They are the same as my M type Myford (Drummond) look on the bay for similar in Drummond lathe.

David

From the description, I think these gears are Myford, though they may fit Drummond as well. Once upon a time I had an ML1 and the description of these gears fits with my recollection of the gears for that, and possibly some of the subsequent models. The plain bore and face pins idea predates the keyway and keyhole shaped carrier for the S7 etc. The pins locked two gears together to allow a compound train to be set up.

For the ML1, I'm sure the plain bore was 5/8 inch diameter (as are the later ones), and the two axial holes are 1/8 dia, though I don't remember the PCD. I'd guess about 1 inch, if so the pins are 3/16 outside the bore. I don't remember the gear thickness either, I'd have said it was the same as the later ones (i.e. 3/8 inch) but I might be wrong, and there's no guarantee the wheels I had at the time were original.

I think I recall there is a description of the development of Myford's change wheels in Tony Griffiths' site http://www.lathes.co.uk.

I've just had a rummage in the drawer with my collection of Myford change wheels in it, and found two with the axial holes, Both have also got the keyway as well, so that proves absolutely nothing.

Hope this helps

Simon

I have some gears like that: they are DP20 the same as Myford ML7 and Super 7 etc but have the smaller hole and two pin holes like a Drummond. (But Drummond M-type takes larger DP14 gears as Bazyle said.) I have always assumed they were off an earlier Myford such as ML1 etc but not real sure. If yours are DP20, they can be converted to fit the Super 7 etc by boring out the centre and cutting the keyway using a boring bar with bit turned sideways and racking the lathe carriage back and forth as a makeshift slotting machine. Laborious but it works. I have done a few this way.