Quote Originally Posted by Agathon View Post
Thanks for the reply. What's a "charge pump"?

Re Clearpath - they are true servos rather than hybrid servo/steppers. I take your point about interference. I might pose the question to Teknic and see what they say - they've been really helpful so far.

There seem to be as many opinions about drives and motors as there are drives and motors. I did canvass this forum and others quite extensively before buying drives and the consensus seemed to be that Leadshine AM882s at 70v was the way to go. Still, the Z axis is fine, and the X&Y drives can be redeployed. If I do make some change to the X and Y drives it will be to servos - not poncing about with these poxy stepper things any more
I'd like to get my hands on one to see, but the torque curves look more akin to those of a stepper system, than a servo system. Stepper and brushless motors are very similar, it's just stepper motors are synchronous (which is what gives them the detents), while servos are a/non-synchronous, which means you don't lose power/torque overcoming the detents.

Regarding the Nema 23 v 34 argument. Compare them running similar voltages. You'll generally find Nema 34 graphs are using a high voltage driver, while Nema 23 are done using a relatively low voltage driver.
I've just had a quick look to see if I could find a couple graphs to do a comparison, but the Nema 34 graphs I found were mostly using a 110VAC supply (about 155VDC), while the Nema 23 ones were using 30-40VDC supplies. At those low voltage, torque drop of is very noticeable, and crippling Nema 34s with only 70VDC also makes for a very similar torque drop-off. You need voltage to over come the back EMF at speed. Without that voltage, torque at speed is very limited.