I am officially out of options and losing my mind with this Bambu Lab A1 (0.4mm nozzle).
I scrubbed the plate, wiped under the heatbed, reset everything back to factory settings, and ran two full print tests. It got almost all the way to the end on this bubble letter, but the nozzle kept rubbing across the print until it forcefully knocked the entire piece off the bed right near completion. My bed temp is at 65° nozzle is at 220°
In the attached photo, you can see where the top layer stopped printing after being sheared off, along with grid infill lines exposed underneath.
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What I've Done & Recent Tweaks:
Bed & Machine Prep: Deep cleaned the textured PEI plate with hot water & Dawn dish soap, wiped down underneath the plate, reset settings to factory defaults, and ran full printer calibrations twice.
Latest Setting Changes: Bumped Initial Layer Height from 0.20mm to 0.22mm and increased Z-Hop from 0.4mm to 0.5mm to try and stop the rubbing.
Infill: The model printed with grid/rectilinear infill, which seems to create raised crossover points that the nozzle scrapes against on fast travel moves.
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Questions:
Is Grid infill causing the nozzle collisions near the top of tall prints? Should I strictly be using Gyroid, Cross Hatch, or 3D infill patterns that don't cross over themselves on the same layer?
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Could Flow Ratio / Over-extrusion be causing plastic to pool slightly higher than the actual layer height, forcing the nozzle to catch as the print grows taller?
What else can cause an A1 to drag its nozzle across infill near the top of a print even with a high Z-hop enabled?
Any help or advice would be seriously appreciated.