Live Z Adjust Constantly Decreasing  

Re: Live Z Adjust Constantly Decreasing

+1

I've the same problem, it started with -0.500 an now it's at -0.900, I print only ABS.

Re: Live Z Adjust Constantly Decreasing

+1
The printer worked (not at all to my satisfaction, though) for PLA and PETG. Since I switched to ABS, I have exactly the same problem. Basically, it never sticks, since the height is way too high after starting with the print, even though I did the live Z adjustment very precisely.

Assume it is connected to the higher temperature for ABS.

I consider this a serious flaw, and apparently Prusa does not care, given the time these complaints are out.

I just hope people interested in buying a 3d printer read this before taking a decision.

Re: Live Z Adjust Constantly Decreasing

I've noticed this same problem with my printer now (got it last week, and it's running the latest firmware).

First thought it was because I started printing more with PETG after first dialing it in with PLA.
But I basically have to live adjust Z for every new print.

Re: Live Z Adjust Constantly Decreasing

did you enable the temperature calibration, or is it disabled (my recommendation) ?

Re: Live Z Adjust Constantly Decreasing

I run my MK2S in my garage where the temperature varies by 30 degrees day to day. I was constantly chasing a good live-Z #.

I used this gadget to adjust my pinda height (mostly just so I have a consistent height when I change nozzles, but I also got my 'best' live-Z using it (-.165)

I ran the temp calibration and turned temp calibration: ON.

I put my z-axis at 100mm+ while the printer warms up, then it does it's 2 minute pinda warm up before each print and I was able to stop messing with my live-Z.

admittedly, it's also summer now, so my garage is always warmer (70f+), the gadget itself may have put my pinda at a more accurate height. The temp calibration may not be needed, but I do believe the raised z-axis while warming is. I was mostly tired of bad first layers and did a little bit of everything at once, and it worked. 😀

Re: Live Z Adjust Constantly Decreasing

I run my MK2S in my garage where the temperature varies by 30 degrees day to day. I was constantly chasing a good live-Z #.

I used this gadget to adjust my pinda height (mostly just so I have a consistent height when I change nozzles, but I also got my 'best' live-Z using it (-.165)

I ran the temp calibration and turned temp calibration: ON.

I put my z-axis at 100mm+ while the printer warms up, then it does it's 2 minute pinda warm up before each print and I was able to stop messing with my live-Z.

admittedly, it's also summer now, so my garage is always warmer (70f+), the gadget itself may have put my pinda at a more accurate height. The temp calibration may not be needed, but I do believe the raised z-axis while warming is. I was mostly tired of bad first layers and did a little bit of everything at once, and it worked. 😀

What gadget are you using? I see no image or link to gadget?

Re: Live Z Adjust Constantly Decreasing

What gadget are you using? I see no image or link to gadget?

Sorry about that https://www.thingiverse.com/thing:1977997

Re: Live Z Adjust Constantly Decreasing

Why couldn't we just auto level BEFORE heating the bed? OR even better, have a preset bed temp before auto levelling, then after set the real bed temp. This will account for ambient temperature.

Re: Live Z Adjust Constantly Decreasing

Why couldn't we just auto level BEFORE heating the bed? OR even better, have a preset bed temp before auto levelling, then after set the real bed temp. This will account for ambient temperature.

http://shop.prusa3d.com/forum/improvements-f14/begin-print-cycle-time-reduction-calibrate-while-h-t5673.html

Re: Live Z Adjust Constantly Decreasing

HI

i have my prusa now for 2 weeks and i can't get a good print to start.
when i start up the printer i need te change the live z all the time .

when i start i need to change it to 250 .
if the printer does a second print it needs to be changed to 170 to get a good layer .

it's really frustrating,

is there a fix to it ?

Re: Live Z Adjust Constantly Decreasing

HI

i have my prusa now for 2 weeks and i can't get a good print to start.
when i start up the printer i need te change the live z all the time .

when i start i need to change it to 250 .
if the printer does a second print it needs to be changed to 170 to get a good layer .

it's really frustrating,

is there a fix to it ?

This seems to be a problem that is dependent on your PINDA probe. The fixes that people like are to make sure they warm up the printer with Z at 100mm to keep the PINDA probe temp stable. (Warming up while Z is down seems to exacerbate the problem.) To handle this, people have modified their Start GCODE in the slicer to something like this:

M115 U3.0.12 ; tell printer latest fw version
M83 ; extruder relative mode
M104 S170; Extruder to 170
M140 S[first_layer_bed_temperature] ; set bed temp
G28 W ; home all without mesh bed level
G1 X0 Y0 Z125; home X axis Lift to 125
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S170 ; wait for extruder temp to hit 170
M104 S[first_layer_temperature] ; set extruder temp
G80 ; mesh bed leveling while rising in temp
G1 Y-3.0 F1000.0 ; go outside printing area
M109 S[first_layer_temperature] ; wait for extruder temp if needed
G92 E0 ; reset extrusion distance
G1 X100.0 E9.0 F1000.0 ; intro line
G1 X200.0 E12.5 F1000.0 ; intro line

Which also does the calibration at a lower extruder temperature to help fight oozing.

Re: Live Z Adjust Constantly Decreasing

Wow, why isn't this included in the Prusa printing handbook? The official Pruca Slic3r settings should also have the Z lift commands in the G-code.

Everything has worked flawlessly until I started a tricky PETG project. Had to abort the first print after a few layers, and the piece i scraped off had a super nice and smooth underside. I immediately started the next print, but now the first layer failed miserably. I started to do lots of test prints, and got random results. I couldn't figure out what the problem was, I started to suspect some nuts in the printer frame had come loose, but couldn't find any problems. I pulled my hair an printed failed test models all night until I finally found this thread at 02:30 in the morning.

Now I let the printer cool down completely before each print, and then do the warmup with Z high up. The first layer is beautiful again! I've added the Z-lift G-code to Slic3r, will see how that works out.

This problem is also mentioned on Prusas github, scroll down to "Temperature Calibration": https://github.com/prusa3d/Prusa-Firmware/releases/tag/v3.0.11-RC1

Re: Live Z Adjust Constantly Decreasing

I was having the same issue today where I would constantly have to adjust the z level adjust -600 (-600, -1200, -1800, etc) every print and found this topic on reddit. https://www.reddit.com/r/3Dprinting/comments/5a62o1/prusa_i3_mk2_need_to_live_z_adjust_05_mm_every/

Once I modified the z level adjust while printing the V2Calibration from prusa, the z level adjust stuck.