What current to use for MAE HY200 3424 0310 Stepper Motor?

Hi, I have a Denford Novamill with a routoutcnc Mach3 conversion - I recently replaced the X and Y steppers and drivers (DM542T's) to solve a lost steps issue - it worked. Up until now I haven't had any issues with the Z but yesterday I got a repeated stall on the Z, so I'm going to replace the driver to see if that helps. I've already slowed down the motors, increased the pulse time etc.

The Z axis has a MAE HY200 3424 0310 which is rated 3.1A. Currently it is running on 2.5A as that is the maximum the routoutcnc driver can output. The new driver is capable of up to 4.2A, so I'm hoping to get better performance out of the stepper once upgraded.

My question is this:

The stepper's documentation says that its rated phase current is 3.1A. Does this mean it is 3.1A per phase, or altogether? If it's 3.1A per phase does that mean 6.2A total if wired in parallel, and I should be alright running the stepper at 4.2A?

Thanks

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One answer is that there does not seem to be any particularly well-defined standard or convention for giving these figures. Frankly, it's a bit of a guess what the manufacturers of motors and drivers actually mean when they give a figure. Fortunately, it doesn't actually matter too much - nothing's going to go bang if you are a bit over, and you will just lose a bit of torque if you are under. The technique I have used quite successfully is to start with a nominal driver current a bit below the nominal rated current (whatever that means) of the motor, and let it run for a bit. Leaving the motor stationary can be a bit misleading as a lot of drivers will reduce the motor current to 50% or so if the motor is stationary. Then feel the temperature of the motor. Steppers are quite happy at higher temperatures than you might expect, and if it is cool enough to be able to hold then it is OK. Try increasing motor current a bit and test again. Once the motor is just too hot to hold (which will be around 60C) then you have probably reached a maximum, and you might want to go down just a little from there. I have no idea what current my router steppers run at, just that using this technique will get max torque out of them without them coming to any harm through overheating.

Others might take a more analytical approach, but my way works for me!

Thanks for the advice - will give that a go!