• Attach mounts to the frame loosely, mount drive shafts and idlers, then tighten.
  • Align so that idlers are 1mm from the gantry-frame.
  • Center stepper motor in a way to evenly distribute overlap of the drive shaft couplings.
  • Belt tension is critical for good performance. Tension by pulling at the base of the idler screw with the shaft of a thin screw drive. Use about the force you can easily assert with your wrist only. When belt is under tension tighten idler screw.
  • Differential alighnment of the y-cart: Adjust by leaving one shaft coupling open, push y-cart all the way back, then tighten.


  • Idler T-slot nuts are of the "preassembly" kind. This makes it easier to adjust the belt tension.
  • Shaft mounts and motor mount are all perfectly vertical.
  • Y-cart is perpendicular to the frame.
  • Belts do not climb pully teeth when moving slowely (avoid fast-pushing the gantry).
  • Y-cart is horizontally constrained. Horizontal rollers have no/minimized spacing on both sides along entire range of motion (Rails may have to be adjusted to be perfectly parallel).
  • All rollers are touching the rail without excerting exessive stress.
  • Top rollers of y-cart are all on the same level (avoid twisting the cart).