This is a query, as I don't have a firm idea either way. The question is this: On my 3D printer the 2 Y steppers, assuming a single available driver, were simply wired in parallel, with one pair reversed to make it drive correctly. My later card had 4 drivers available so the Y steppers had a drive each. Which is better & why? Now on to my CNC Router. I have a breakout card with 4 stepper outputs and 4 separate drivers, but now I want to run a 4th axis, so back to one output for the 2 Y axis motors. Do I parallel them at the output of the driver, or do I parallel the inputs to 2 drivers, buy an extra driver, thereby giving the steppers a driver each? I don't think I've seen it mentioned in any construction presentation and I perused many..
Current wise, it is better to use a single driver per stepper, the driver might not be powerful enough to drive two steppers. I would parallel the output of the BOB and add another single driver.
On a single driver, if you don't have your current limiting set correctly, it could fry your driver. Even if you do, it could overload your driver's current capacity and you'll lose torque and skip steps. On a 3D printer, it probably isn't much of an issue, but on a router, where the motors are going to encounter resistance and draw current, definitely better to beef up your power electronics.
You can also wire two motors in series to a single driver, this way they get the same current, but effectively each get half the drive voltage. The lower voltage reduces the maximum speed you can run the motors. In my setup the series wired Y motors can still run at the maximum speed my controller (grbl) can produce steps .
