External Threads

[jroma1]

When cutting external threads,is the outside diameter cut to the "Basic Major Diameter" listed on the charts?
Example: Do you turn down the work piece to 0.236 inches for a M6 x 1.0
thread?
Also is this diameter the same whether you are cutting threads with a die compared to cutting threads on a lathe.

I would appreciate any comments or suggestions.

John

[fatal-exception]

Turn the rod down to a value between the min and max OD as listed on most screw charts or in the Machinerys Handbook.

Yes, you would use the same diameter regardless of how the threads are cut.

[a1woody1]

When cutting an external Thread the outside diameter the same as the one on the charts for Instance 5/8 x 11 world be turned to .625 I usually cut about .003 to .oo4 smaller, I can only speak for myself but this causes less interference when you go to put it in a mating female part such as a nut the same size, it is a good idea to have a mating part that you know is to size that way when you are finished with the thread you can check it to make sure it fits! For Metric Thread, use .03937 for instance 6 x .03937 = .23621 to go back the other way you would divide

a1woody1

[fatal-exception]

John, according to the machinerys handbook:
M6x1-6h: maj dia max = 5.974 (.235"); min = 5.794 (.228")
min dia max = 4.891 (.193"); min = 4.596 (.181")

If your cutting with a die, you can relax these dims since the die will correct. If your threading on the lathe, be within the above tolerance or it will take trial and error to fit properly.

a1woody1 - you can use your generalization for large threads (1/4" and up) but for smaller threads, -0.004 could be way out of tolerance.

If possible, you should consult a real screw chart that shows the limits of both the major and minor diameter.