Is my printbed upside down?

Charly3

Linear, bilinear and ubl leveling - the result is the same. The left side of the bed shows negative values in measuring points, the right side positive. So what I´d expect is that the filament on left side is printed slightly higher more round and on the right side it is pressed a little bit more during initial layer. But what happens is exact the opposite. Left side the filament is pressed to the bed, while right side string is round and doesn´t stick to the bed. Meanwhile I guess that somehow the measured values are inverted. Any Idea to flip it? All I could find in configuration.h does invert the real motion of head and bed - not only the measured values. Any Idea where to invert?

Reg. Charly

PS. Any experiences with g26 test print? It jerks and shakes my printhead  and extruder that normaly moves fluently thanks of 2208 drivers.

Der_Muck

What do you use, BL touch or IR probe?

Laser8302

I am in the same situation. For instance the left side is higher than the right,  but  the right is too close and almost grinds the nozzle and the left is too far away.

Using a BL-touch that is mounted 40mm in front of the nozzle and directly in line on the X axis.
Marlin 1.1.9C

Since my TMC 2208 are still in standalone mode I might try going back to 1.1.8C just to see if its firmware based.

I've also been playing around with leveling the gantry by twisting the Z lead screws slightly. I would think even with a slanted gantry though that with auto bed leveling it would compensate to some degree? Isn't that the point of bed leveling?

Laser8302

I *think* I found my problem.

I didn't follow the video where they used a G92 command instead of setting the Z offset using M851.

For example:
I measured my nozzle to bed distance = -3.5mm when it says Z=0 for my probe.
So I did a M851 Z-3.5
I think the problem with this is Marlin 1.1.9 expects the BED to move instead of the GANTRY. So when the grid says "+0.2" it moves the gantry DOWN 0.2mm crashing into the bed.

I've checked this multiple times. When my gantry is "tilted" by adjusting the Z-screws the lower side reports HIGHER instead of LOWER.

So I'm going to try and add this to my start G-code:
G0 Z10 ;Move gantry up to 10mm
G92 Z13.50 ;Tell the FW it's actually at 10+3.5=13.50mm

I did some extensive reading on the subject. It would be better if you have a Z-probe offset in your configuration.h or use the M92 command. I think. I'm going to try this tonight and remove my Z-offset.

Edit: I went the wrong way with the G92 command... Fixed it.

Laser8302

More reading, more insight.

I'm going to adjust my Z-probe offset in firmware even though many people say you only need M851 ZX.XX to set the offset.

I'm also making sure to add G29 L1, G29 A and G29 J to my start script. I used to use M420 S1, that just activates bed leveling, it doesn't load a mesh...

So G29 L1 = Load mesh
G29 A = Activate/use the mesh
G29 J = Probe 3 points on the bed to see if there's a "tilt" to the mesh since it was recorded.

I think G29 J before printing will be key to fixing my problem, as well as making sure the mesh is loaded with G29 L1.

Samuel Pinches

If you save the mesh to the eeprom (M500) it should in theory be autoloaded at boot. So then you only need the M420 S1? Not sure.

Laser8302

I've struggled more with 1st layer problems than ever on this printer.
I've lubed the Z lead screws and the rails too. I took a pair of calipers to the top rod and the top of the chassis so that my X-axis is within 0.05mm of level then I've tried to level my bed. Because of the touch probe and Z safe homing I check the center Z-height and adjust up/down first with a 0.2mm feeler gauge and do a G92 Z0 then check the heights of each corner. I just haven't had time to dial it in fully yet.

I got the printer 2nd hand. I'm thinking about ordering a new heat bed and a piece of borosilicate glass. The "diamond glass" is stuck with adheasive instead of clips.

Laser8302

First, I want to apologize for hijacking this thread.

Edit: No success... just a random fluke that it worked...

You can follow my struggles here