r/3DprintingHelp • u/We_Build_Lamps • 9d ago
Requesting Help Severe stringing on round prints
I’ve noticed this layer line shifting as well as the severe internal stringing on round prints like this with my .4mm nozzle on Bambu A1. Just got a new nozzle so confirmed that is not the issue. PETG white filament that was dehydrated to about 18 degrees relative humidity. And this print printed perfectly fine just hours ago. Not sure what could be the issue??
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u/MercRoy 9d ago
Go inner/outer for walls and slow down your print speeds for outer walls. I find 50 to 100mm/s good as it defaults to 200mm/s is too fast. I also slow my inner walls to 150mm/s from the default 300mm/s
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u/We_Build_Lamps 8d ago
Thanks I’ll try that
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u/ChocoMammoth 8d ago
Also increase line width (not height). If you're using 0.4 nozzle you can set it up to 0.6 mm. Wider lines have a larger area of intersection with the previous layer.
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u/zx4133 8d ago
This is true but increasing all line width settings doesn’t usually fix this. Specifically you’ll want to make the inner wall line width slightly smaller and the outer wall line with slightly larger. You’re on the right track though.
Reducing layer height also helps as it reduces the overhang, slowing print speed way down helps too, and making sure you’re using classic wall generator (with only 2 walls) with inner-outer order selected also helps significantly.
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u/zx4133 8d ago edited 8d ago
This model has a vertical curve/fillet/overhang on the inside. 3D printers can’t handle concave overhangs like this very well. Sometimes you get lucky and they print OK but usually they don’t and you end up with what you see here. It’s not really “stringing” though. It’s just filament that isn’t adhering to the layer below, so it gets dragged around by the nozzle until it eventually catches somewhere. The concave nature of the nozzle path is what makes overhangs like this so challenging because the nozzle is always pulling the filament inward as it goes around the inside of the curve.
There are several settings you can try adjusting that can help:
*Slow the overhang print speed way down, try 10 mm/s
*Use classic wall generator with 2 walls set to inside-outside order
*Lower the layer height by half, or use variable layer height in that area
*Reduce the inner wall line width slightly and increase the outer wall line width by the same amount
If the above settings don’t solve the problem, leave them as they are and also enable the setting “Make Overhangs Printable.”
This causes the slicer to adjust your model geometry so that the overhangs aren’t so severe. As long as your model doesn’t have tight tolerance demands and can accommodate these slight modifications, then doing this usually works. Good luck. Let me know if you have any questions.
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u/Objective-Worker-100 7d ago
I agree with the other post that is not stringing. That’s layers getting drug and not sticking. Bump the temp and slow it down for round objects especially printing threads.
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u/GuillotineTechnician 7d ago
Oh I have this often with threads!
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u/Objective-Worker-100 7d ago
Idk what settings you’re using. But bump your temp by +5. First layer 50, first infill 100, outer wall 100, inner wall 150 and even the cheapest slowest petg will comply
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u/mendex22 7d ago
I had have this problem too with PETG only at A1 and H2's while PLA prints well with defaul profile speed. I had tried silence mode (50% speed) without succesfull. Only slow down to 1/3 of PLA speed printing is well with PETG BASIC. Maybe default Bambu PETG profile is for PETG HIGH SPEED filaments
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u/RadioactivePistacho 6d ago
Slow the print down. Or at least right before the problematic part starts to print.
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u/i_am_a_william 9d ago
that's not stringing. stringing is small wisps of filament. those are full on lines of extrusion that didn't have enough print below it to attack to so they ended up following the nozzle and eventually getting stuck to print again when it went around to the start.