a simple fix for firmware: 5.1.2+ without downgrade to 5.0.0
because of the latest firmware's toleration issues there is an error pops thru y axis calibration if you already didn't shorten all your y axis rods and 3030s' :P or downgrade to 5.0.0
just put the rings to the two ends of the left rod (double bearing side) and then calibrate.
The author marked this model as their own original creation.