PEI Sheet damaged by auto-leveling checks after first use  

RE: PEI Sheet damaged by auto-leveling checks after first use

I havent experienced this with my MK4s - I've only completed 2 prints though, and my sheet is like new. 

I do use a scraper after each print though, to rid the bed of little bits on plastic left from the probing.

RE: PEI Sheet damaged by auto-leveling checks after first use

Hi Matthew,

I am seeing the same issue on my brand new MK4S that I ordered fully assembled (not kit). I've made about 10 prints so far and started noticing the same problem you are seeing yesterday (my MK4S arrived on Thursday). I am disappointed that the machine has messed up my once beautiful PEI sheet with dots and raised bumps - see picture. Matthew, were you able to find a solution?

RE: PEI Sheet damaged by auto-leveling checks after first use

Is it actually the nozzle that scratched? Or is it the filament that melted?

When printing pla, the default bed leveling setting is 170 degrees for the nozzle temperature.

That's why the product flows out slightly and can get on the bed.

In my case, after modifying the g-code to set the bed leveling at 150 degrees for the nozzle temperature, the marks like the one in the photo disappeared.

RE: PEI Sheet damaged by auto-leveling checks after first use

Same thing happened here with my Mk4 when I got it last year. caused bumps and scratches to my smooth sheet, no problem whatsoever with the satin and textured sheets. 

One thing I noticed is that when doing the "loadcell calibration", it says to "tap" the nozzle, but I always had to "press" on the nozzle with a bit of force for it to detect anything. I had seen other people say the same thing, so I went with that. But I always wondered if the loadcell wasnt sensitive enough and caused the nozzle to push too hard on the bed.

Now I can't make any conclusions for the moment, but I JUST tonight upgraded my MK4 to MK4S with the upgrade kit, and for some reason, now I really only have to barely tap the nozzle during calibration for it to work...

I still have a second PEI sheet in pretty good condition from my MK3S so I'm gonna be using it with the MK4S for a while to see if its gonna damage it as it damaged the other one.

Posted by: @matthew-10

Hi all!

I know from searching the forums/reddit that this has been a problem for Mk4 users, but it seems that it was fixed by a firmware update at some point. I would have assumed that this also applied to the Mk4s. This is my first experience with a prusa printer, and I've only printed two small PETG prints on the PEI sheet, and there are permanent raised bumps in a grid arrangement from the auto-leveling checks that are done before a print begins. This is... annoying. I'm lucky to have a texture sheet as well, that I have been using without issue, but I do want to be able to use the PEI sheet too. Have others experienced this? And what are your solutions, if any?

RE: PEI Sheet damaged by auto-leveling checks after first use

When I got my new MK4 in August 2023, I first printed a few files from the included stick.After that, I also had a "damaged" spot.
Then wrote to support and checked that the thumbscrews for the nozzle were tight. And also sent them more detailed photos of the PEI sheet.
The spots didn't go away with isopropanol either.I then got a new PEI plate from Prusa under warranty.
After a few months, I cleaned the "damaged smooth PEI plate with acetone. After that, the weird spots were gone. 🙂
But as far as I know, you should only use acetone on the smooth PEI plates. Not on textured and not on satin. And not that often anyway.

RE: PEI Sheet damaged by auto-leveling checks after first use

I have not had this happen.  Occasionally if I didn't clean the nozzle I've had it leave plastic on the probing points, bit that's it.

RE: PEI Sheet damaged by auto-leveling checks after first use

The auto-leveling mechanism on my MK4 decided that part of the bed was several millimeters below the rest and proceeded to make a large gash in the PEI sheet.  So, yes, it still happens.