I’m having an issue with inconsistencies in the heated bed when I’m 3d printing, at first it was one hot spot close to the center of the bed where the filament would stick extra hard which hasn’t been much of an issue but I just tried printing a group of things that spans the width of the bed minus about 50mm on each side and one side of the bed isn’t getting as hot as the rest of the bed so the filament doesn’t stick which messes up the whole thing. Anyone have some wisdom they’d like to share?
I’ve heard that the larger machine’s printing beds are pretty uneven. How are you measuring the temperature differences? I’m more inclined to think it’s a level issue than a temperature issue. Which machine do you have, and which calibration are you using? Several people recommend doing an 11x11 calibration instead of the default 3x3.
I’m not measuring the temps with any device, just noticing the differences in the brim or skirt and the differences in adhesion. I have the A350 and I’ve run the bigger of the calibrations several times, it’ll do okay for a run or two then go back to having either hard stuck spots in the center or it won’t adhere at all on one of the sides. I’m guessing that I’m going to have to calibrate before every run, not a terrible hinderance or loss of time, just slightly annoying.
It’s easy to check how flat your bed is with a straight edge and a flashlight. Put the straightedge on the bed, and shine a flashlight from behind. Any light you see seeping under the straightedge is unevenness.
People on the forums have spent some time manually correcting really bad beds. Two results I found searching the forums for “flatten”:
I’ve also heard that some people will preheat the bed, then quickly do a 5x5 calibration before the bed cools off too much. Although there was talk of the firmware preheating the bed before calibration rather than doing it cold. I haven’t kept up with that (I have an Original, so I only know about the 2.0 problems from reading the forum.)
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There’s an option in the menu on the touch screen to calibrate with a hot bed. So that’s just a matter of enabling it.
I often do full-bed prints in PLA on my A350T without real issues.
What I do before every large print:
- Take off the print sheet, clean it with wet kitchen paper and dish soap (I use green Dreft), rinse it with water and dry with kitchen paper. I never used isopropyl alcohol or acetone etc.
- Replace the print sheet,
- Make sure there is no filament residue sticking out at the nozzle (since you use the tip of the nozzle as the reference for calibration, any hardened filament will result in a nozzle that is calibrated too high),
- Do a heated 5x5 calibration,
- I use the calibration card that came with the Snapmaker. I lower the head until I can barely still slide the card back and forth, but without it curling up. In my experience, if I lower until I can pull but no longer push the card, than the print head is often somewhat too low for the first layer. Although this differs from the Snapmaker manual,
- Then I start the print with two brim lines and keep an eye on them. If all is perfect, then the lines have a flat top, the correct and consistent width and touch each other along the full length.
Generally if I have issues, then it is due to me having not followed above procedure, or rushed through it.
Regards,
Johan
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I didn’t have good luck with paper products. I always ended up with some lint left behind. I’ve had better luck keeping the build plate covered. When I do clean it, I use a cotton rag to wipe it.
That’s the amount of tension on the card I ended up using as well. If I can’t push the card, I end up squishing the first later, which causes some texture issues. I’ve even had prints fail because the extruder forces previously deposited filament up off the bed, which later snags on the print head and pulls off.
I also like to print a 0.04mm square after calibration. I have an original, so my bed is only 125mm square. If I had a 350, I’d make some kind of fractal square instead of a solid square. The original was much less prone to level issues, so my goal is to check the thickness of that print at the 4 corners and the center. I usually spot issues while it’s laying down the outer and inner walls, and stop the print before it even starts the surface. Repeat until I’m happy with how that thin square looks. I ended up with vastly different pressures on the card at the four corners, but my prints were very nice.
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Another suggestion: always wait long enough to allow the bed and nozzle to fully come up to temperature:
- When doing the heated bed calibration: let the bed come up to temperature, wait for another 5 to 10 minutes and only then start the 5x5 calibration,
- Before starting a print: first go to the control menu and manually set the bed and nozzle temperatures. Give it enough time to get to a stable temperature.
Also make sure your e-step value is calibrated!
Below pictures give an indication of the result (line width 0,4mm; first layer 0,2mm thick):
Bottom left corner of the build plate:
Top right corner:
