By using a standard NEMA 23 motor mount on the XZ stage, you have a wide variety of choices for motors. There are pros and cons to using stepper motors versus servo motors. You can look it up on the internet for more info.

I've chosen to use stepper motors because they are easy to implement and don't cost as much as servo motors. I'm currently using Vexta PK266-03A motors that I bought from Interinar for $38 each. Other motors will work for you as well.

There are plenty of sources of info on stepper motors on the internet, and I won't repeat all the info here. Here are some things I think are important for this application:

• The newer "square" stepper motors are better than the old "round" stepper motors for micro-stepping.
• Torque of 50 oz-in is about the minimum. The PK266-03A motors are 127 oz-in which is more than adequate.
• The motor current is generally related to the torque. You don't want motors that take too much current or you'll have to get heftier drivers.
• Look for motors with low inductance! This is important for micro-stepping. Our application uses the motors turning at very low speeds, and you want smooth micro-stepping. Higher inductance takes a higher voltage power supply (often more than the driver can handle) to get smooth micro-stepping.
• 1.8 degree (200 step) motors are adequate. 0.9 degree (400 step) motors might be better, but not if they have more inductance.
• 4-wire, 6-wire, or 8-wire motors are all OK.