topic Threads that work in Fusion Design, Validate & Document Forum

Threads that work

SimonPlatten — Thu, 04 May 2023 05:37:10 GMT

I've created a container using a cylinder with a thread on it, from the container with modelled thread I created a cap by creating another cylinder that goes on the end and subtracted the body of the first cylinder from the cap, keeping the object I am subtracting.

I then 3D printed both parts, however they do not screw together fully. Have I done something wrong ?

I would share the model, however I'm not sure how to ?

[Edit]. With filing I've managed to get both parts to screw together.

Re: Threads that work

etfrench — Thu, 04 May 2023 06:35:34 GMT

Yes, you are doing it wrong😁 (fdm)3d printers usually don't print threads to their defined tolerances. Offsetting the thread faces by a small amount will make them fit together better. Fusion 360 also doesn't create the proper chamfer on the end of a thread. You cannot add the chamfer before making the thread and the thread cannot be Modeled before adding the chamfer. Create the thread with Modeled unchecked, create the chamfer, then edit the thread to Modeled.

Re: Threads that work

SimonPlatten — Thu, 04 May 2023 06:37:38 GMT

Thank you, certainly worth a go...is there any tutorial or video on how to do this, I've filed the prints and now they screw together much better than before.

Re: Threads that work

etfrench — Thu, 04 May 2023 06:50:09 GMT

Just select each face on the thread (there are four) and use the Offset Face command. Chamfer technique is in my first post.

Re: Threads that work

SimonPlatten — Thu, 04 May 2023 06:51:34 GMT

Ok, is there any guide on the chamfer size to use according to the thread size ?

Re: Threads that work

etfrench — Thu, 04 May 2023 06:56:18 GMT

Start with the difference between the major and minor diameters, but a little more won't hurt.

Re: Threads that work

MRWakefield — Thu, 04 May 2023 09:23:28 GMT

Just a little heads-up... You're better off selecting just three of the faces for offsetting: crest, root and one flank. If you select crest, root and both flanks you'll find that the thread form becomes distorted. The crest flat will get narrower and the root flat will get wider. Obviously the more you offset, the greater the distortion.

Re: Threads that work

g-andresen — Thu, 04 May 2023 10:03:03 GMT

Hi,

This is the way for chamfer and thread offset.
You have to determine the value for the offset in trials.
I've had good experience with an offset of -0.1mm for PLA/PETG/ASA for M20.

(view in My Videos)

günther

Re: Threads that work

SimonPlatten — Thu, 04 May 2023 11:30:42 GMT

Thank you