I'm considering the purchase of a Sieg X3 and converting it to CNC. I was wondering the pros and cons between direct coupled stepper motors on the X, Y, & Z axis and offset steppers with a gear and belt?
Well, for starters - using a belt and pulleys allows you to effectively multiply the output (torque) potential from the motors and increase your potential accuracy. The cost of doing so is that you loose some speed.
Consistency is a good thing....unless you're consistently an idiot.
You could just use a bigger stepper with direct drive. The normal issue with steppers is they are to slow for decent rapids so gearing down just makes it worse.
The critical issue with steppers is you need a bit extra in the size department in order to avoid the risk of lost steps.
A direct drive will give more than enough accuracy for the capabilities of an X3.
Just some thoughts from a novice.