Got a chance to have a look, yep taper pin ....

Thanks John

However, didn't cure the problem .... so wasn't that.
I'm now thinking that it has something to do with engaging the dog clutch at the wrong place?
When I first tested cutting a thread I tried 8tpi, which is the same pitch as the leadscrew. So after taking a cut I could dis-engage the leadscrew with the dog clutch, wind the carriage back and re-engage the lead screw. Of course as I was cutting an 8tpi thread and the leadscrew is also 8tp then one turn of the leadscrew matched one pitch of the thread being cut. Simple and easy.
But when I cut a 6tpi thread one turn of the leadscrew does not match the pitch of the thread being cut. At least that's where I'm beginning to think the problem is?
I'm not sure how to get around this, leave the lathe leadscrew engaged and reverse the lathe? That would be a monumental PIA with no reverse power. But would it work?
And what about all the other threads on the threading chart, do they also need the leadscrew left engaged?
Me thinks me needs a reverse ..... poo
