Parametric question: can a screw thread be parametricized?

[agordon]

I feel badly for asking yet another question ... hoping the welcome mat isn't wearing out soon!

I have successfully created a BA standard full nut using parametrics based on hole that matches the thread OD, so I can quickly create nuts of varying size for my 3D model loco (McMaster-Carr doesn't carry BA threaded items).

Can I parametricize the thread?  If I change the parametric data for diameter to another BA size, the thread remains as selected even though the body is now a very different size: easy to fix by editing the thread and setting it to the correct dia in the thread selection menu, but it would  be really neat if the thread data could be a parameter.

I have attached the screenshot of the parameter settings used so far ...

Thanks in advance for any suggestions!  Tony

[kate.raskauskas · Accepted solution]

Hi @agordon,

That's what the forum is for! 

The thread function itself cannot be parameterized because it's controlled by drop-down selections; there's nowhere to enter in your parameters. However, you can definitely use a coil (Create > Coil) to make a custom thread that you can control with user parameters. It's more work in terms of setup, but if you want to make your nut as fully parametric as possible this will help. As shown in the pictures below, you can define the coil by revolution and height, by revolution and pitch, or by height and pitch.  The rough example I have below used revolution and height, and the external triangular section shape. You should be able to find charts listing measurements for your preferred thread sizes online. 

Edit: I noticed that when I had a threaded hole (using the thread rather than the coil) and tried to change the hole diameter, the hole stayed the same size as well as the threads. Odd--I'll look into that!

Let me know how this works if you try it!

Best,

[agordon]

Many thanks for the suggestion ... I will give this a try and see if I can "represent' the thread form.  I'm guessing that I can "force" the nut to fit a bolt defined by the thread command by ignoring any interference (or editing the spiral).

I'll let you know how I get on.  Tony

[TrippyLighting]

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@Anonymous wrote:

I feel badly for asking yet another question ... hoping the welcome mat isn't wearing out soon!

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Don't 😉

[drawing-admin]

Just used this, thanks - great solution.

Jon

[hdvideo2015]

I thought using parameters to create the hole and then adding threads would be a workaround for not being able to use parameters in the threading dialog.  But as you found, changing the hole size does not change the thread diameter. 

Have you been able to look into why that doesn't work?

Ed