Bed level skewed  

Re: Bed level skewed

i would say first look your frame over for any obvious signs that something is no longer level. if a nut got loose attaching the Y axis to the frame and sank down type of thing. make sure the printer is on a hard level base. I like to use a polished large flat floor tile made of man made type stone so it is very flat and level. that will keep all the legs level in case one of yours is sinking down. gives you a chance to also see if your Y axis is sitting level where one leg isn't lifting. with everything level. run XYZ cal again and see if things changed, like your skew suddenly improved.

that rules out frame issues and you can get to the bed.

run some more Z-level calibrations and find the low spots where the bed level adjustment just isn't enough find the nearest mount for the bed and you may need to install a shim to compensate.

Prusa built my MK3 and the left side of my bed was .5mm higher then the right side. I suspect the double Y axis bearings on that side were not seated correctly, but rather then take the entire machine apart i installed .5mm shims on the right side i ran be visualizer software to generate a map of the high and low spots on my bed and it was still terrible but usable. it might be impossible to come close to perfect without a ton of work and shimming. thus another option is compensate with a lower live-z and increased measurement for elephant foot compensation.

start with making sure your printer is sitting as perfectly as possible then start making adjustments.

i have personally found tables sag and cause all kinds of issues skewing the frame.

in addition to the floor tile i put a piece of foundation foam underneath the tile. that acts as a vibration/shock/level compensation for the surface then i place the level floor tile on top of the foam giving a very true surface to start from.

quick picture of the table which i tried to level, foam then a level floor tile as the base for the printer frame to sit on

Re: Bed level skewed

Calibration reports that everything is good. I have run it 3 times.

The pinda probe seems to be working as it scans the 9 points, at which point I thought the mesh bed levelling was supposed to even out any discrepancies between those 9 point mathematically. This does not seem to be happening.

Shimming seems unnecessary, as this was working perfectly well for the past few months.. no shims were necessary then.

I have it sitting on a epicurian cutting board, on a mahogany table.. it is well placed.

Re: Bed level skewed

Loosen off the PINDA mounting and re-install it. Maybe it hit an obstacle and somehow got nudged out of true. Also use some sewing machine oil or 3 in 1 on the threaded rods and smooth rods to ensure there is not a dirty patch that is grabbing just enough to skew your results. Finally, slacken off the four retaining screws on the bed and retighten 1/4 turn past finger tight.

Just do one of these at a time and test. That way you will know which one solves the problem and can report back for other's benefit.

Re: Bed level skewed

epicurian cutting board can warp...

however lets say the bed warped itself from heat cycling and pulling prints off the bed.
mesh level is only good to 50um in any direction which is .05MM you have to be pretty level already.

this is where shimming can come into play. if no matter what everything looks right but you have a low area then you have to shim.

now you can also check your Z axis make sure nothing has shifted and the Threaded rods are centered and that the X axis isn't getting skewed on one side. on the bed as william suggested open the bed bolts to the frame and re-tighten to see if stress is released.

Re: Bed level skewed

Thank you for this post. It gives me some ideas and insight on how to approach my newest printer problems.