Quote Originally Posted by franco View Post
FWIW I made 5 gears including a 37/47 metric conversion pair from 75x10 aluminium flat for a 9x18 low powered lathe which does not get a lot of use, for cutting odd unusual threads - don't know what the alloy is. They usually run with cast iron gears, but occasionally I need to run two aluminium gears together. So far they have been completely successful, showing no sign of galling or excessive wear. I wouldn't suggest using them in an industrial situation, but for my occasional use they are OK. Some of them were cut with fly cutters and were much quicker and easier to cut than steel gears using this method.

It might be worth making one as a proof of concept guinea pig from aluminium if you already have it in stock to check how your indexing system works and keep it for a spare if you decide not to use it.

Frank.
I've done the same, made a set of transposing gears for my Boxford to cut imperial threads on a metric lathe.
( compound indexing the 127t was a good learning curve) the aluminium gears have shown no signs of wear at all over the last 7 years. just make sure no swarf gets between the teeth & lube regularly.
Steve.