Possibly a dumb question, but, with regard to the torque curve shown in http://www.cncrouterparts.com/cdata/...rque_curve.pdf it may seem that the best rpm to run that stepper is; well, as low an rpm as possible.

However, based on the fact that horsepower is proportional to rpm x torque, I calculated the following (rpm and torque values from the spec sheet above):

Code:
RPM	Torque(N*m)	power (no unit specified)
60	5		300
120	4.6		552
240	4		960
360	3.6		1296
480	3		1440
600	2.4		1440
720	2		1440
840	1.6		1344
960	1.4		1344
1080	1.2		1296
1200	1		1200
Based on that, the ideal range for this motor looks to be between 360 and 1080 rpm; indeed if I actually wanted a 60rpm output, it would be better to run the stepper at 600rpm, and gear it down by 10:1. Given (unrealistic) 100% efficient gearing, the 2.4Nm at 600rpm would become 24Nm at 60rpm.

Am I on the right lines here? My question is probably "in general" in relation to steppers rather than this particular model; I have no prior experience with them, but I'm considering having a go at a DIY CNC build.