The previous owner may well have used a smaller DP for the 127 to make it smaller to fit without fouling a cover or bench. Perfectly sensible way to do it though not often tried. If you have no other gears at all you might look at just getting a set for a mini Lathe (Arc sell sets) which will probably be cheaper. You probably also want to arrang to keep the 24/127 in play for fine feeding even if not doing metric threads.

I have put some photos of my Pools Major into an album. Currently it is buried under much stuff while my son moves house. I will endevour to measure the change gears when it surfaces.

Rob

Sorry this is a bit late. The change gears for the Pools Special are indeed 24dp. The back-gears are 16 dp. The set of change-wheels that come with the lathe originally were 2 x 24, 27, 30, 33, 36, 42, 57, 60, 90, and 96. Note that they increment in 3s rather than 5s like the Myford, so there aren't any thread cutting tables published other than the one on the lathe headstock.

There was an additional set that had 60, 66, 78, 84 teeth to allow 26 and 28 tpi threads to be cut. There was a metric conversion gear with 127 teeth. This allowed a large range of metric threads to be cut. Although the 127 tooth gear does seem to be enormous, it does fit onto the leadscrew, where it needs to be located to cut all metric threads.

I have a set of thread-cutting tables for the Pools Special, so could upload them for you (if I can work out how to do it!).

Kind regards.