Different live Z adjustments for different materials.
Forgive a newbie question, my Prusa Mk2S is my first 3d printer.
For two days I was printing with PLA. My "live Z adjustemenet" value to properly stick to hotplate was -0.847mm (that gave first layer thickness of 0.15mm).
Today I tried to print with ABS. Overall I'm very suprised with gread print quality, but "live Z adjustement" to get filament to hotplate is now -1.555mm. That's a lot of difference. Is this expected? Will I have to recalibrate Z everytime I change filament?
Re: Different live Z adjustments for different materials.
I have similar results, even with different colors of the same type/brand filament. I started writing down live Z for each. Also, each one has slightly adjusted 9 point tweaks for the hyperfine leveling thread.
Not sure if the varying z heights is normal though.
Re: Different live Z adjustments for different materials.
Well now I just don't get it. I just started another ABS print, and now I had to increase Z to -1.630, and this is the very same spool. This seems to be a lot of difference. Why is this happening? While increasing -Z seems safe, I'm worried that at a point I will have a hotend-heatbed collision.
Re: Different live Z adjustments for different materials.
Do you have your probe close to the bed during heat? There are 2 possibilities here.
1. Your current settings has your nozzle and probe near bed during heatup, which in turn, heats up the probe and causes variations. Solution, change your start script to have probe above bed at at least Z 70 or so to avoid heatup, then it will run G80 which checks z level before each print.
2. You may be using temp calibration to compensate for probe heatup, but the calibration may of happened at PLA temps and now that you are using ABS, temps are higher and causing variation.
Finally, with Z levels over -.700 or so, you should probably adjust your probe to be more sensitive to get your z levels down to around -.700 or lower.
Re: Different live Z adjustments for different materials.
I am using temperature calibration which I have re-done just prior to printing ABS. However, as far as I can tell, calibration uses heatbed to head up PINDA for 2 minutes with 50/60/70/80/90/100'C; this should be material-independent, no?
My PINDA is right now ~1mm above hotend. Should i lower it?
Re: Different live Z adjustments for different materials.
What slicer do you use, will it let you modify start code?
My suggestion would be to:
1.Disable temp calibration
2. Lower Pinda probe so its about as far as a credit card (I used actual card to measure this.
3. Run full calibration again
4. Use Jeffs Live Z Calibration Method https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981.html#p34724
5. Perform Hyperfine leveling (This one REALLY helped me out) https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/hyperfine-bed-leveling--t4330.html#p34730
6. Alter start Gcode to warm up bed while probe is away.
(My Current Start GCode)
M115 U3.0.11 ; use the latest firmware version
M301 P26.54 I2.05 D85.89 ; PID tune for exact printing temp
M304 P62.87 I2.50 D395.26; PID Bed Tune for bed temp
G28 W ; home all without mesh bed level
G0 Z60 ; get head above bed to keep it cool
M140 S[bed0_temperature] ; set bed temp
M104 S170
M190 S[bed0_temperature] ; wait for bed temp
M104 S170
G28 W ; home all without mesh bed leveing
G80 A-35 B-30 C10 D30 E60 F20 H0 I-70; mesh bed leveling
M104 S[extruder0_temperature] ; set extruder temp
M109 S[extruder0_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0 ; reset extrusion distance
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
Feel free to message/post for more details.
Re: Different live Z adjustments for different materials.
I'm using slic3r, so I suppose I can modify just about anything.
But I think there is something else wrong. I just finished another ABS print and tried to check pinda-hotend distance. It's definitely less than thickness of credit card (I did check with credit card specifically, my calipers says it's 0.7 mm thick).
However:
Afer last print "Live Z adjust" to let my hotend touch paper on heatbead has fallen down to -2.705mm. Now this is just plain wrong, something is wrong with Z axis. Suggestions?
Re: Different live Z adjustments for different materials.
Something is definitely wrong, and It's start's to look to me like a firmware issue.
I moved Z axis via setting->move axis->z menu. It went up as expected, went down do 0 and there was HUGE gap between hotend and heatbed.
I adjusted it with live z adjust: -2.442mm was requred to catch sheet of paper.
Moved z-axis up by 1mm via setting->move axis->z. It refused to go down at this point. I moved it up another 1mm, and then it allowed me to go down one mm.
Re-adjusted LiveZ to catch paper again: -3.622mm
Moved Z home with Calibraton->Auto Home. Now I need LiveZ of -4.610mm to catch paper. I don't think that's what's supposed to happen. Firmware 3.0.11. Please advise.
Re: Different live Z adjustments for different materials.
If your probe is less the a credit card, go up to match this thickness. Probes too low have opposite effect and will not read properly.
The metal calibration points in bed create a certain beveled signal range for the probe to detect. Too low or too high can provide a wide range of sensitivity.
You should raise PINDA and try to recalibrate.
Re: Different live Z adjustments for different materials.
I have raised my PINDA probe to 1.2mm above hotend and now liveZ is in more sane value of -0.945mm but there is some other underlying problem that I am experiencing. Each consecutive print requires me to lower liveZ by another ~0.03-0.05mm to get good first layer. It seems just like my live adjustment os offsetted by something after each print; It's a smaller amount than I was experiencing before, but still this worries me.
Actually, it looks like liveZ i am setting during print are totally discarded for next one.
Re: Different live Z adjustments for different materials.
I have switched to PLA for few prints, and they come out consistent - afer initial calibration I don't have to adjust liveZ between prints.
Switched again to ABS and problems again - hotend tip was way above bed (~0.2mm). I am using temperature calibration right now, I assumed it should offset any temperature-based changes in PINDA response. Having to adjust liveZ at every print becomes a major PITA right now :/
Re: Different live Z adjustments for different materials.
Like I said, you should turn off temp calibration and just change start code to have the PINDA away from the bed during heatup. Much easier and more consistant.
Re: Different live Z adjustments for different materials.
Like I said, you should turn off temp calibration and just change start code to have the PINDA away from the bed during heatup. Much easier and more consistant.
Looking trough your g-code:
M140 S[bed0_temperature] ; set bed temp
M104 S170
M190 S[bed0_temperature] ; wait for bed temp
M104 S170
What's the reasoning behind that? If I read correctly, you are setting extruder temperature to 170'C regardless of material while bed is heating up.
Re: Different live Z adjustments for different materials.
Ultimately I went with start g-code of:
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 leveing
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 pritn area
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
Doing some test prints now. First two went well 🙂
Re: Different live Z adjustments for different materials.
What's the reasoning behind that? If I read correctly, you are setting extruder temperature to 170'C regardless of material while bed is heating up.
That's fine. Heat the nozzle to a temperature where oozing won't occur and then do the 9-point calibration and then heat the nozzle to extruding temp.
Heat both nozzle and bed at the same time to save a few minutes.
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: Different live Z adjustments for different materials.
Why not do the levelling before heating up things?
Re: Different live Z adjustments for different materials.
Why not do the levelling before heating up things?
I considered it for a while, and there can be multiple factors, but I was mostly concerned by thermal expansion of heatbed. It (propably) has linear thermal expansion coefficient of 36e-6/K, so there can be a difference of ~0,01728mm between room temperature and 100'C, and that's significant for z-level.
Re: Different live Z adjustments for different materials.
Why not do the levelling before heating up things?
The bed needs to be at printing temp for the 9=point calibration. The nozzle needs to be hot in case there was some ooze after last print not not hot enough to generate ooze during the calibration.
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…