The belt we use in our Bantam Tools Desktop CNC Milling Machine's Spindle Assembly is very durable and can likely last the life of the Spindle. There is a very slight possibility however of it failing during the life of the spindle. In this case, it is a much better decision to replace the belt instead of purchasing and replacing the more costly new spindle assembly.
If you are having performance issues with your machine and you have reached out to Support@Bantamtools.com to get feedback, it is possible that the support technician might ask you to go through some of the steps below in order to gain access to the belt drive area so that you can inspect the belt for damage. In the case there is damage, you can go ahead with the replacement by ordering and replacing the belt following the rest of the steps.
You can purchase replacement belts at out online store here:
Jog the gantry to a little higher than the lowest point to allow the triangle nuts to come out of the pocket. Note: The gantry Z-axis will fall, so support it before it moves that small amount)
Turn off the machine.
Disconnect Motor and remove M4 Screw with a 2.5mm Hex Key. (see picture)
Remove 3 m4 screws that attach the ABN (triangle shaped nut) to the Spindle Using the Short 2.5mm hex key. (make sure the hex key is fully inserted to avoid stripping the screw)
- Spin the ABN nut all the way to the top
- Using a 4mm allen key remove 4 M5 screws( see picture)
- DO NOT TOUCH THE 2 SET SCREWS IN THE FRONT( see picture). This allows for the motor to keep its alignment with the spindle pulley when it is remounted.
- Tilt the mount back and remove the mount from the machine.
- If you have a 2 piece spindle - (see picture below) continue to step 16.
- 2 Piece: Remove the 4 Button head screws( see picture)
- Remove bottom plate
- Replace the belt with a new one and put the plate back on. We recommend cleaning the area during this process.
- Replace plate and M4 screws and go to step 18
- 1 Piece: Remove all 8 screws on top plate using the 2.5mm hex key.
- Remove plate (keep in mind motor doesn't have to get removed)
- Remove the belt and add a new one.
- Put the plate back on and tighten down the 4 inner M4 screws while keeping the belt positioned in the spindle pulley area- be careful not to pinch the belt under the plate when tightening. Secure the outer 4 m4 screws loosely in order to allow enough movement to align with the below spindle assembly.
- Position the motor and plate back into position and the Tilt motor mount backwards, inserting the belt over the spindle pulley. You can use the hex key to help you guide it in. Rotate the spindle to make sure the belt is located on the spindle pulley.
- Insert M5 screws and tighten down motor mount plate.
- If you’ve tightened the belt multiple times, this becomes a CHORE because of the alignment on the 2 piece sub assembly and position of the M5 screws because of the tightness of the belt. I used a sharpy to mark where I could actually thread the screws and due to the original tightening, I was roughly 0.100 off, so I could not thread the screws without using the belt tensioning tool to pull it back.
- Recommendation on the 2 piece assembly. Remove the M4 cap screws and move that guide back in so the belt is technically loose when reinstalling the motor and plate back into position.
- Reattach the motor wire guides
- Bring down the ABN (triangle shaped nut) to the bottom and soft thread the screws into place.
- Push the spindle as far up as possible to be able to still fit and rotate the allen key. You do the final tightening at this location so that the ABN is set properly in relation to the lead screw and the rails.
- Tighten down the M4 screws with the 2.5mm hex key.
- Plug the motor back in and turn on the machine.
- Home the machine.
- Tension Belt: https://support.bantamtools.com/hc/en-us/articles/360059977333-Re-Tensioning-the-Drive-Belt