I just got my second mini up and running and I’m having problems with the first layer being uneven. After adjusting the Z offset, the left side of the bed squishes too much and on the right it’s barely on the bed at all.
Here’s the result of my G29
Recv: Eqn coefficients: a: -0.00706973 b: -0.00024144 d: -3.04036855
Recv: Mean of sampled points: -3.61746835
Recv:
Recv: Bed Height Topography:
Recv: +--- BACK --+
Recv: | |
Recv: L | (+) | R
Recv: E | | I
Recv: F | (-) N (+) | G
Recv: T | | H
Recv: | (-) | T
Recv: | |
Recv: O-- FRONT --+
Recv: (0,0)
Recv: +0.56859 -0.60916
Recv: +0.59084 -0.55028
Recv:
Recv:
Recv: Corrected Bed Height vs. Bed Topology:
Recv: +0.01834 +0.00000
Recv: +0.00003 +0.01832
Recv:
Recv:
Recv:
Recv: Bed Level Correction Matrix:
Recv: +0.999975 +0.000000 -0.007070
Recv: -0.000002 +1.000000 -0.000241
Recv: +0.007070 +0.000241 +0.999975
I’ve checked the X axis to make sure it’s level, and made sure all the leveling washers are tight. Any help would be greatly appreciated.
When I want to look at the G29 results, I use G29 V4 and I get the X,Y,Z coordinates of each corner as it is probed. Not being a mathematician, I’m more comfortable looking at those raw numbers than I am the number-crunched results. Did those values get reported and you didn’t post them or did they not get reported?
The test print looks good to me (ignoring the center square) and from the G29 V4 numbers, there is a definite tilt of the bed in the X dimension. Y looks good. I believe those numbers correlate with the symptoms you first reported.
I had an occasion on my mini 1 where 1 z axis leadscrew bound due to thick lithium grease and the printhead carriage got canted in relation to the bed as the other leadscrew kept moving. I cleaned the leadscrews and regreased, but they never realigned using the pre-print bed levelling routines. I manually moved back the z axis screw that had moved when the other one stuck, and it has worked fine since. I measured the leadscrews at 2 mm thread pitch, turning the screw counter clockwise (Viewed from the top) moves that side of the printhead axis down. Power to the printer must be off.
I always assumed the mini bed levelling test would adjust the z axis leadscrews, but that does not seem to be the case. My Taz 6 is the same. Can anyone expand on this, because this does not seem right.
There is no mechanism or means for either the Mini or the Taz to move either of the two Z-axis motor independently. They are simply wired in parallel. This means that barring mechanical problems, they should never get out of step with one-another… but in the face of mechanical issues, it also means that as you’ve observed, they require manual correction by a human.
The bed leveling is a mis-nomer – it doesn’t actually level the bed, what it does is measure the mis-alignment of the bed and apply a Z-axis correct factor to compensate for the non-level bed as the X and Y axis moves about.
I’ve checked and adjusted the lead screws, it’s one of the first things I looked at.
Like @mwester mentioned, the actual leveling for printing is all done via software, and that’s why I’m stumped. I vaguely remember reading somewhere that the max it can compensate is 1mm. It looks like I’m over that so maybe that’s why I’m having problems?
I print some production parts that go out to the edge of the printing area (print not bed area) and the skirt won’t even stick on the right side but is super squished on the left. I printed a benchy and it was perfect so the center is OK.
The one thing I can think of is I reprinted the bed bearing holders to use LM8UU bearings, and I’m blaming myself for maybe making a mistake there. I ordered the factory bearing and printed the Mini 2 bearing holders which only uses 3 vs 4.
