Notifications
Clear all

Selftest passed, Z-Height is off  

  RSS
b4de4nd
(@b4de4nd)
Active Member
Selftest passed, Z-Height is off

Hi

So i just got around to assembling my new MK4. I already have one MK4 but that was one of the 100 on realease and is therefore factory assembled. Now i have a baseline to compare to.

After my build the printer failed y-axis 1 time, but ran through it all afterwards. My factory assembled machine did the same actually.

Ive test printed the scraper on the usb, and im not keen on the first layer, if seems to high. Ive looked through articles, and im not sure what to do here?

The rest of the print looks fine.

Posted : 05/12/2023 6:14 pm
ChiefSmeg
(@chiefsmeg)
Trusted Member
RE: Selftest passed, Z-Height is off

I know that there is a way to live adjust the Z height and that first layer does look a little off. Maybe try another quick print - you could always stop it after the first couple of layers and have a look. 

Posted : 05/12/2023 6:42 pm
b4de4nd
(@b4de4nd)
Active Member
Topic starter answered:
RE: Selftest passed, Z-Height is off

Its correct you can live adjust the Z, but only for the current print. Its the Z-height measurement in bed probing theres and issue.

If you wanna adjust your z height for current layer, you can press the knob while printing to get the menu to do so.

I tried several prints, and prints i sliced myself instead of using the premade gcodes on the usb that came with the machine.

The factory assembled machine does make a neat first layer, the kit machine does not.

Posted : 06/12/2023 8:24 am
ChiefSmeg
(@chiefsmeg)
Trusted Member
RE: Selftest passed, Z-Height is off

Didn’t know it was for the current print only!

your nozzle tip is clean when you probe yes?

Posted : 06/12/2023 9:45 am
b4de4nd
(@b4de4nd)
Active Member
Topic starter answered:
RE: Selftest passed, Z-Height is off

Yes nozzle tip is all clean, nozzle cleaning is also passing without errors, on which ive had issues with my factory assembled machine before. it was the initial temp raised to 195 for cleaning, after i kept it at 170 is not a problem anymore. I dont leave residue on the nozzle head after a print, if theres anything i clean it before print.

Posted : 06/12/2023 11:51 am
Username7688
(@username7688)
Member
RE:

I have the same issue with my MK4 kit (delivered OCT'23). Initially bottom layer looked perfectly fine, but at some point it changed and first layer always is some value too high. No matter if I use the original .4 nozzle or the v6 adapter with a .6 nozzle, PETG or PLA, Satin or Smooth PEI. When I manually set a z-offset of ~ -0.05 in Prusaslicer the first layer looks fine in some areas, but not all. So somehow the measurements taken by the bed leveling are off, ie the nozzle doesn't have a consistently false z-height offset to the printbed.

I have performed this test several times https://www.printables.com/model/562085-prusa-mk4-bed-level-check with somewhat consistent values. When the shims arrive I will install them and re-do calibration and the tests and compare values for each measurement point. If the shims also do not change anything about the z offset from the automated bed leveling then something with the loadcell must be faulty (though I do not know how that can depend on the xy position).

 

This post was modified 3 months ago by Username7688
Posted : 13/12/2023 7:44 pm
b4de4nd
(@b4de4nd)
Active Member
Topic starter answered:
RE: Selftest passed, Z-Height is off

I ended up redoing my nextruder assembly, and this time i loosened screws to an uncomfortable amount, and now its reading the right Z- value. However I now struggle with X-axis rattle noise :/ its not easy 😀 

Posted : 17/12/2023 4:57 pm
Username7688
(@username7688)
Member
RE: Selftest passed, Z-Height is off

Which screws did you leave loose? I talked a bunch to support and one of the recommendations was to slightly loosen the screws behind the fan attaching heatsink and loadcell to the Nextruder. It did slightly help.

Posted : 17/12/2023 9:08 pm
Username7688
(@username7688)
Member
RE: Selftest passed, Z-Height is off

Update from my side: What ended up helping me with my first layer quality was making sure nothing in the Nextruder was too tight (obviously still tight, but not need-extra-force-to-loosen-tight), and also pre-heating the heatbed for 5 minutes before each print and a clean nozzle. Since then I get a consistent first layer.

Posted : 24/12/2023 8:53 am
b4de4nd
(@b4de4nd)
Active Member
Topic starter answered:
RE: Selftest passed, Z-Height is off

it was the screws for the nextruder "cover"/housing, the screws that connects the nextruder to the x-axis and the fan screws

 

Posted : 04/01/2024 10:54 am
Share: