Two stepper motors on one driver

I wanted to know if anyone has had success - perhaps on other CNC machines - connecting two stepper motors to one driver output (such as the two on the y rails). I am interested in the possibility of freeing up a controller driver for a future 4th ‘C’ axis use. Are there any negative impacts of this?

I reached out to BuildBotics, and part of the response is as follows:

“… you may be able to wire the two motors onto a single port thereby freeing up the fourth port for your tangential knife. Oftentimes (but not always) wiring two motors to the same port results in resonance problems between the two motors resulting in motor stalls. Unfortunately, you won’t know whether this is a problem until you try it.”

I appreciate any insights those with experience may have.


Personally, I would not do it directly. I would use a breakout board, but in theory it would work since there are no encoders being used for feedback. The only thing I’d maybe worry about is the fact that homing is apparently done via stalling the motors. (I haven’t got mine up and running yet to see exactly how the homing routine is implemented) Come to think of it, a breakout board might be a way of incorporating encoder feedback or servo drives without having to modify the controller hardware/software itself. Just thinking out loud …