I'm new here so hello everyone. I'm working on some aluminium parts that feature a three start modified stub acme thread. The parts are cylindrical electrical connectors, so we will manufacture a mating pair of these threads, this is the thread used to couple the two mating connectors together. The problem is that I have a set of dimensions that we are currently working to that are not derived from anything that I can find in any 'standard' stub acme thread data charts (in machinery's handbook for example). The modified dimension set enables us to cut threads with an allowance for a 13um plating thickness. We have been producing parts to this modified set of dimensions for a while. I now need to derive another set of dimensions that will enable us to produce parts that will be subject to a 30um plating thickness. Can anyone offer some advice on where to start with this please? I am confused after looking at the simple formulae that can be found in machinery's handbook etc. Results to calculations do not match the dimensions I already have for the 13um data set. Hope this makes sense. I'd be very very gratefull for some guidance with this please I think we could potentially produce a working, mated pair of threads, but these could then fail to mate with our competitors parts. Cheers VB P.S. I could post the current data that I have if required.