Spaghetti
The print detaches and the printer keeps extruding into air — producing a tangled mess of filament. The most wasteful failure mode.
Critical severity
Structural
What It Is
The print detaches and the printer keeps extruding into air — producing a tangled mess of filament. The most wasteful failure mode.
How It Forms
This is always a secondary failure. Something else goes wrong first:
- Adhesion failure — Part lifts off the bed. Printer doesn’t know, keeps printing in empty space.
- Support failure — A support structure breaks. The feature it was holding collapses. Printing continues above the collapsed area.
- Part knocked by nozzle — Over-extrusion or warping creates a bump. Nozzle catches it, knocking the part loose.
- Layer shift + crash — A severe shift causes the nozzle to collide with the part, breaking it free.
The printer has no feedback — it follows the G-code toolpath regardless of what’s actually on the bed. It deposits filament into air, which curls and tangles into the characteristic “spaghetti” mess.
On a long print, this can waste hours of time and meters of filament before anyone notices.
Visual Signature
- Unmistakable — tangled mass of filament on or around the bed
- No recognizable print shape
- Often wraps around the hotend or nozzle
- Filament may fuse to the heater block (difficult cleanup)
Root Causes
| Cause | Calibration Variable | Direction |
|---|---|---|
| Adhesion failure (upstream) | Z-Offset, Bed Temp, Bed Mesh | various |
| Warping dislodging part | Bed Temp, Cooling | various |
| Support structure failure | — (slicer) | — |
| Nozzle collision from over-extrusion | Flow Rate, E-Steps | ↑ |
| Layer shift causing crash | Max Accel, Belt Tension | various |
How the Auto-Tuner Detects It
- Camera: The #1 use case for anomaly detection. Compare current print outline to expected shape. If the outline doesn’t match or disappears → spaghetti in progress.
- Encoder: If flow is being deposited but camera shows nothing being built → printing into air.
How the Auto-Tuner Fixes It
- Prevention: All calibration reduces spaghetti risk by preventing its upstream causes.
- Live tuning: Anomaly detection catches it within seconds and pauses the print. This alone justifies the entire camera system — one saved 8-hour print pays for the hardware.