Yup! That’s exactly what mine was doing only towards the right front of the print bed! Your numbers look very odd, however. Seems like your print bed is warping upward in the middle, and dipping slightly lower on the left side compared to the right. Then somewhat leveling off on the back corners, while still remaining warped upward the the middle. Not sure what is going on here! I would start by adding paper shims to the front corners and see how the numbers change. Hopefully your bed isn’t warped too much that it is not correctable. The object is to bring all your numbers as close to zero as possible, and hope that the auto level does the rest. Did you do your first run fine tuning paper calibration cycle yet? If you have not done this it might help your auto-bed leveling to do this first! Are you using MatterControl?
Ok so I am using Repetier. Specifically slic3r in repetier.
I did the paper test to calibrate the x axis before the picture shown above. This is why its relatively symmetrical across the x.
I agree my numbers imply a convex bed plate but it says the same thing for the actual bed and the sitall bed I clip ontop of it. It seems odd that both would have the same warped geometry
Lastly I added paper shims to the front corners this morning and it seems like it is generally helping. Couple of issues though:
(1) First the amount of paper I have to use: I am at like 8 or 9 pieces between the magnets in some areas. so there might be a chance of instability if the thickness of the paper stack goes beyond the depth of the countersunk hole.
(2) The numbers seem to change: my suspicion is this is related to how the magnets seat themselves in their respective holes (aka crappily) but I am looking at ±0.1 at all corners after I lift and then re-seat the bed.
(3) Getting it to zero. Thats fine for any of the negative values. Just add shims. But for the positive values I cant subtract shims that arent there. Are these values all relative to some starting value or to some absolute machine value?
My goal right now is to just get the deviation as close to zero as possible, not the actual values. Anyway I ran another print this morning post shimming and it is much better. However with it more level now my z offset is incorrect. Rather than it being equally smooshed down in all areas like I want it is equally too far away from the bedplate in all areas. C’est la vie.
I’ll post an update tomorrow morning once I dial in the shimming more although any help (especially with the positive, high spots) is much appreciated.
Geoff
Your right the shim technique will not work on the positive values, but try running your fine tuning paper cycle again and possibly set your z-offset back to where it ought to be. See if this makes a difference. I think once you clip your sitall glass on top of your already warped print bed, it warps your sitall glass. All Glass is flexible after all, but only to a certain point before it snaps. Not sure how much trouble you want to go through to solve this, but you could try shimming your sitall glass to see if you could get it more level then your bed. You could just as easily buy another bed from Robo3D and hopefully you get a better one this time. Sorry you have to go through all this frustration, but we’ve all been there and it’s not easy. It’s the nature of the beast in this arena.
This is a very common problem. It isn’t due to warped glass, it relates to two things when your printer is probing the bed:
1) probing the centre of the bed causes the glass to bend giving a lower-than-it-should-be reading
2) when probing the left-hand side the x-carriage pivots on its rods only tripping the one microswitch also giving inaccurate readings
The upshot is to manually level the bed as people here have already discovered.
More info and some interesting solutions including IR probing here:
Thanks for the heads up. I’ll take a look at this asap. I’ve also scheduled a meeting with one of robo’s techs to get this sorted. I figured manual was the way to go when I kept getting varying results from the auto level.
Nice post you linked to! Not sure if this is what is going on in his case, as far as the warping issue though, because his glass is warped upward not downward. Unless there is a differential math thing I am overlooking. His numbers suggest his center point is much higher than the outer points not lower.