Quote Originally Posted by 2e0poz View Post
servo's (the type in model aircraft) have been meshing aluminium and plastic gears for years.
Indeed, servos with aluminium (or other metal) gears are considered much better than their plastic equivalents. The model cars I use use aluminium and plastic gears and they're fine. I should think the pressure on the gears in this application is greater than that on a lathe...48dp aluminium gear with 500W going through it!

Anyway, I'll be interested to see this 4th axis in action when it's done. Have you considered keeping the original lathe motor so you can use it as a CNC lathe should the need arise?