[Captain Crunch]

I really need some help with this. I have a project with two mating parts with a 1 3/4"-8 Acme stub 3G thread. I do not have gages or the correct tool but I do have a regular acme tool with the 29 deg included angle.

The external thread is 1.750/1.7437 od, and 1.7045/1.6959 pd. How can I check the pd on this. Is there a MOW? Wire size? If the tool angle is right, cant I just control the minor dia? This is what I would like to do but don't know what that dimension is. On an acme thread, the root dia and the minor dia are the same, right? Its probably in the handbook, but I don't have it right now. For the external thd, I need two things please.....
1. The thread minor dia
2. The width of the land at the thd root(for stub thd) plus allowance if possible. I can compensate in my program to widen to correct dimension.

The internal thd--the print says 1 3/4"-8 stub acme -3G BD1.675/1.681 minor dia. I am not sure what the BD means-sounds like those are the minor dimensions.

3. What is the width of the land at the major dia of the internal thd(plus allowance if possible).

If I can make the OD thd correct, I can use it as a go gage on the other part. Any other ideas for checking the ID thread.

I know there are a lot of smart guys in here-please help me with this. It is a hot prototype for an important customer.

Thank you.

[txcncman]

3 threads on the same topic within 10 minutes? You are kidding, right?

[jeff 888]

If I can make the OD thd correct, I can use it as a go gage on the other part. Any other ideas for checking the ID thread.

I know there are a lot of smart guys in here-please help me with this. It is a hot prototype for an important customer.

Thank you.

You could go to your local hardware store and buy a part with that thread on it and use that as a go gauge and just make it a snug fit. Or buy a set of tri rolls and go/no-go gauges for this thread.