47/37 gear set for approximate metric threads on Harrison L5 lathe

A special remix of single gears to produce a 47 tooth and 37 tooth gear pair to enable metric threads to be approximated on a Harrison L5 lathe.

The configuration on a lathe is described well here:
http://www.lathe.com/metric_threading.htm#Diagram

If you need to tweak bore and keyway dimensions, you could use the customizer version this was derived from and print as two separate gears. Or you could download the SCAD files and make changes manually in OpenSCAD.

I haven't made one of these, and I don't need to because I have an original 127 tooth gear. If you make one please comment on your experience.

Update: Pushing the envelope a bit more - I have also worked up a design for a 3 piece jigsaw of a full sized 127T gear http://www.thingiverse.com/thing:1802545 that is printable on a 200mm square bed. This can deliver exact metric pitch threads (provided you have the other gears required - 40T, 50T, 60T and 63T).