself a SLA or DLP and the threads will be almost perfect. I have seen some amazing thread work with DLP, things like 35mm camera lenses screwing right on.

I haven't looked lately but maybe the new slicers have software to target holes, they are almost always too small. That's a good thing if you want to run a Tap thru it.
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