On 14 Jan 2005 20:27:53 -0800, wrote:

Several sources have suggested using a 37/47 gear combination
which is susposed to produce "2/100 of 1% accuracy"
[see http://www.lathe.com/metric_threading]

We can't find a source for those gears either.

GmcD
======================================
I think there might be a small market for 127 tooth 1 module gears
among the
owners of mini-lathes.

Like me.

Did you try compound gearing for a 80/63 ratio?
That is maybe close enough for hobbiest work anyhow.
Since 80 = 20 * 4 and 63 = 21 * 3 you can build a compound gear
train from a 20 tooth, 21 tooth, and another pair of gears with a
3:4 ratio.
Finding 20 tooth, 21 tooth, and either 15 tooth or 25 tooth
gears should be easier than finding 127 tooth gears.
80/63 = 1.2698 Basically this gets you within .0015 percent.

Maybe someone will have enough ambition to develop electronic gearing
for a mini lathe. Even if it doesn't have the ball screws for CNC
threading, it could work with electronic gearing and a stepper driving
the lead screw...
But I digress.

Pete