help with gear calculations

Sorry for the confusion, the pinion gear was made very kindly for me by Pete.

I have added the images of the CVA lathe as this was the project that I needed the gear for and I all but finished it at the weekend (in hindsight perhaps I should have started a new thread).

Howard, thanks for your comments. I must confess I didn't appreciate locking the gearbox into one speed and using a VFD to control headstock speed would mean I couldn't get certain thread pitches. I assumed the speed from the gearbox controls the rate at which the thread is cut but the gearbox on the headstock controls the ratio between leadscrew and saddle speed.

Could you give me an example where you would have to set the gearbox driven from the motor to a specific speed to cut a certain thread so I can better understand you.

Many thanks

Philip.

I don't think Howard is suggesting that, he's saying that given the obvious wear in the handwheel pinion and the reported noisy headstock gears he's hoping for your sake that the screwcutting gearbox at least is in good condition so that you may have the full range of feeds and cutting pitches.

I obviously misinterpreted Howard's post. I have had the lathe for 15 odd years so it's not new to me. It has always been my ambition to strip it right down and replace worn/broken parts and get the lubrication system working properly and get it looking top notch. There are no issues with the feeds/threads gearbox, the problems were in the gearbox driven from the motor.

Philip.

Thanks Peter!

Being extremely skilled at teaching granny to suck eggs,I wanted to make it clear that the Norton gearbox would provide a number of settings, possibly in combination with a few change gears, to enable a range of screwthreads to be cut.

The VFD will obviously allow the rapidity with which the thread is cut, or the rate at which the saddle moves along the bed when cutting. But the Norton box will determine the ratio between the speed of the chuck and that of the Leadscrew, or Feed shaft into the saddle.

Or am I digging my hole even deeper?

Howard

Edited By Howard Lewis on 03/09/2019 18:16:08

I understand what you mean now Howard, I didn't appreciate that the gearbox bolted to the headstock was called a Norton gearbox. I subsequently googled it and all became clear.

Philip.