Height map has a substantial Z offset error with mesh

Origami

Hi All,

I recently upgraded my CR10S with a duet 2 ethernet and added the IR abl probe for bed leveling, it worked flawlessly for about a month and since yesterday my mesh is suddenly lifted 0.25 mm or higher than usual and it is messing up my first layer.

I have tried to use z babystepping to compensate but it need to go up to like -0.8mm instead of less than -0.2mm before.
I'm also getting the error message:

G29
Warning: the height map has a substantial Z offset. Suggest use Z-probe to establish Z=0 datum, then re-probe the mesh.
30 points probed, min error 0.074, max error 0.231, mean 0.146, deviation 0.044
Height map saved to file heightmap.csv

Looked up what it means and I have checked that I am using G30 to home Z before G29 but still getting this problem.

My mesh before:
alt text

Mesh now:
alt text

I did recently upgrade the firmware to 2.03 but it did work for a few days after that and I havent made any changes to firmware since. I have now installed 2.04RC1 and still have the same issue.

Phaedrux

Please post your config.g and homing files.

Origami

4_1563933106610_homez.g

3_1563933106610_homey.g

2_1563933106610_homex.g

1_1563933106609_homeall.g

0_1563933106609_config.g

Phaedrux

It doesn't look like there is any weirdness with your homing files.
Do you also have a bed.g macro?
What does your slicer start gcode look like? Does it call G32?
When are you running G29 or loading the heightmap?

I would suggest redefining your trigger height and re-running mesh compensation with 2.03.

https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe

Origami

This is my starting gcode:

M572 D0 S0.2 ;Pressure Advance
M82 ;absolute extrusion mode
G90; Use logical positioning
G92 E0 ;Nulls out the extruder
G28; Homes the nozzle on x,y,z
G28 Z; Homes the z axis again
G30; Home z again with probe
G29 S1; load last bed mesh from memory
G4 S15; waits 15 seconds for the heaters to recover

G1 Z5 ;moves up a bit
G1 X295 Y30 F2700 ;moves over the front right corner.
G1 Z0.3 F100; height of small blob
M106 S255 ;turns fan on full
G1 E20 F200;extrudes a small blob
G4 P4000; Waits 4 seconds to the blob to cool a bit
G1 Z0.5 ;moves up a bit
G4 P5000; Waits 5 seconds to leaker to flow and cool a bit
G1 Z7 F100; Pull out of the blob a bit
G4 P5000 ; used for cooling down the stringing
M106 S0 ;turns fan off
G92 E0 ;Nulls out the extruder
M83 ;relative extrusion mode

I manually do the mesh with the web gui once in a while and the starting gcode just does G29 S1 to load it.

Phaedrux

That looks ok too.

As I said above, clear your heightmap, remeasure your trigger height, and then redo the G29 with 2.03. See if the problem persists.

Origami

EDIT: also i found the bed.g as well here it is:
0_1563938574407_bed.g

I did the Calibrate the Z probe trigger height in the link you provided, also deleted the heightmap file before proceding and im still getting the exact problem.

alt text

Veti

your bed and hotends have the default B4138 value.
this is most likely incorrect for your thermistor and will report the wrong temperature.

Origami

@veti hmm what should I set it to? I have the stock cr10s thermistor for both hotend and bed

Veti

according to the marlin config
https://github.com/MarlinFirmware/Marlin/blob/bugfix-2.0.x/config/examples/Creality/CR-10S/Configuration.h

the hotend is a epcos 100k and the bed is a semitec 104GT-2, both can be selected in the duet configurator.

Origami

@veti this may sound stupid but how do i select it in the duet configurator lol... is it the rrf config tool? It just asks me to type in the b value there are no preset selections.

alt text

I have found the Semitec b value in the wiki here but Epcos 100k have 3 different model so not sure which one I should be using...
https://reprap.org/wiki/Thermistor

Veti

click into the beta field and the selector will open

Origami

@veti OH now i feel dumb xD thanks for the tip there, got my bed at 4267 and nozzle at 4092 now

I looked up datasheet for both thermistor and used that instead of the preset since it seem to be incorrect as the EPCOS was only 10k ohm on the rrf.

Veti

you are correct. that is a mistake in the configurator. it is supposed to be 100k and 4092 B
see
https://github.com/MarlinFirmware/Marlin/blob/bugfix-2.0.x/Marlin/src/module/thermistor/thermistor_1.h

Origami

Back on topic tho... I'm running a new bed mesh now with the bed heated up to 60c... I'm sure the temp will be more accurate than before now.

but mesh has no luck, bed is still floating in midair on the mesh for some reason..

Veti

but it does work if you probe before every print?

Origami

@veti that will have same result, basically my mesh is like 0.7 mm higher than what its supposed to be, I can use the Z baby stepping in web gui to lower the nozzle to around -0.95 mm and it'll print OK. Before the lowest I have used is like -0.25 mm

Veti

i am guessing the you are doing the homing with the hotend and bed turned on.
did you create the heighmap under the same conditions?

Origami

@veti yes everytime mesh is done it is at printing temp

gueee78

@dc42 do you have any idea what could cause that behavior. I tried to help him find the issue but since z-homing with the mini IR works flawlessly I can't think of what it actually is.
it seems like it just adds a certain offset value to the probe values at some point for no reason.
as if z0 gets redefined after initial z homing.