Bed Leveling seems to change between prints/slicers  

Re: Bed Leveling seems to change between prints/slicers

What firmware are you using? i had that problem with 3.0.10 but I think 3.0.11 fixed it.

Re: Bed Leveling seems to change between prints/slicers

1) Make sure PINDA sensor is secure and not able to move.
2) People have reported a correlation between un-reliable bed leveling if bed and head are heated at a low Z value.
a) The solution to this is to start you print (e.g. the heat up) with the head raised up a bit off the bed.

Let us know if these help.

Re: Bed Leveling seems to change between prints/slicers

Same case for me.
Printer continues showing Z eight is not fixed, and I used all callibrations tools...

Every start print move Z manually and its affect to the model base.

Re: Bed Leveling seems to change between prints/slicers

This seems like the same issue as I described in Different live Z adjustments for different materials.

I managed to isolate it down to different responses of PINDA in different temperatures. Solution that worked for me (following cory.w's suggestion):

1. Move PINDA probe to be 1.6mm above nozzle (it was at 0.8mm in my original assembly).
2. Disable temperature calibration.
3. Change start g-code to raise head above bed to prevent PINDA from heating up:

M115 U3.0.11 ; tell printer latest fw version
G28 W ; home all without mesh bed level
G1 Z60 ; get head above bed to keep it cool
M83 ; extruder relative mode
M104 S170 ; heat up extruder to 170'C
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
G28 W ; home all without mesh bed leveling
G80 ; mesh bed leveling
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line

My findings:

1. Mesh bed leveling has to be done on bed in operating temperature, at is has high thermal expansion coefficient (36e-6/K, ~0,01728mm between room temperature and 100'C).
2. PINDA at 0.8mm above nozzle gets way hotter during print than at 1.6mm; thermal radiation has inverse-square coefficient.
3. Having pinda at 60mm above bed when it's heating up prevents it from (significantly) heating from bed.
3a. While firmware 3.0.11 has thermal calibration to combat just that, it was not working reliably for me. I prefer not to risk nozzle-bed collisions.
4. Initially heating extruder to 170'C is hot enough to ensure that any ooze left from previous activity will be soft enough to bend out of the way during mesh bed leveling, and not hot enough to produce new ooze.

I still get a wrong response if I cancel a print few minutes in and re-start before PINDA cools down to ambient again, but that is relatively rare (only if I mess up g-code file some way 🙂 ). Besides that, no live-z adjustments was required since.

HTH!

Re: Bed Leveling seems to change between prints/slicers

So I have made some progress on this issue.

So far it seems that using some modified Start/end parameters for Cura has made it more consistent. Basically it raises the hotend up above the heatbed about 100mm, then heats the bed, does the mesh bed level, and prints. This works about 90% of the time, with diminishing results once I start rapidly printing and not waiting for full cooldown.

However, now my issue is the first layer looking perfect while printing, but the bottom overlapping too much and giving a poor bottom finish despite being smooth. Anyone have an example of a perfect bottom layer finish on a MK2S I can compare with?

Re: Bed Leveling seems to change between prints/slicers

When starts, auto bed mesh levelling put the nozzle better close than start to print.
When the auto cleaning nozzle begins is time to run to Z Adjust before print... And every time values it plus. (Ex: now shows -0.2140)

Other issue is when I start Prusa, show message "This machine is not... " But all test are OK.

Re: Bed Leveling seems to change between prints/slicers

3. Change start g-code to raise head above bed to prevent PINDA from heating up:

M115 U3.0.11 ; tell printer latest fw version
G28 W ; home all without mesh bed level
G1 Z60 ; get head above bed to keep it cool
M83 ; extruder relative mode
M104 S170 ; heat up extruder to 170'C
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
G28 W ; home all without mesh bed leveling
G80 ; mesh bed leveling
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line

I'm not sure if that code was syntactically incorrect when you wrote it, or if the marco names and syntax have changed by the current Cura 3.0.4, but it's now {} instead of [] and material_bed_temperature_layer_0.

Here's what I've worked up based on your sequence. I've tested it and it works as designed, although we'll see if this long-term fixes my print-to-print first layer variability.

; New code for Cura

M104 S{material_print_temperature_layer_0} ; set extruder temp
G92 E0.0 ; reset extruder distance position
G1 Y-3.0 F1000.0 ; go outside print area
M109 S{material_print_temperature_layer_0} ; wait for extruder temp
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E21.5 F1000.0 ; intro line
G92 E0.0 ; reset extruder distance position

Re: Bed Leveling seems to change between prints/slicers

Does the pinda reach some kind of equilibrium when heated as well? Last night I was able to do back-to-back-to-back prints of some calibration squares with good consistency. I just printed another set of squares today only to find that my live Z is much too low and needs to be raised.

In the same vein, should bed fine tuning (ie. G80 L# R# F# B#) remain the same or is that also influenced by heat? Wondering if I need to go back and adjust my G80 values. [Edit] I kind of answered my own question for this one. Waited until my bed and nozzle had cooled down fully and re-ran the calibration print and adjusted my live Z accordingly. Bed seems about as level as I had it yesterday, the left side value seems slightly lower than it should be but overall still very good. Interestingly I had to drop my live Z from -0.315 to -0.265, maybe even less, but beyond that it looks consistent.

Re: Bed Leveling seems to change between prints/slicers

I have just done prints in PETG, TPU and PLA using KISS , prusa control and slic3r without changing z level adjustment.

the only special treatment was the application of forehead grease to the build plate before the TPU Prints to prevent over aggressive bonding to the build plate.

I normally use talcum powder for this purpose with tpu, but the grandchildren used my powder up, and didn't let me know...

as a matter of course I ensure the pinda is above z 60mm before heating the bed at the start of my prints.

regards Joan