Help with Thread Clearance for 3D Printing

[jalvarezrecino]

Hi everyone,

I am working on a 3D printed assembly that involves two threaded parts, which I've designed in Fusion 360 (see attached .f3d file).

I am trying to ensure that these parts actually screw together smoothly once they are manufactured. Currently, I have Modeled threads using an ANSI Unified profile with a Class 3A fit.

While my interference check shows "No Interference," I am concerned that this "line-to-line" contact won't allow for the tolerances required by a 3D printer.

My questions are:

1. Should I change the Thread Class from 3A to a looser standard like 2A/2B to provide more natural clearance?

2. Is it standard practice to manually use the Press/Pull tool on the thread faces to create a physical gap? If so, what is a typical offset value that works well for printed threads?

3. Looking at the cross-section of my model, are there any geometry issues (like sharp peaks or valleys) that might make the assembly seize?

I've attached the Fusion 360 archive file. I'd appreciate any advice on how to make these threads functional!

[g-andresen]

Hi,

take a look at this thread by @MRWakefield 

günther

[bbtfabrications]

Personally I've had good luck using a large existing thread with modeled checked.  Then I use the press pull command to offset the thread angle faces by -.005-.01 to increase the clearance.  It's kind of trial and error but it's worked for me several times.