Trouble with prints curling and popping off after a few layers
Hello,
I've got a Prusa MK3S with the nice smooth build plate and I'm having two problems, one I think I've fixed and one I'm really stuck on.
First problem was repeated jamming after the first 5mm or so of printing height. I asked around, with my Makerspace and other 3D printing friends and followed a friend's advice. I followed Prusa's instructions on how to take the print head apart and added a wrapping of white teflon tape on the threads of the metal tube that connects the heat block to the heat sink. The intent is to reduce heat flow into the heat sink a little so the nozzle stays at temperature but areas above won't so much to cut down on heat creep and jams. This seems to have worked.
BUT, now I have a new problem: Prints just won't stick to the plate after the 3rd or 4th layer. They curl up at the edges and up they come. I have adjusted the Z-height correctly and Z-height adjust layer sticks fine. So, I followed Prusa's online instructions on how to improve plate adhesion. I washed with Dawn dish soap and water, rinsing and drying quickly. I never touched the plate with fingers, I held it by edges only. I wiped with 91% isopropal alcohol, with clean paper towels, several times. I wiped with acetone, several times. I "re-surfaced" using a roll of 600 grit sand paper, very gently sanding the surface with circular motion as instructed, then I wiped with isopropal alcohol again. Then I tried wiping with acetone, again. After each of these attempts the same thing would happen. I'm using a very simple test print with PLA, nozzle at 215C and the plate at 60C. I've printed this shape many times before I added the teflon in the head and it worked fine.
This all started because of all the jams I kept getting. I did in fact use good, Prusa PLA, dried in a dehydrator for hours and hours. I have the up to date firmware, I'm using Prusa's slicer with default MK3S settings. I finally broke down and emailed Prusa for help, no answer yet.
Can someone please help me? I really enjoy using this thing when it works. It worked great when it was new, but then it stopped and its been nothing but headaches since.
Thanks,
-John C.
RE: Trouble with prints curling and popping off after a few layers
Hi John,
It's hard to diagnose without being there, so I'll just try to make a few suggestions.
Modifying the system(teflon tape) should be the fix of last resort. I would lookup "3d printer filament jams" first, on this site or google, etc.
You said you disassembled the hot end to apply the tape. I'd double check my work. like is the thermister properly mounted, are the fans working properly, screws not too tight or loose, etc.
If that's all good. Next I'd try playing around with temperatures, lower the nozzle temp a little, maybe like 5 degrees at a time, raise or lower the bed temp a little. Also look around your printing area, did something change that might cause a draft on the machine?
If all else fails, you could try removing the teflon tape and see if it goes back to the original problem and take a new approach from there.
on aside note: I've had my printer with the same smooth pei sheet for about 2 years now and my prints still stick down pretty well. I only use soap and hot water and sometimes alcohol for a quick wipe between successive prints. I don't recommend acetone or sanding, but that's just me.
There are certainly other possibilities, perhaps someone else will chime in with additional ideas. Good Luck.
RE: Trouble with prints curling and popping off after a few layers
@johndavidcook
There are hundreds of threads on here relating to first layer problems; 90% are resolved with scrupulous cleaning and most of the rest with calibration - you did clean with soap and plenty of HOT water..?
Many clogs are caused by leaving the print head at temperature, preheated, without printing immediately. The resulting cooked filament causes the problem.
Restore the printer to it's orginal condition and start over with the side of the build plate you have not worked on; properly cleaned, and come back if you still have problems.
@mlong is right to suggest tweaking the hot end temperatures if a particular filament has issues but default first layer settings usually include enough extra heat to make sure they stick - if everything else is OK.
Cheerio,
RE: Trouble with prints curling and popping off after a few layers
@diem
Thanks for the answers. Yes, I did clean the build plate very carefully, several times, with several solvents, including plain dish soap and hot water.
One thing a friend asked is if I somehow got heatsink grease inside the plastic pathway when I re-assembled things. Well, I suppose its possible. Then none of those solvents would remove it. So I looked around and toluene will remove heat sink grease, none of the other solvents I tried will. So next I will dismantle the head again, soak in toluene, clean carefully, wipe the build plate with toluene, with clean paper towel, moving from one side to the other each time so to wipe it away instead of just moving it around. Then I will re-assemble, without teflon tape, and try again. Yes, I have the genuine Prusa instructions and I follow them very carefully. Mechanically, the printer seems to work fine. I can even adjust the Z-height very carefully and have done so.
One site suggested that this is "thermal curling" caused by the plastic shrinking with temperature and curling up. Most of the suggested fixed are already built in to a Prusa Mk3S, like a heated build plate, keeping the plastic very dry, controlling the temperature well, etc.
Thanks for the pointer about leaving plastic in the printer, heated, and not printing right away. I'll avoid that.
Thanks again.
-John C.
RE: Trouble with prints curling and popping off after a few layers
I must thank all those who offered help and I must also apologize.
Turns out I was using low quality PLA and did not realize it. As soon as I changed to genuine Prusa PLA all the problems went away.
I did six test prints including the classic "Benchy" boat and all is well now. I still have the teflon tape wrapping inside the head and I'm going to leave it there since things are working so very well now.
Thanks again,
-John C.
RE: Trouble with prints curling and popping off after a few layers
@johndavidcook
Hi John,
May I suggest that you do remove the PTFE tape from between the heatbreak and the heatsink. t... heat is supposed to pass from the heatbreak into the cooling fins. PTFE is an insulator. It will reduce the efficiency of the cooling fins,
Heatsink paste is better.
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK