Hi,
A bit of background first...
The motors I currently have on my milling machine are only 1Nm, with a Unipolar driver which I've just sold to raise money for the new stuff. These motors are mounted to the side of each screw and connected via timing belts etc to give a ratio of about 1:2 (I tried various ratios). With this setup the maximum feedrate I could get was 1.4mm/s, and that was pushing it. This is with the standard 2.5mm pitch ACME screws that came with the machine.

Anyway, I've finally decided to buy 3 (or 4) new stepper motors and drivers from Zap so that I can get a higher feedrate. I was about to buy them yesterday but thought I'd just check first:

PM752

SY60STH88-3008BF

I'll be running them at 72V. I'll probably experiment a bit with the pulleys to see what works best.
My question is what feedrate can I realistically expect to get with this setup (without ballscrews), and are those motors/drivers a good combination? I'd like maybe 25mm/s.

Might these 3.5Nm motors be better? I'm guessing not as Nema 34 are generally slower, being bigger?

http://www.arceurotrade.co.uk/Catalo...Stepper-Motors
(I live just a couple of miles away from Arc-Euro so those would be pretty convenient.)

Here's a link to me using the machine to turn something, just to show which milling machine I have (skip to the end of the video):

http://www.youtube.com/user/Jonbliss.../1/4wGDMSiZpyg

Thanks in advance...