[mauribastidas]

In this moment I’m assembling my first CNC and I have some doubts about how to couple the motors to the axis, I’m going to build a small machine 70”x 40” x 20” and I have some 640 oz step motors and some screwballs to do it, however I wonder if it is OK to couple using shafts coupling or to use timing pulleys with some kind of relation, what is the best way to do it , thanks for your help.

[PaulRowntree]

I have direct drive on all three axes, but it is hard to align, and I am certain that it will shorten the lifespan of the motors as a result. If the leadscrew is properly supported on its own bearings, then a direct connection requires you to align the motor on exactly the same axis, at exactly the right distance, or else you will be applying unnecessary stress to the motor. Just tightening the motor down its support will change the alignment to some degree. Pulleys or flexible couplers accomodate that last bit of misalignment. Plus, they can give you a way to use the motors in their prime torque regime, like a car transmission does.

[acondit]

I use Lovejoy connectors the seem to be virtually zero backlash but still allow for very slight misalignment of shaft and screw.

Alan