Slanted Print
I just built my Original Prusa i3 MK2 and ran all of the calibrations. XYZ results stated "OK - Congratulations". I printed the Prusa logo and everything looked ok, i think, and I moved on to the gears. When it was finished, I noticed that the entire unit slanted from left to right and when I placed a right angle against it, it was clearly leaning away from the right angle. The gears move great in one direction and when reversed, they get to a point and pop but keep turning. I placed the right angle on my bed and the extruder motor is not flush against the right angle either. Is this a matter of my bed not being level from left to right and if so, how should I adjust it?
Re: Slanted Print
💡
the x/y/z calibration routine only could check whether x and y are perpendicular and measure the "height" of the calibration points in z-direction (for meshbed leveling).
but it can not check if the assembly in z direction is perpendicular !
you may have noticed that the calibration result was: "XYZ calibration ok. X/Y axes are perpendicular. Congratulations!", there was nothing mentioned about the z axis 😉 .
➡ make sure that the threaded 10mm rods of the y-axis assembly sit completely down inside the notches of the z-frame, that the 8mm rods for the bearings "snapped" into the y-corner parts and that the zip-tie fixed bearings sit inside the notches of the y-carriage !
this should fix the problem
dem inscheniör is' nix zu schwör...
Re: Slanted Print
Leaning prints could also be caused by problems with movement along said axis. See here for more details and things to check:
https://all3dp.com/common-3d-printing-problems-3d-printer-troubleshooting-guide/#Leaning
+ check if the axis moves freely & smoothly when the printer is powered off / belt is unhooked
Re: Slanted Print
RESOLVED!!
Thanks for your responses, they helped me go through the machine and look for issues where you mentioned. I found two problems and fixed them both, now it prints great! The first is that the center screws that connect the belt keeper to the bed had not fully engaged and there was a hump or bow in the bed. I was able to take both screws out and while holding the bed flat, screw them back in. The other issue and probably the biggest one is that the pulley on the X axis was out on the shaft too far and the belt was rubbing against the ABS part. You can see black dust from the belt in this picture. Thanks again for your help!
Re: Slanted Print
... You can see black dust from the belt in this picture...
would have been hard to notice if you've ordered your kit with black abs parts instead of the orange ones 
dem inscheniör is' nix zu schwör...
RE: Slanted Print
Just posting to say I had the same problem as the OP and it was the exact same issue: X belt was rubbing on the housing so I had to adjust the pulley to sit farther back on the stepper shaft.
Thanks for posting this! I didn't build this machine so it might've taken me a while to figure it out otherwise 😎