Posted by Ajohnw on 13/04/2016 10:23:59: I recollect Rod cutting helical gears like this with a much coarser pitch so had to use a handle.
Indeed. That was using a milling spindle powered gear cutter – analogous to thread milling. Driving a single point threading tool from the leadscrew handwheel is probably going to be difficult since the mechanical advantage is all the wrong way. Personally, I'd do as John suggests and set it up in the conventional way to cut 5tpi – just be aware of the issues, take it slowly and carefully and see if it works. A hand crank on the lathe mandrel is always a useful thing to have and I often use it for thread cutting, it will give you some feedback as to how the job is going before anything breaks!
HTH,
Rod
Edited By Roderick Jenkins on 13/04/2016 13:19:28