Bed Level Correction/Calibration Issues
I have been having problems with getting my bed level calibrated well. I have been using the Hyperfine Firmware for the MK2S and it can only help so much. The stock firmware is woefully inadequate for helping with correcting these issues because of how the bed level correction points affect the other points when adjusted.
I have problems in areas that do not seem to be fully affected by the 8 side calibration points (there seem to be dips and hills between the points that when corrected for using the bed level correction cause problems with the rest of the bed).
I do not think the problem is actually with the bed, but rather how the PINDA reads the embedded cal points. I have tried raising/lowering the PINDA with no variance in the first layer quality after recalibrating z to the new PINDA height.
I have disassembled the printer and reassembled to try and ensure proper perpendicular axes and I get the "congratulations axes are perpendicular" message when I do a XYZ Cal. My current skew is .02 degrees.
If anyone has any tips or other suggestions for me to try I would be grateful.
Below is the result of a G80 V10 and G81 in Pronterface:
>>>g80 v10
SENDING:G80 V10
echo:Enqueing to the front: "G28 W0"
echo:busy: processing
echo:busy: processing
No clamping for first calibration point.
Z jitter data from Z cal. valid.
0: no xy clamping
X: 12.00000
Y: -2.00000
mesh bed leveling: 0.15667
Bed leveling, point: 1, calibration z: 0.69667
1: no xy clamping
echo:busy: processing
X: 114.00000
Y: -2.00000
mesh bed leveling: 0.73500
Bed leveling, point: 2, calibration z: 1.35667
2: no xy clamping
echo:busy: processing
X: 215.00000
Y: -2.00000
mesh bed leveling: 1.34000
Bed leveling, point: 3, calibration z: 1.24667
3: no xy clamping
echo:busy: processing
X: 215.00000
Y: 96.00000
mesh bed leveling: 1.25250
Bed leveling, point: 4, calibration z: 0.82667
4: no xy clamping
echo:busy: processing
X: 114.00000
Y: 96.00000
mesh bed leveling: 0.90083
Bed leveling, point: 5, calibration z: 0.51667
5: no xy clamping
echo:busy: processing
X: 12.00000
Y: 96.00000
mesh bed leveling: 0.55750
Bed leveling, point: 6, calibration z: 0.39667
6: no xy clamping
echo:busy: processing
X: 12.00000
Y: 194.00000
mesh bed leveling: 0.40333
Bed leveling, point: 7, calibration z: 0.76667
7: no xy clamping
echo:busy: processing
X: 114.00000
Y: 194.00000
mesh bed leveling: 0.81250
Bed leveling, point: 8, calibration z: 1.24667
8: no xy clamping
echo:busy: processing
X: 215.00000
Y: 194.00000
mesh bed leveling: 1.17917
clean up finished
babystep applied
Bed correction data valid
Bed leveling correction finished
Upsample finished
Mesh bed leveling activated
echo:busy: processing
echo:busy: processing
echo:busy: processing
Go home finished
>>>g81
SENDING:G81
Num X,Y: 7,7
Z search height: 5
Measured points:
0.40333 0.54444 0.68083 0.81250 0.93944 1.06167 1.17917
0.51639 0.63676 0.75469 0.87019 0.98324 1.09386 1.20204
0.56778 0.67895 0.78957 0.89963 1.00914 1.11809 1.22648
0.55750 0.67102 0.78546 0.90083 1.01713 1.13435 1.25250
0.48556 0.61296 0.74238 0.87380 1.00722 1.14265 1.28009
0.35194 0.50478 0.66031 0.81852 0.97941 1.14299 1.30926
0.15667 0.34648 0.53926 0.73500 0.93370 1.13537 1.34000
Re: Bed Level Correction/Calibration Issues
There are by design only 9 points which can be calibrated. If your bed contains bumps or hollows between those points, there is very little you can do to correct for them in calibrations.
All you can do is to get decent 20mm square printed at or near to the calibration points and the rest is assumed within firmware.
Then it's up to you to get your first layer adhering to the bed as best you can. You could set the first layer to 0.25mm, ensure that the bed is as clean as possible and increase the bed temp to 65 degrees (PLA). You could try to loosen the screws holding the bed, heat the bed and tighten the screws or you could get a new bed without the bumps and hollows.
But no matter what you do, the bed will never be perfectly flat.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Bed Level Correction/Calibration Issues
Yeah, I am coming to realize that the first layer of my prints will be ugly even though they are fully functional and stick to the bed well. I have been able to get some great prints done, but I am a perfectionist and its going to nag at me until I can figure out how to correct it.
I will have to deal with it and post process where required until I can stop being lazy and implement the solution below.
My current solution is going to be to take some really fine grit sandpaper (800-1500 grit) and slowly wear away the high spots to even them out with the lowest point on my bed which seems to be southeast of center between the 4 calibration points in that quadrant.
I also found out that the 4 corners of the y-axis frame are not fully correct from the factory either. I'm going to print them myself to see if I can get better level for where the smooth rods rest in the y-axis corners.
Re: Bed Level Correction/Calibration Issues
Just a quick update on progress.
I printed the Y corner Brackets and replaced the ones that shipped with my printer and this corrected part of the problem I was having. The left to right slant is not as pronounced (only slightly corrected with the new brackets) but still there. Everything is as level as I can get it... still have a skew angle of .02 degrees for X/Y axes so no problems there.
The problem is definitely either the bed itself or the PEI sheet. Since the PINDA readings didn't vary much from before/after the new brackets, the problem seems to be related to the calibration points themselves and how the PINDA is sensing them.
Will contact prusa support to see what they say, but I'm not hopeful they will do anything about it.
Re: Bed Level Correction/Calibration Issues
There's no reason why the probe values would change much. It's still triggering at thereabouts the same height - you can't change the probe sensitivity for different points. Go to "Live Chat" on the shop pages and give them a link to this thread.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…