Here is a .3 mod 20T with a 3mm bore:
http://shop.osorail.com/product.sc?productId=2696&categoryId=93
This one a 2mm bore:
http://shop.osorail.com/product.sc?productId=3036&categoryId=93
Would you be able to slide that over a standard Kato muff?
Good point here, Chris. I notice they sell a big variety of Delrin and brass 0.3mod worm gears (many with a lot more than 20T, and if
I have the room, more is better). The teeth are angled, but they are specified to mate with their worms. i.e. They have 0.3 mod
20T worm gear that is designed to go with a 5.0mm diameter worm, and they sell the steel 5.0mm 0.3mod worms to match.
As for the muff, pish posh. I am already machining muffs out of Delrin solid rod for the other drivers, so I can just make one
to fit the gear. This is really starting to sound like the way to go. Just get a matched pair of 0.3mod gears, once I know exactly
how much diameter room I've got. The gear can't end up bigger than the diameter of the driver tread, which is 0.320" (about 8.1mm),
and it needs to be a little less or it will hit on the cross rails over turnouts and crossings. The 24T is 7.8mm, so that's the one.
Hmmm 4 x 24 = 96:1 overall ratio with a single gear. Not bad.
It also would not be hard to run a thin steel wire through the center of a Delrin tube, and cut two small notches inside
the bore of the NWSL brass gear to engage those wires, so the thing would never slip on the plastic axle tube.
