I just got an old Ender 3 for cheap and wanted to replace the crappy extruder with a nicer bowden extruder of my (now) direct drive Kobra Max. When I connect the new stepper, nothing moves. It’s a longer stepper and a different manufacturer. Is the wiring different or VREF wrong or are there other reasons why it wouldn’t move? The driver is good, since the old stepper is still working.
Thanks for any help!
Afaik steppers don’t care about voltage. It’s about current since it’s all inductors inducing magnetic fields.
Nearly all stepper drivers deliver a constant current to the motor, or at least, it tries. While the nominal voltage needed for a stepper is essentially “irrelevant”, setting the correct voltage determines the current available for the stepper, by the driver. This gets a little different to work out since the current is generally “clipped” or “chopped” as part of the function of the driver. (Ohms law is only really applicable to a stepper motor when it is not moving, btw.)
A minimum voltage is still required to overcome back-EMF.
Without going into the maths, your voltage settings determines your available current, basically.
Steppers require a certain amount of voltage to maintain position, too little and it looses position/starts shifting, too much and it overheats and stutters.
Generally, steppers will only draw what they need, and not more. 3d printers usually have current limiting switched if something goes weird.