Mini lathe, has anybody converted to CNC?

[JFettig]

Mark, my lathe says 400W on it for the motor,

Here is a graph to show you why I say you dont gain anything in torque but loose top speed:
I picked 2 speeds and doubled them, you double the torque for the high speed as if it was on a 1:2
Basicly you select 300rpm direct drive, you get 150oz-in, go 1:2 and you need 600rpm to get 300 at the screw which your getting 75oz-in out of the motor and 150oz-in at the screw. same goes with the 450 that I marked out.

Rotary, I am looking at getting some ballscrews for my machine, but for sure I will be going with ball bearing end blocks for my screws, right now they are just sleve bearings which probably reduce my capabilities some too.

Jon

[RotarySMP]

Jon, the motors sold in the metric countries are 250W for the 7x10 and 7x12 and the 350W from the mini mill for the 7x14. The motor casing on mine sure looks the same as the 400W motor on the Grizzly on www.mini-lathe.com. I wonder if there is really a difference, or what the real power is?

One thing you are missing with steppers is the voltage. What voltage is that graph for? Normally the motor curves I have seen (I have vexta's) have curves from 24 and 36 V, which is quite low. If you run low impedance motors with a higher voltage through a good chopping driver, the torque curve flattens out considerably.

The master of this stuff in Marriss, who is a exponent of good quality low impedance motors geared for high rpm, and high power.