Quick Change Gear Box

I have a Myford Super 7 with a quick change gearbox. The lathe and the gearbox are both imperial. I got the chance to buy a long bed super 7 but when I got it home the lathe is a metric lathe and the gearbox it Is fitted with is imperial. Does that mean I won't be able to cut metric or imperial threads on it? Is there such a thing as a myford metric quick change gearbox?

Any help is welcomed, Alan

Thread cutting is all about ratios between the spindle and the leadscrew. If you have a metric leadscrew that is set to rotate 1:1 with the spindle you will get a metric thread. If you have an imperial leadscrew set to rotate 1:1 with the spindle you will get an imperial thread. The intervening gearbox just changes the ratio rather than the measuring system.

Martin C

Good evening, Alan,

Before you go any further, I suggest that you measure the pitch of the thread on your lead-screw.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 20/09/2023 20:48:03

Pretty sure both metric and imperial machines have an 8tpi leadscrew and imperial gearbox, you can cut metric threads using conversion gears and of course imperial threads straight off the gearbox. The changewheel set up will be as in the chart in the changewheel guard. Brian Woods book on scewcutting will have full details ( highly recommended).

Edited By Dave Wootton on 20/09/2023 20:51:26