Stiff y-axis
Hi,
I've just built my MK3s this week (first printer) and an hour into a print, my Y axis skipped almost 4mm (1-2 belt notch?) and continued printing misaligned. There was also a clicking noise when the hot bed moved passed 2 precise Y positions :
(the clicking went away after unpluging and moving the bed by hand a bit)
My y axis feels very stiff to move when the power is off. I need to put a lot of pressure to push the hot bed (feels like 10 times more than the X axis)
The belt also feels stiff to bend, stiffer then the X axis. Self-test is reporting that the tension is X=280 and Y=200. I tried loosening the Y belt until it was sagging and the tension is still registering 219 ! I can't get the number any higher without skipping and failing selftest.
I removed the belt to test if the bearings were the cause and the hot plate seems to move freely on the linear rails. I greased and realinged the rails, but it feels no different.
I'm out of ideas to troubleshoot this issue. The motor looks fine, nothing is rubbing on its moving parts, but it is stiff to turn by hand.
What should I try next ?
RE: Stiff y-axis
does the motor rotate freely when the belt is off? some people get the hub of the Y motor pulley rubbing on the casing causing excess friction
did you do a re calibration when the belt was loose?
the tension values only get updated when the calibration is re run...
Is the idler bearing free to rotate? it is possible to overtighten the support bolt and jam the idler
could the idler bearing have collapsed? I had the X idler bearing collapse and that caused a clicking noise and excess resistance.
if the heatbed cable bundle free to move backwards and forwards?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Stiff y-axis
does the motor rotate freely when the belt is off? some people get the hub of the Y motor pulley rubbing on the casing causing excess friction
It "does" ... I mean it's not rubbing on anything, but I can hardly rotate (one-handed) :
Should it be so hard to turn ?
did you do a re calibration when the belt was loose?
Do you mean I have to rerun "Calibrate XYZ" ? No I didn't yet, I only ran the "Self test" and I saw that it did update the "Belt tension" numbers a bit in the "Support" menu
the tension values only get updated when the calibration is re run...
Is the idler bearing free to rotate? it is possible to overtighten the support bolt and jam the idler
It's running freely
could the idler bearing have collapsed? I had the X idler bearing collapse and that caused a clicking noise and excess resistance.
I don't believe it collapsed, they seem to turn just fine and noiselessly.
if the heatbed cable bundle free to move backwards and forwards?
Cables are moving freely too.
regards Joan
Thanks again
RE: Stiff y-axis
Contact support. Eshop above, log in, click Chat button.
Link them your video.
This is assuming your printer was powered off...
RE: Stiff y-axis
I think the problem is in the motor,
That looks very stiff.
was the power off at the time you were trying to move the motor spindle?
Is there any chance the wires are squashed somewhere as that can make the motor hard to turn.
as a complete aside, I believe you have the pulley on back to front... 
the hub should be towards the motor not towards the end of the shaft
It probably won't affect the current problem.
If the motor is still stiff to turn with the power off and having checked the wires are not squashed anywhere, try disconnecting the plug, from the einsy socket and then try rotating the motor again...
If the motor is still stiff, try loosening the case screws at the cable end of the motor and see if that loosens the motor up... (don't take the motor apart... it might invalidate your warantee.)
compare the force needed to rotate the X axis motor with the force needed to rotate the Y axis motor, if the Y axis motor is considerably harder, I would suggest that you contact the Prusa helpdesk using echat, on the eshop page... ( they may be busy due to the prusa mini delays and the black friday queries...) but I have always found them helpful.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK