Motor pulley too loose Y
Hi all,
New Prusa i3 MK3S owner here
So I am at a loss now after I have finally received my MK3S and assembled it, took every step and made sure the results were exactly the same as in the manual.
But after turning it on (It' didn't explode, YAY!) and starting the self test I keep hanging on the issue that the Motor Pulley for the Y is too loose. I double checked all the screws on the pulley/motor and they are as tight as they go, I heightened the tension of the Y belt two turns, redid the test (holding the shaft and trying to move the carriage) and it seems the tension is good as I am unable to move the carriage. checked if the belt is parallel, which it is. Redid the self test and I still have the same problem... The printer moves the carriage without any issue, it goes towards the back correctly, then it goes towards the front correctly and seems to hit the front of the printer, then it goes back again to the middle and gives the error.
What am I doing wrong here?
RE: Motor pulley too loose Y
Common problem caused by improper assembly. The instructions should be more complete and clear.
Flat First: Drive gears must be tightened flat-first.
1) Start with both set screws fully loosened so the pulley is free to spin on the motor shaft.
2) Align one set screw dead center with the flat on the motor shaft, slowly tighten the screw until it fully contacts the flat surface.
3) Torque the flat set screw to spec.
4) Now tighten the jam set screw, and torque it to spec.
Once tightened, never touch the flat set screw unless the jam screw is first fully loosened.
Why Flat First? Set screws have flat ends. If you tighten the jam screw first the set screw on the shaft flat doesn't fully contact the shaft, only one small edge of the screw surface is biting. Reversing torques can easily shift the shaft to a position the flat screw no longer contacts the shaft. This lets the jam screw wriggle loose. And after a while, vibration loosens the screws until the gear is free to rotate.