Machinist Handbook
http://www.industrialpress.com/en/Ma...k/default.aspx
Look thru the book and find the thread you wish to make,it will have dimensions for OD and ID.
Set of thread wires.
If you turn the OD as per the handbook and are sure your threading tool is ground correctly,then use the wires to make sure the pitch is right.
http://www.threadcheck.com/pdf/3-wire-16-17.pdf
You don't need anything as exotic as whats show in the file,just a set of wires.
That will insure all of the parts have the same thread dimensions.
Thread the ID or "nuts" untill you get the fit you want.