New glass bed adhesion issue
I bought an Ender 3 Pro about three years ago and picked up a glass bed at the same time (the original one with the Creality logo across the center). Well after all this time the coating has worn out so I bought a new bed. This is the new one with a much smaller Creality logo at the bottom.
This new bed had a plastic film that needed to be removed, but it left a lot of sticky gunk on the glass. After working with it using alcohol, dish soap, and more alcohol, I finally got everything nice and clean. However there is still a very noticeable difference in the coating between the old and new bed that you can see and feel.
With the new bed in place I performed the regular leveling process. This basically starts with the paper test to get it close, followed by 5-point print tests to dial it in. And because of the age of my printer it came with a warped aluminum bed, so I use layers of foil under the center of the glass to make sure the entire bed is completely flat. This is such an easy process that I literally only check my leveling once a year because in the past all of my prints have stuck to the bed without any problems.
To give you an idea of how confident I am in this process, my test for new filaments is a calicat printed at 50% (10mm). If you are familiar with the model, you know the cat has feet, so at this print size there is extremely minimal contact surface with the bed, and I use that to help dial in my nozzle temps for each new filament. Bed temperatures have always worked well at 60-65C, and nozzle temps can range between 195-215.
I can barely get anything to stick to the new bed, even larger prints. I have typically had the best luck with the first layer being about 0.15mm, but in testing the new bed I have ranged from 0.28mm down to so thin it looks like the filament was wiped on, tried using a higher flow rate for the first layer (causing a massive elephant-foot), tried adjust the z-offset in Marlin... Even my 5-point print test can be slid off the bed before the bed starts to cool so I almost never even need to use the scraper.
I'm starting to feel like I got a bad coating on this bed. With the original glass it always just worked, so I'm frustrated that the "new improved" glass is turning out to be such a disaster. I've been battling this problem for four days now and cannot complete any prints taller than a few mm before they break loose. One suggestion I ran across was to lightly rough up the surface with some 1000-grit sandpaper. Seems like it might give some bite to the coating but at this point I don't know what else to try. Any suggestions?
An update to this issue... As a sanity check I swapped my old glass bed back in again last night. There are heavily used areas where just about nothing sticks any more, but printing my test pieces in the lesser-used regions quickly produced excellent results (after re-leveling the bed for the new glass, of course). Even before I had the leveling perfect the test prints were requiring the use of the scraper to get them off the bed again.
For testing I started with my usual 5-point bed leveling test print. Once that was close I switched to a solid 20mm cube which I print with zero infill and no top layers. Even for this small an item I have to let the bed cool for a couple minutes or it requires a lot of force with the scraper to get the part loose from the bed. THIS is what I was expecting from the new bed as well, but I have to say whatever was changed in the coating is a huge disappointment.
Unfortunately this was actually bought for me as a holiday gift LAST year, so it's far too late to return it to Creality, but as far as I can tell the new bed is not useful for anything. Guess it's time to start experimenting with other bed materials unless someone has any other ideas for me to try. I don't use tape, glue sticks or hair spray -- there should be no need on the Creality glass to use anything other than 91% IPA to occasionally clean it.
@shdwdrgn I had the same issues with the new glass, despite IPA cleaning etc, so started using 3DLAC. I had to give the glass a good scrub after using it, so I cleaned the glass with washing up liquid, a nailbrush and very hot water. After rinsing, I let it air dry in a rack. After that it stuck perfectly without glues, so much so that large prints had to be frozen before they would release.
I did find that my 99% IPA seemed to leave a residue behind, so that didn't help.