I'm using a G540 with Keling 381 oz/in motors (KL23H2100-35-4B) powered by a KL-4813 PSU rated at 48V/13A.

As the X2 CNC fusion kit hasn't arrived yet, I was playing about with a DOS program that I wrote (in borland turbo c++) to step one of the motors with a laser pointer connected to the shaft and noticed that the microsteps were variable sized - some larger than others. This was very repeatable and the pattern repeated every full step (10 microsteps).

Is this expected? Does the trim adjuster control this? I realise that a mass produced controller can't be expected to be perfectly matched to every stepper motor out there but am intrigued to know a little bit more about this.

I realise that a microstep will be giving me 0.0001" movement at the milling table so I'm not too concerned about non-linearity.

Finally, is it normal for a g540 powered stepper motor to "sing" a little bit? I assume this is due to the pulsed nature of the power circuits. The exact note changes as microsteps are applied. Are the bipolar outputs both run in sync from the same switched mode pulses?

Thanks for any info you can provide.