In my search for replacement parts I reached the “stepper motor” phase. So I set out for a search and ended up at my favourite local 3D parts retailer selling what I think are Chinese B-brand stepper motors. While browsing through their offering I noticed they sell small (40mm) and very small (34mm) NEMA 17 replacements, of which the very small looked extremely attractive as an extruder stepper replacement because of the smaller weight and hence smaller inertia of the X-axis. While googling for answers if the smaller torque would be a problem on Wade’s type of geared extruders (the jury still isn’t out, it seems) I also found that the different current rating is of extreme importance and would need to be adjusted in the firmware as well. So, apart from the question if this is a wise thing to do, I’d like to know:
- Is the different current rating adjustable with M907 on the mini firmware? This would relieve me from having to build and flash my own firmware. This topic seems to convey negative results from M907?
- If so, what are the units of M907? A, mA, % or a byte value?
- If not, what particular defines would have to be changed in the firmware? The topic aboveonly mentions DIGIPOT_MOTOR_CURRENT in byte values, but what value is 255 in the Mini firmware?
- And last but not least: the mentioned stepper motors are rated 12V and I know the Mini has a 24V power supply, does this hold for the stepper motor drivers as well? I read the motors are current driven and stepper drivers seem able to adapt for different voltages, is this true for the drivers on the mini rambo as well?
Long story short, would I be better of ordering this Lulzbot 34mm short NEMA 17 replacement (which has a rated voltage of 2.8!?) or let go of the idea entirely?