You're probably thinking "What is this guy talking about?"
I have a job to tackle that is a bit different then the normal than just a NPT Taper thread or Straight Thread. A bit more complicated....... Want to see if anyone has tackled something similar.The job to make conduit for the electrical industry and they need something specific.
Customer is asking for a 4" NPT Taper on 1st end of shaft that will continue threading to a 4" NPTS Straight Thread then back to a 4" NPT Taper for the other end of the shaft. The NPT Taper threads on each ends are standard engagment, but the main thing is to be able to thread a 4" NPTS straight thread coupling all the way across the entire shaft which is 7" O.A.L.
You might ask....... "if using a 4" NPTS straight coupling, then why thread taper the ends?" Reason is because they still use a locknut inside the elect. boxes that need a handtight engagement.
1) I have chucking stock to be able to thread entire 7" length. I will set up using my tailstock on one end and 7 1/2" out of chuck for threading.
2) I know I probably can't use a G76 cycle for this because of the amount of variables here. Probably have to use a G32 cycle if not mistaken.
I have not written G32 cycles for threading in the lathe. Mostly G76
2-line cycles for all threads. That is why I ask for some help.
So program would have to start a G32-- 4" NPT Taper, then continue threading a 4" NPTS straight thread across the shaft, and lastly, another 4" NPT Taper thread downward to the end of 7" O.A.L of shaft.
I don't know what kind of machine you have...
This is sort-of similar. (and probably a bit more complicated) But might give you some ideas.
"http://www.youtube.com/watch?v=ACvRilmIKDQ"]YouTube - Variable Diameter/Variable Pitch ThreadCutting with EMC2