Failing first layer  

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tommy.s6
(@tommy-s6)
Active Member

Just a few days ago, everything was working perfectly. Started having trouble with layers 1 2 and 3. Before attempting to fix it, my first layer started lifting up the plate and stick to the nozzle. I've got MMU2 so i figured one of the filaments was dirty and got something stuck in the nozzle. So I cut all filaments, cleaned everything up, changed the nozzle and now my first layer always looks like this. Every time the printing changes direction it seems to lift up from the plate slightly or completely stick to the nozzle. Also this causes a curl on the little rectangle at the end. I always cleaned my plate with rubbing alcohol in between prints and never had to use adhesive. I always printed PLA at 215C nozzle and 60C heatbed. I've recalibrated XYZ multiple time, Z multiple times and tried different live Z adjust values. Whatever i set the live adjust to, it always curls, always lifts up the plate. How can i stop filament from sticking to my nozzle?


Posted : 13/03/2019 5:02 pm
Tim
 Tim
(@tim-2)
Illustrious Member

Hot Water wash: as needed
Handle the bed only by the edges.
Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.). Rinse well in hot water - if you have very soft water, rince a bit longer.
Dry the bed with a fresh paper towel.
Handle the bed only by the edges.
Place bed on printer.

Alcohol rinse: every few prints
Once in a while, an alcohol rinse is helpful.
Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

Streak test: when contamination is suspected and after a wash
With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates. If you see any streaks, the bed is dirty and needs a wash.

Acetone wash: infrequent
Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

It is always wise to get more than one opinion...
Posted : 13/03/2019 9:07 pm
tommy.s6
(@tommy-s6)
Active Member

Thanks for the suggestions, i'll try them out

Posted : 16/03/2019 8:44 pm
Bob
 Bob
(@bob-2)
Trusted Member

Looking at your calibration print I see tearing at several locations, I'm wondering if maybe your live Z is too close to the bed. One thing that helped me with live Z is a Jeweler's loop, they're very inexpensive and can give you a good look at your first layer profile. After I do a calibration print I remove the print and using a sharp knife I cut a section of the filament and look at it under the loop and compare what I see to what Prusa publishes as proper first layer squish. I have great first layer squish now.

-Bob

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Posted : 26/03/2019 9:24 pm
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