Are the Zapp 3NM steppers good with their PM-752 drivers?

[Jonathan]

you need 66% of the total motor peak current... so 3 steppers at 4A/phase = 3 * 4 *.66 = 7.9A. @ 60v thats 420VA

remember that measuring phase current with an analogue device will show the RMS phase current. With a digital meter you are unlikely to get a useful reading because its highly spikey.

I thought it was 8 amps per motor, since there's 2 phases?
Anyway, I got lucky and won a 500VA toroidal transformer for £20 on eBay so I'll be using that.

I changed the pulleys round (had to bore them out to the right diameter and stuff) to get 1:1. Now I'm getting 42mm/s on the X axis :)
Bad news is the Y-axis for some reason refuses to even go at 25mm/s without stalling the motor. Not really sure why, maybe something to do with the belt tension and how tight the nut is...
Not tested the Z yet.

[irving2008]

I thought it was 8 amps per motor, since there's 2 phases?
Anyway, I got lucky and won a 500VA toroidal transformer for £20 on eBay so I'll be using that.

I changed the pulleys round (had to bore them out to the right diameter and stuff) to get 1:1. Now I'm getting 42mm/s on the X axis :)
Bad news is the Y-axis for some reason refuses to even go at 25mm/s without stalling the motor. Not really sure why, maybe something to do with the belt tension and how tight the nut is...
Not tested the Z yet.

No, thats peak current. In general the 2 phases are never both powered fully all the time so a sort averaging occurs and anecdotally (although Mariss of Gecko fame did show the maths once) its 66%!

Its usual to quote feed speeds in mm/min for milling - so 2520mm/min is good, 1500mm/min isnt bad tho

Strange... if you haven't already, try swapping driver channels to validate its not a driver issue, then motors (assuming they are the same) to validate its not a motor issue

[Jonathan]

(although Mariss of Gecko fame did show the maths once) its 66%!

Thanks for the clarification. Do you by any chance have a link to the 'maths' behind this? I'd be interested to see..

Strange... if you haven't already, try swapping driver channels to validate its not a driver issue, then motors (assuming they are the same) to validate its not a motor issue

(I quoted the feeds in mm/s since personally I think it's better to work with smaller numbers and easier to visualize, but I'll endeavor to stick with the convention from now on)

I've only wired up one driver so far, so that can't be the issue. I'll try swapping the motors though. All the motors are the 3N-M ones.
The handle for the Y axis (before I removed it) did seem a little harder to turn than the X-axis so I may try loosening the nut. I tightened it to reduce the backlash. Annoyingly to get to the nut you have to take the bed off the machine and all sorts...takes ages :(