I’m new to the forum as I recently acquired my X-Carve. I used to own a Shopbot PRT-96 that had a heavy steel Y-Axis and Z-Axis gantry and used a 3 HP router for a spindle. The PRT-96 had stepper motors were keyed and used a rack and gear instead of a belt. When I was looking at the Pulley connection on the X-Carve Stepper Motors, I was surprised to see that the shaft was smooth and didn’t have a key or at the very least a flat spot on the shaft. Stepper Motors create a lot of torque.
To test if your Pulley is slipping;
- Place a mark on the outside shaft with a marker.
- Use a piece of left over drive belt so you don’t damage the shaft and carefully tighten a pair of Vice Grips on the shaft to hold it.
- Then hold the drive pulley with your fingers and gently rock the Vice Grips back and forth.
You shouldn’t feel any play at all on the Pulley. See pictures below.
I couldn’t tighten up the Set Screws enough to make the Pulley hold on the Shaft.
The Solution is to Grind a Flat Spot
- Loosen the belts and make a mark where the Set Screw contacts the
- Use a hand held grinder, I have a Ryobi but a Dremel works just a good.
- Grind a flat spot on the shaft and then reassemble.
I used a little Lock-Tite on the Set Screw, but I’m not sure that was necessary and will make the Pulley difficult to remove later. After you put it all back together, do the Vice Grip test again.
Other references can be found on the web discussing this issue with stepper motors, one listed below;