Metric Thread Cutting on Model 9A with Imperial Lead Screw

[Rodd Perrin]

Hi,
I think I have interpreted the section on turning metric threads with a Model 9A with an imperial threaded lead screw – but I thought I would check before getting the gears I need. I have done a search of this thread and haven’t found the answers for a 9A.
The “Textbook of Turning” has the attached diagram for the gears / lever settings for the various pitch metric screw threads.
So, if I am reading this correctly, to cut the range of metric threads, I need a 28, 32, 36, 40,44, and 48 teeth gear for the Stud Gear and a 56 tooth screw gear (not sure what is there now – I don’t have my lathe with me at work J). I already have the 127:100 compound gear, so don’t need one of them
Is this right or have I got things muddled up? I need to cut some metric threads and don't want to end up with a bunch of paper weights
Regards,
Rodd.

[pipeclay]

Yes.

[Rodd Perrin]

Ta....

[HavinaGo]

My one observation is that you probably have the 40 already as a spare on the stud (or the one in use) and the gear on the gearbox input - at least on my machine - is a 56.