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Hi Greg, Got it, thanks for the advice. I’ll include the thread specs in a drawing to ensure proper accuracy.

[Perry Grant]

Hello, I have a modeled anti-backlash lead screw shown in the image below:

My question is: when the thread is already modeled in the CAD file, is it still necessary to include a detailed drawing with the thread’s specification (e.g., pitch, diameter, class) for the manufacturing process? I’ll have my parts procured by an external provider.

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[Greg Paulsen]

If the thread is standard, we don’t recommend modeling it in the CAD provided and instead calling it out in a technical drawing. Threads have different sizes and classes, which relate directly to how the thread will be manufactured and inspected. Modeled threads may not fully incorporate the nuances of a manufacturing process; even if we have the right die or tap for the thread, it becomes a mess to chase if already formed.

In your drawing I see no clearance between male and female thread features. That’s not the reality of good thread design, as clearance is always necessary, and features must have tolerances. Again, this is a good reason to call out the thread requirement on a drawing so there is something to inspect against.

If this is a 3D print I would recommend modeling coarse threads, especially if they are custom, but also incorporate adequate surface offset to compensate for the selected process.

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[Perry Grant]

Hi Greg,

Got it, thanks for the advice. I’ll include the thread specs in a drawing to ensure proper accuracy.

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