PINDA probe, live Z calibration, Z-offset and temperature
Hi everyone.
TLDR version below.
I have run into something that many seem to have experienced, i.e. that when you change materials the Z-offset needs to be readjusted. By a lot.
Also, all attempts to print ABS would fail a few times, just to succeed at Nth attempt, not showing any reasonable consistency in failure reason beyond having to adjust Z-offset more and more with each print attempt. I suspected a firmware bug already (not saving Z-offset or similar).
Now, being an engineer, something in my head goes click, when you have to reduce the 0.15mm nozzle gap by 0.3mm (addotional Z-offset) to get an usable print. I mean, come on, negative space is a term in text layout, architecture, but not in mechanical engineering.
So I got thinking on that and figured out that it's not bed warping, nor the nozzle size change (both factors to consider, but definitely not 'worth' 0.3mm), but the temperature sensitivity pf the PINDA probe. The original initialization code heats up the bed first and then homes the axes and does the mesh init. Depending on how far the PINDA probe is from the bed, and what temperature the bed is set to, PINDA probe gets more or less hot.
So, I adjusted the init code as follows:
M115 U3.0.8 ; tell printer latest fw version
; M301 P22.1 I1.80 D68 ; set PID for nozzle - set proper values for your printer and uncomment the line, else just ignore it
M83 ; extruder relative mode
G28 W ; home all without mesh bed level
G0 Z80 Y-3 ; get head above bed to keep it cool, move the nozzle up front to make cleaning easier
M140 S[first_layer_bed_temperature] ; set bed temp
M104 S150 ; set extruder temp to 150C, cold enopugh to avoid ooze, but get some temp on it
M190 S[first_layer_bed_temperature] ; wait for bed temp
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
; G28 W ; home all without mesh bed level - rehome Y axis to accommodate for thermal expansion -> not necessary, mesh leveling does it too
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
So, in short: home axes, move Z to 80mm above the bed, heat up everything, only after the temperatures stabilize do a mesh leveling.
Result: instead of having to adjust offset of -0.272mm (good for PLA) to -0.550 (so ∆=280µm) for ABS now I have to adjust it only by about 50µm (to -0.300..320), which is by all means something thermal expansion can be responsible for.
TL;DR:
Pinda probe gets hot from the bed, influencing the readout. Raise print head when heating bed up to keep the probe cool and then use mesh leveling - results will be more reliable. Adjusted init code above.
Have fun,
Marek :geek:
Re: PINDA probe, live Z calibration, Z-offset and temperature
Just a notice.
If you do home all axes with cold nozzle and you got some debris on the nozzle, it will hit the bed really hard. Heat the nozzle at least to 170°C before homing Z.
Re: PINDA probe, live Z calibration, Z-offset and temperature
Just a notice.
If you do home all axes with cold nozzle and you got some debris on the nozzle, it will hit the bed really hard. Heat the nozzle at least to 170°C before homing Z.
True, I just have the habit of cleaning the nozzle manually, but the code for heating the extruder to 150°C can be advanced in the init code up to before homing...
M115 U3.0.8 ; tell printer latest fw version
; M301 P22.1 I1.80 D68 ; set PID for nozzle - set proper values for your printer and uncomment the line, else just ignore it
M83 ; extruder relative mode
M104 S150 ; set extruder temp to 150C, cold enough to avoid ooze, but get some temp on it
M109 S150 ; wait for extruder temp
G28 W ; home all without mesh bed level
G0 Z80 Y-3 ; get head above bed to keep it cool, move the nozzle up front to make cleaning easier
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M104 S[first_layer_temperature] ; set extruder temp
M109 S[first_layer_temperature] ; wait for extruder temp
; G28 W ; home all without mesh bed level - rehome Y axis to accommodate for thermal expansion -> not necessary, mesh leveling does it too
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
Re: PINDA probe, live Z calibration, Z-offset and temperature
And one more notice.
Depending on bed and hotend target temperatures, the heating may take quite a lot of time. During that time X and Y motors may go off (stand unpowered). If somebody touches the printer (X carriage or bed) after that and before the printer starts printing, the printer may lose home position.
Re: PINDA probe, live Z calibration, Z-offset and temperature
And one more notice.
Depending on bed and hotend target temperatures, the heating may take quite a lot of time. During that time X and Y motors may go off (stand unpowered). If somebody touches the printer (X carriage or bed) after that and before the printer starts printing, the printer may lose home position.
I'm pretty sure that the steppers remain under power during the heating phase of that script, will check tomorrow...
Else, just uncomment the line re-homing the axes.
Regards
Marek
Re: PINDA probe, live Z calibration, Z-offset and temperature
Marek, this is fantastic information, and it seems to make perfect sense. It explains why I've had so many issues on some days, but not on others.
Can you open an issue ticket in the GitHub repo for the firmware? This is something that should be fixed in firmware.
Re: PINDA probe, live Z calibration, Z-offset and temperature
Can you open an issue ticket in the GitHub repo for the firmware? This is something that should be fixed in firmware.
Done
Re: PINDA probe, live Z calibration, Z-offset and temperature
Can you open an issue ticket in the GitHub repo for the firmware? This is something that should be fixed in firmware.
Done
https://github.com/prusa3d/Prusa-Firmware/issues/16
Marek
Glorious. Fingers crossed.
Re: PINDA probe, live Z calibration, Z-offset and temperature
How about changing the end of print behaviour instead?
I modified the "End G Code" in Slic3r to:
G4 ; wait
M104 S0 ; turn off temperature
M140 S0 ; turn off heatbed
M107 ; turn off fan
G1 X125 Y200 Z200; lift extruder for cleaning
M84 ; disable motors
This lifts the extruder to the top middle, where it is easy to reach for cleaning, and gives me time to remove dangling bits of filament when it starts to move for the next pre-print calibration.
Re: PINDA probe, live Z calibration, Z-offset and temperature
This lifts the extruder to the top middle, where it is easy to reach for cleaning, and gives me time to remove dangling bits of filament when it starts to move for the next pre-print calibration.
I'm afraid you have missed the point. It is not the debris that we have the main problem about here. Moving to the top at the end won't help heating up the pinda probe at the start
Re: PINDA probe, live Z calibration, Z-offset and temperature
This lifts the extruder to the top middle, where it is easy to reach for cleaning, and gives me time to remove dangling bits of filament when it starts to move for the next pre-print calibration.
I'm afraid you have missed the point. It is not the debris that we are talking about here.
I can see why you think I missed the point, but I did not. 🙂
What I suggest is to lift the extruder at the end of a print. It achieves the same effect on PINDA probe temperature. Maybe better, because if you want to start the next print soon, then the probe will remain warmer if it is parked just above the bed.
Maybe it's best to include lifting of the extruder in both Start and End code, so that it still gets lifted even if a print was stopped before it finished and executed the End code.
Re: PINDA probe, live Z calibration, Z-offset and temperature
I can see why you think I missed the point, but I did not. 🙂
What I suggest is to lift the extruder at the end of a print. It achieves the same effect on PINDA probe temperature. Maybe better, because if you want to start the next print soon, then the probe will remain warmer if it is parked just above the bed.
It will help, but I think you need to change the start code anyway. Now when I think about it, I'm not sure what the most current default code is, I'd have to check, but I was under the impression that the default code homed all axes first... Or was it already my workaround for a yet different bug (the one in xyz calibration)?...
Guess I'll have to eat my hat after all 😀
Re: PINDA probe, live Z calibration, Z-offset and temperature
The current start code in Slic3r is this:
M115 U3.0.9 ; tell printer latest fw version
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
Re: PINDA probe, live Z calibration, Z-offset and temperature
The current start code in Slic3r is this:
M115 U3.0.9 ; tell printer latest fw version
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
Munch, munch munch... That's me eating my words 😉
Now, it'd be great if we could get a code like "rise Z to at least 80mm". It's possible to move Z relative by 80mm, but I'm not sure there's a check against max Z...
Re: PINDA probe, live Z calibration, Z-offset and temperature
Firmware allows Z to go to 210, which is 9mm higher than it can physically travel.
Therefore, the next action must be to home Z, otherwise a bed crash is possible...
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PINDA probe, live Z calibration, Z-offset and temperature
Firmware allows Z to go to 210, which is 9mm higher than it can physically travel.
Therefore, the next action must be to home Z, otherwise a bed crash is possible...
Peter
Well, by the way, the "calibrate xyz" fails to comply...
Re: PINDA probe, live Z calibration, Z-offset and temperature
Serious? There really is not much logic in that statement, biassed (note spelling) or not.
Yes, when you are manually raising the Z axis to the top for levelling, there are no checks.
Peter
P.S. Apologies; I have had a very bad day.
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PINDA probe, live Z calibration, Z-offset and temperature
Serious? There really is not much logic in that statement, biassed (note spelling) or not.
Yes, when you are manually raising the Z axis to the top for levelling, there are no checks.
Peter
P.S. Apologies; I have had a very bad day.
Well, if you wanted to vent off, you just did. Duly noted. Unless you are aiming at calling somebody an ass, you spell biased with one 's', at least my M-W does.
Yes, there's logic in that statement. There's also a hole in the lower-left corner of my i3 MK2 heatbed to prove that. The "Calibrate XYZ" sometimes assumes (two s and then one s) it has much more free travel than it really has, but never so if you home the axes manually first.
Honestly, considering the original posting is almost month and a half old and so is the bug report on github, and till now the only response to both is mocking my nickname, I do wonder what did I pay €300 more for (comparing to a Chinese clone).
Re: PINDA probe, live Z calibration, Z-offset and temperature
verb (used with object), biased, biasing or (especially British) biassed, biassing.
Yeah, OK, I'm a Brit... 😀
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: PINDA probe, live Z calibration, Z-offset and temperature
first time on this forum and I came looking for this very information. I just started using ABS for the first time and i was having the same issue with the Z height. I also had to adjust an extra ~.2mm when using ABS and then spent many hours playing around with the height adjust.
is the workaround in the first post still being used by people?