Making a threading dial

[Mayhem]

Thanks Dave - I have some counting to do!

I wont be back in the workshop until Friday, so I'll work through this then. I'll need the time to read this again a few more times. Your assumptions are correct in that it is an imperial lathe, with an imperial leadscrew (metric wasn't invented when this old girl was made). The leadscrew is 2tpi but I will double check to make sure.