The print came loose from the bed mid-print and the printer continued extruding into air, filling the build volume with a tangled pile of filament. You come back to the printer and find no recognizable part — just stringy plastic everywhere.
Understand the Two Failure Modes
Mode 1 — Bed detachment: The print lifts off the bed entirely. Usually happens in the first 30 minutes or when a large-footprint print warps. The fix is in first layer and bed adhesion settings.
Mode 2 — Nozzle collision: The print partially warps or has a failed section that rises into the nozzle path. The nozzle hits it, knocks the print loose, and spaghetti follows. The print may have been adequately bonded to the bed, but a protruding section got clipped.
These need different fixes. Look at the failure: if there’s filament residue on the bed showing the print was once there but lifted, it’s mode 1. If the print is still partially attached to the bed but has a section knocked over, it’s mode 2.
Preventing Mode 1 (Bed Detachment)
Bed detachment traces to the same causes as any adhesion failure. Fix in this order:
- Clean the bed with IPA before every print
- Calibrate Z-offset — first layer must have proper squish
- Match bed temperature to material: PLA 60°C, PETG 75–80°C, ABS 105°C
- Add a brim — for any part with corners, small footprint, or tall height relative to base area
For ABS and ASA: add an enclosure. These materials can’t maintain bed adhesion without controlling the thermal environment.
Preventing Mode 2 (Nozzle Collision)
Enable Z-hop (0.2–0.4mm) on travel moves. The nozzle lifts before traveling, which prevents it from dragging across slightly warped or protruding sections. This doesn’t add significant print time but eliminates the most common collision scenario.
For ABS and tall prints: eliminate corner lift with a brim wide enough to anchor the perimeter. A 10–12mm brim on ABS prevents the corner curl that creates the obstruction.
Print Failure Detection
For long prints (overnight, multi-hour), a webcam with failure detection software (Obico, formerly “The Spaghetti Detective”) monitors the print and sends a notification or pauses when it detects abnormal stringing or detachment. This prevents wasting 10+ hours of filament on a failed print you didn’t catch early.
What Doesn’t Help After the Fact
There’s no fixing spaghetti mid-print — stop the printer, remove all debris, and restart with adhesion improvements. Small pieces of filament left on the bed will get knocked around by the nozzle and ruin the next print. Clear everything, clean the bed, and start over.