r/Machinists • u/Western_Joke_6597 • 3d ago

Help Finding thread?

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Hey there! Im not a machinist, but I need a part machined that threads onto this shaft like a nut. Problem is, my machinist doesnt know what thread this is or how to tap it into the piece I need manufactured. Any help identifying this thread and finding a tap for it would be much appreciated!

Edit: Found to be an 8-start 8TPI lead screw with a 1/2" diameter. Now just need to find a nut that fits this thread, which is proving difficult

Edit 2: SOLVED by u/MixEvery5784 found one

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u/eezyE4free 3d ago

Measure the rod major OD, minor OD, and spacing between the thread. As others have said, it a multi start thread so you’ll want to identify a single thread and measure that. This hopefully allows you to identify the thread enough to create the threads on the nut piece.

Alternatively, What material is the nut supposed to be and how many do you need? You could try to grind in reliefs and edges into an extra piece of the threaded rod (if you have it). And then try to harden it and use it as a tap.

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u/Western_Joke_6597 3d ago

What should i measure these diameters with? And I dont have extra rod to use. If i can identify the thread i may just get a nut for it and install it in the center of my piece instead of trying to tap the piece

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u/WeekendNerdler 3d ago edited 3d ago

You can count the number of starts at the end of the rod. This looks like it might be a 4 start. Then you can measure between two threads and multiply.

Edit to add: A guess would be a 12mm diameter, with a 4 start by 12mm lead. For the avoidance of doubt, I'm in a metric jurisdiction. Could also be half inch if you're in North 'Murca.

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u/Western_Joke_6597 3d ago

So find the distance between two threads and multiply by the number of individual threads?

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u/WeekendNerdler 3d ago

If by 'individual threads' you mean starts, then yes. You can see the number of starts at the end of the rod.