Threading help please

[Investigator]

Here's a quick and dirty diagram of what I need:

So, I have 1" rod and 1" tube. I'm making a screw in cap. The tubing is machined as shown in the drawing.
I need to find the major diameter of the external threads on the rod so I can turn it to that dimension then thread. The minor diameter of the internal threads can't be less than .900"

If i understand the MH correctly the depth of external threads is .61343 x pitch, or for 28 tpi it should be .61343 x .03571. That gives me .02190" for thread depth.

If that's right then I can turn the rod to .922" and thread. Does that look right?

 

[Red96]

0.944"? There's .022" thread depth on each side of the diameter, so total of .044" additional diameter needed is what I come up with. Leaves your female thread with pretty thin walls.

 

[markba633csi]

Looks like the stock will have to be larger than 1"

 

[RJSakowski]

If I am not mistaken, you will need to double your thread depth to get the OD. A tap drill for a .936 x 28 tpi with a 70% thread would have a diameter o .936-1/28 or .900. A 100% thread engagement would require a slightly larger o.d. of .944.