Screw thread not working

[3D_Ken]

The attached design is supposed to produce an object that will screw into a standard 5/8 x 24 tpi UNEF fitting.  It the resulting print will not screw into the fitting.  I don't know if the diameter is too big or the threads are spaced wrong, but I have tried several fittings and can't get my print to screw in.

Please tell me what I'm doing wrong.

Ken

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[TheCADWhisperer · Accepted solution]

You did not have any lead-out on the thread.

Chamfer feature AFTER the thread in Fusion (that's just the way it is).

You might also consider that 3D printing is not a particularly precise process.

You might want to PressPull the face of the thread to give a bit more clearance.

[etfrench]

1. Un-modeled thread
2. Chamfer
3. Model thread

p.s. Model in this scenario is a setting in the thread dialogue.

[3D_Ken]

Thanks to both of you.  I now have a perfect print.  Never in a million years would I have ever figured this out on my own.

[TheCADWhisperer]

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@3D_Ken wrote:

Thanks to both of you.  I now have a perfect print.  Never in a million years would I have ever figured this out on my own.

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I've probably cut tens of thousands of threads out on the shop floor.

I recognized the issue at first glance - years ago.

It is a commonly missed issue here on the forums.

Makes me wonder how many people never come here to the forums and somehow force a mating fastener till it takes up the modeled threads.  Hopefully not pulling apart their print layers in the process.

[3D_Ken]

Sorry to bother you again, but I have spent over an hour trying to get a female thread to work.  Nothing I did worked.  I'm attaching my base setup so you can see what I started with.

Thanks again, Ken

[TheCADWhisperer]

Leave the thread as cosmetic.

Add the Chamfer.

Edit Feature of the Hole and now set the thread to Modeled.

[3D_Ken]

I thought I had tried this already, but just to make sure, I tried your file and it still fails.  I have several different fittings I have tried to screw in.  Depending on which fitting I try, it will screw in between 1/4 turn and 1 full turn before it will not screw in any more.  I'm questioning if this is a lead in problem or something else.

Thanks for your help, Ken

[etfrench]

Have you tried this?

[TheCADWhisperer · Accepted solution]

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@3D_Ken wrote:

I'm questioning if this is a lead in problem or something else.

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I thought I already mentioned in my original post that 3D printing is not very precise.

Even on my $60,000 printers I allow for a bit of extra clearance for threads.

[3D_Ken]

Yes you were right about the preciseness.  I got over confident because the first piece (male thread) screwed on so well.  I guess it was off in a good direction.

The solution was to increase the X and Y dimensions of the entire object to 101%.  Now it works well.  I guess it would be a bit more perfect at 100.09% or 100.085%, but that level of exactness is not required.

It would be nice if Fusion would allow some tuning when specifying a thread size or allow you to create your own thread from a few parameters.  I know I could construct a thread from scratch, but that would be too much work for me.

If I was unable to resize the entire object (as I did), my guess is that I would construct a cutting tool, resize it, and cut out the thread hole.

Thanks again for all your help.  I really learned a lot about 3-D printing of threads.