Quote Originally Posted by m_c View Post
The other part of the motor equation is voltage. Voltage is what gives you speed.

As a motor spins faster, the back emf (electro motive force - essentially voltage that fights back against the applied voltage) increases, so in order to maintain current (which is what give you the torque), you need to apply an ever higher voltage.
The driver handles all this, so all you need to do is set the current.


As for why the motor seems smoother at lower current, I wonder if there is a fault somewhere. Without having a motor or drive to substitute, there isn't really that much testing you could do. Measuring the resistance through the coils of the motor would test for any obvious electrical faults with the motor, but they probably wouldn't be that conclusive.


My comment about precision was although Macro photography needs accuracy, it's more a case of needing repeatability, rather than pure precision. You don't really need the position to be highly accurate, you just need it to be repeatable.
Oh good, glad to hear I'm not wrong about the driver setting the voltage automatically. OK, so I can safely increase the current back to where it was and eliminate that as a cause for this issue. That's another thing down, moving in the right direction!

Hopefully the manufacturer can shed some light but if not I'll see if there's anything obviously wrong when, or if, I take it apart. If it came to replacing the motor is there any motor you'd recommend?