Need some help. Print is baked into print bed

As you can see from the pics below I ran into a problem. It happened 3 times in a row but this last is the worst.
My large prints are getting baked into the print bed.
At first I thought it was a leveling issues so I bavked the leveling up further and further. Typically I level until the calibration paper is snug. The last one I leveled until the calibration paper just fit under the nozzle in and out with no snugness or pulling at all.
Any ideas what could be going wrong?
Thankfully I have a spare bed as this one is hosed mow. No amount of scraping is getting this to come off.

What filament are you printing with? I would use glue stick or one of the nano coatings to get it your prints to stick and be releasable. PETG often sticks too well to PEI. I use Prevailent T-80 on one side and Vision Miner Nano Polymer Adhesive on the other I find Nano does a better job with ASA and Prevailent T-80 releases the other filaments easier after the bed cools. For long or high value prints I will put a coating on before the print. If I am doing fast prints with cheap filament I will just run it until something doesn’t stick I can usually get 20 or 30 prints before needing to re-coat. I haven’t had any issues with prints coming loose or sticking too well printin PLA, PLA+, PETG, TPU or ASA. YMMV.

Glue stick works but needs frequent reapplication and gets gummy if you don’t wash the print plate.

I’m using Black Snapmaker PLA.
Also, it’s not just a release issue. If you look close ot looks like the PLA is actually baked or burned into the print bed.

PEI has a glass transition temp of about 217 C and a melting temp of 370-400 C, unless things are getting much hotter than they should it is a mechanical bond. I suggest you remove the PLA by sanding if it won’t come off with acetone or ethyl acetate and a scraper (ensure adequate ventilation for both chemicals). The idea is to get the plate smooth so you can use the other side for testing. Level the bed, put some Elmers School glue stick on the bed and print the first layer test ( at 210/70 C and see what happens.

I ruined the centre of my bed when printing PETG direct. It’s especially worse when a print fails and you have no bonded bulk to get a grip on and so have to resort to scraping. In my case a razor-sharp blade preferred to bury itself in the PEI sheet (Snapmaker’s own) rather than separate the PETG from the bed, leaving me with a hole in the bed down to the next layer. Now I always use something else between the bed and the print!

What temperature are you running the heated bed at for these print and filament?

205 and 70

That’s why; 70 is too hot for PLA; usually 60 at most. Bed temp should be generally 5-10 degrees lower than the filament’s glass transition temp, which is around 60 for PLA.

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Interesting. I’m using the default luben settings for their PLA.
Do I even need to heat the bed?

I would, yes, otherwise the first layer will not bond to it enough and the print could become easily detached while printing.

I use 60 for PLA, 80 for PETG, and 95-100 for ABS. I also use a spritz of hairspray with PETG to assist with both first layer adhesion as well as releasing when complete.

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Dont make the mistake to use acetone!!!
I had an ASA print sticking too well and searched the internet. There I read that you could use acetone to dissolve and release/clean off ASA.
This bs killed the upper third part of my print sheet. It didnt only attack the ASA, it made my PEI (original Snapmaker that came with my printer) soft and it got scraped off while I was trying to remove the ASA.

Thanks for the help!
I did 2 things on my spare bed.

  1. Releveled again to make it snug, then raised it slowly until I could slide the calibration paper under it in and out.
  2. Dropped the heated bed down to 58. I figured better to go a little low and have it come loose then another burn in.
    This worked perfectly and I think your bed temp had more to do with it then my releveling.
    I printed 2 large pieces with fast settings and they popped off perfectly. Just had to scrape the skirt a bit.
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I don’t have any so haven’t tried uet.
I ended up trying to soften it with a lighter and it helped. I think i might try putting it back in and cranking the bed heat to maximum.
Otherwise this might be a lost cause and i might try aceatone before tossing it.

It will come off, Heat the bed up first and then use a stanly knife blade.

Yep. Forgot to update. I cranked it up to max heat and let it just sit for a bit.
I then scraped it with the normal spatula and it came off.
I also had an old print hed that had the same issue and did the same. That required a lot more work but it all came off eventually.