Cutting Wrong Thread Pitch SB9a

[Wjw159]

I am going out of my mind! My machine doesn't exactly cut the correct threads per inch it is setup to do. I set up for 14 tpi and the scratch pass doesn't line up with the gage. At 7 threads its off about half a thread. Somewhere between 14.5 and 15 tpi if I try to measure with calipers.

I can't find anything wrong with the setup. The first lever is in A the second lever is in the last hole.

Under the cover I have a 20 tooth going to 80 going to 56 input to the qcgb.

I can't figure out how it COULD cut this if I wanted it to. Is my setup right? Something else wrong? Lathe just too worn out to thread?

14 tpi - Album on Imgur

 

[BDRetz]

There was a thread a couple months back with a similar issue. The gear on the end of the leadscrew in the gearbox was flipped and engaging the wrong gear. Something to check.

Ben

 

[BDRetz]

Found the thread
Strange threading problem

Hope it helps
Ben