After replacing my print bed bearings, I couldn’t find any instructions on how to correctly set the preload on the Creality Hi. After experimenting, this procedure worked and stopped the binding/squealing. Posting it here to help others.
How to set preload on the Creality Hi printer.
Locating the adjustment screws
Under the removable build plate on the mid-left side of the bed, there are small oval rubber caps.
Remove the caps. Under each cap are two screws:
Left screw: Preload adjustment screw (closest to the spring)
Right screw: Bearing mounting screws
Procedure-
- Loosen both bearings & preload screws. (This side needs to float for alignment.)
- Disable / unlock the stepper motors in the printer settings.
- Heat the bed to operating temperature.
- Move the bed slowly by hand. (This allows the rollers to self-align.) (Make sure to move the bed slowly so the stepper motor doesn’t generate back-EMF into the control board.)
- Set the preload. (Use the screw closest to the spring. Far left).
- Tighten the preload bearings (These screws tighten by turning counter clockwise)
- Let the bed cool.
- Do a final snug on the bearings to lock in the adjustment. (Snug- Do Not over tighten)
This allows the system to align under real operating conditions instead of forcing the bearings into a bind.