threads

doug_hills

can anyone direct me to the learning material on how to draft threads?  I want to create a thread with a round peak and valley. so when the axis is vertical the thread lines are closer to vertical than horizontal, allowing me to 3D print it in plastic, without support.

SethF

As always, there are a hundred ways to skin a CAD.

In this discussion someone points out a feature script for making threads, but depending on what you're doing, likely overkill:
https://forum.onshape.com/discussion/6476/threaded-hole-part-tool

Here, @Evan_Reese says that an equilateral triangle section prints well for him:
https://forum.onshape.com/discussion/21473/optimized-thread-form-for-3d-printing-featurscript

I admit that I have not yet printed any threads, so I don't actually have parameters to suggest (which would obviously vary widely with your actual printer), but if it were me, I'd probably just for the fun of it start with something like this and mess with the parameters until I got something that worked well for my printer/use case: https://cad.onshape.com/documents/a9cd2a06c0af2da77724e251/v/8c454b7c5e9122ba91e3b66b/e/a2b5865d5e7184cafaeb1758

EvanReese

If I understand your goal, you want threads that have round cross sections like this? Here's one way: https://cad.onshape.com/documents/8e7adc386aac2c47ef7cdf52/w/27978ad3d4fc4dfe7c19ae45/e/33e62128efe6d93a79062e9c

doug_hills

thank you, the round cross-section allows the surfaces to remain close to vertical. this means that the layers of thread won't need "support" in the printer. I'm just experimenting at this point,

EvanReese

As Seth said, I've personally had plenty of success just using standard 60° triangular section threads (assuming the thread axis is aligned with Z). This exceeds the standard 45° overhang rule of thumb, but I think it works because of the way each layer stacks on the last one. If you slice it and scrub through layer by layer, you'll see that the new layer has very little overhang from the last one. This is for FDM. I've even had luck printing down to M2 on a resin printer this way.