Hi all,

I have an Al340-D that I have had for a while now. The last few times I have cut a thread on it I have noticed that the pitch is slightly out from what I intended. As an example. I just went down and set it up for a 19 TPI imperial thread, using the gear chart printed on the front of the lathe. After taking a scratch pass, I measured the threads and its 21 TPI.

Any ideas what I am doing wrong? I have the 60 tooth gear driving the 127 which drives the 57 on the lead screw (meteic 3mm pitch i think).

Photos refer. Cheers, brendan.
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