Not enough first layer squish?
Having had a MK3 and currently a Mini and now a MK4, I'm used to dialing in the first layer myself. Admittedly, I always leaned toward too much squish vs not enough.
I'm using the "0.15 quality" profile and Prusament Galaxy Black to print the Mini "nut" that I use as a sample print for my filament collection. Each attempt on my MK4 (kit build) has failed with the exact same two problems.
First, the first layer seems to go down fine but the innermost line of the inside perimeter fails to adhere to anything and for a small portion around the circle just drags through midair until it finds something to adhere to. This happens for the first 3 or 4 layers then seems to stop happening. This has never happened on my Mini after printing 40+ of this same model.
Second, somewhere after the first 5ish layers, the print detaches from the bed. Not entirely detached because I stop the print, but it is only held down by maybe 20% of the first layer when I stop it around layer 10.
To me, it seems like there isn't enough squish on the first layer or maybe I need to adjust the extrusion multiplier to push out a little extra filament. But, this is a brand new spool of Prusament on a MK4 and shouldn't need any fiddling with settings.
I washed the textured sheet with dish soap then wiped it down with alcohol and still it detached from the bed. I'll just go back to always using a glue stick (since that never hurt anything) but am curious about what I'm missing here.
RE:
After all the prints have been perfect for the first layer, I also have a little problem that I cannot completely explain.
So far it has only been with a new PLA Filament that I had not used before.On the smooth sheet of perfect first layer but not enough squish on the satin.
The filament doesn't even stick together and loosens from the print bed. I have already printed PETG, ASA and TPU, no problems. Perfect first layer.
The PLA prints perfectly except for the first layer.
MK4 alpha3 firmware.
RE: Not enough first layer squish?
I also get quite inconsistent layer squish in between prints when using the satin sheet with petg or pla back to back on the same gcode. However I would try the smooth sheet included, the textured is not really designed for PLA, if needed you can tweak live z on a per print basis with mk4, I dont remember how it is a hidden menu. You can also set a small offset in prusa slicer.
RE:
I have these issues as well using PLA on the PEI smooth sheet. I only print PLA on the PEI smooth sheet.
I regularly clean the sheet (wash and IPA wipe) to the point of being clean enough enough for surgery, but the lack of squish and jobs coming off happen every few prints. When a job works, the first layer is perfect. when it doesn't, I can clearly see ridges on the first layer.
I've gotten two "nozzle cleaning failure" errors over the last month, so that got me thinking the issue is if the nozzle doesn't get properly cleaned during the start up process, the load cell reading is off and the z leveling is too high thus resulting in not enough squish.
I think it would be better for Prusa to implement a "measure z-level offset" menu routine that the user can run after a nozzle/sheet change. This routine replaces the manual operation of the MK3S z-level set up with an automated load cell based routine. After it's complete, and the user is happy with the squish, the z level offset is stored in the printer and fixed (i.e. not calculated per print) until the user decides to change nozzle/sheet and rerun the routine.
At least for my MK4, the auto nozzle cleaning and z-level offset calculation on a per print basis is MUCH less reliable than the setup I have on my MK3S. The nozzle simply doesn't reliably get cleaned enough for z-level/bed leveling.
RE: Not enough first layer squish?
I cleaned the Satin Sheet with a sponge and soap. Then with IPA.I don't know if it was a coincidence but now also a perfect first layer. With long pressing of the "Tune" menu, the Z height can also adapt. But it was no longer necessary.
Overall, I am very satisfied with the first layer of my MK4. I also didn't have an error message from a dirty nozzle.My problem only occurred with this PLA. I'll keep watching it.
RE: Not enough first layer squish?
Thanks everyone. I think I’ll try the satin sheet to see if it’s any better out of the box then the smooth sheet. After that I’ll try tweaking the Z manually to see if I get better results. I’ll also see if I can get consistent (not necessarily accurate) first layers according to my calipers.
The textured sheets are not really suitable for PLA so use satin or smooth in that case.
Some new textured and satin sheets do seem to benefit from a drastic clean: Rub neat dishwashing detergent (Dawn/Fairy) into the surface and leave for a few minutes, rinse clean with very HOT water and pat dry with a fresh paper towel, handle by the edges only.
Cheerio,
RE: Not enough first layer squish?
I have also noticed this problem occasionally using PETG on the satin sheet. My theory is the same as mentioned where if the nozzle is not entirely clean the readings are off when the calibration is done. I'm not sure how to resolve this though, as there tends to still be a bit of ooze coming out of the nozzle even immediately after I wipe it prior to the cleaning step.