Belts and pulleys
The G1 motion system uses GT2 belts on the Y axis and an X axis chain drive for the gantry. Understanding each is important for diagnosis and maintenance.
Y axis — belt drive
Section titled “Y axis — belt drive”Components
Section titled “Components”- Two GT2 timing belts (one per Y rail)
- Drive pulleys on the Y stepper motors
- Idler pulleys at the opposite ends
- Belt tensioners (adjustable screw or eccentric)
Specifications
Section titled “Specifications”- Belt type: GT2 (2 mm pitch)
- Tension target: firm but not rigid — deflects a few mm at mid-span with light finger pressure, like a guitar string at moderate tension
Signs of belt issues
Section titled “Signs of belt issues”- Layer shift in Y direction during fast moves
- Rounded corners that should be sharp
- Clicking or clunking during Y moves
- Dimensional inaccuracy in the Y axis
Tensioning
Section titled “Tensioning”See Belt and chain mechanical issues for the full tensioning procedure. In brief:
- Power off the machine
- Locate the tensioner at the idler end of the affected belt
- Adjust in small increments (¼ turn)
- Verify by hand-moving the axis — smooth, no binding, no deflection
X axis — chain drive
Section titled “X axis — chain drive”The X gantry uses a roller chain (called “Power Chain” in the assembly manual) instead of a belt. It has a tensioner knob, but the knob has limited travel.
Assembly notes (from official manual, step 1.4B)
Section titled “Assembly notes (from official manual, step 1.4B)”- The Power Chain ships with both white and coloured zip ties — remove only the WHITE zip ties before installation; leave coloured ones in place
- The chain hangs on hooks on the upper frame, then is screwed to the upper frame and down to the gantry
- Two M6X20 CIL screws are already embedded inside the chain for this purpose
- The frame tensioner (step 1.6) uses a metal cable (QS) that must be tightened via the tensioner bracket (Tensor cod. 05.1, V07 M8X50 CIL x12); skip this step if the enclosure add-on is ordered — the tensioner is done after mounting the enclosure side panels (step 5.3.4)
When the chain needs shortening
Section titled “When the chain needs shortening”If the tensioner knob is fully tightened but the chain still jumps the pulley during fast moves (especially during lightning infill or fast travel):
- Power off the machine
- Release the tensioner knob completely
- Cut the cable ties holding the chain
- Remove exactly 6 chain links (approximately 1 cm shorter)
- Reconnect the chain ends
- Secure with new cable ties
- Re-engage the tensioner knob
- Test by hand-moving X end-to-end — chain should feel firm and not skip
Pulleys
Section titled “Pulleys”Drive pulleys
Section titled “Drive pulleys”- Attached directly to the stepper motor shaft
- Secured with grub screws (set screws) against the flat of the shaft
- Grub screws can back out over time — the pulley spins on the shaft instead of driving the belt
Checking for a loose pulley
Section titled “Checking for a loose pulley”- Power off the machine
- Mark the pulley and motor shaft with a pen
- Manually move the axis
- If the mark shifts (pulley rotates relative to shaft) → grub screw is loose
Fixing a loose pulley
Section titled “Fixing a loose pulley”- Loosen the grub screw
- Position the pulley against the shaft flat
- Apply blue threadlocker (medium strength) to the grub screw
- Tighten firmly
- Let threadlocker cure before use
Maintenance schedule
Section titled “Maintenance schedule”| Interval | Task |
|---|---|
| Monthly | Check belt tension by hand press |
| Monthly | Listen for clicking / clunking during XY moves |
| Every 6 months | Visually inspect belt teeth for wear or cracks |
| Every 6 months | Check pulley grub screws |
| Every year | Full mechanical inspection |