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Heater band

The G1 extruder has three independent heater bands, one per heating zone. Each band is a resistive heating element that clamps around the outside of the barrel — it is not a cartridge inserted into a bore — and heats its zone to the target temperature.


ParameterValue
Voltage220V — mains, switched by a relay on the extruder_board
Power300W each
Inner diameter40 mm
Height35 mm
Quantity3 — one per heating zone

The same zone has three names depending on where you are looking:

ZoneBandIn Ginger SlicerOn the display / in KlipperLocationRole
Feeding ZoneT0Zone 1extruderFirst band — where material entersPre-melts pellets entering the screw
Melting ZoneT1Zone 2extruder1Middle bandMain melting
Nozzle ZoneT2Zone 3extruder2Band nearest the nozzleFinal conditioning before extrusion

The printer’s temperature screen lists them as Extruder / Extruder1 / Extruder2, alongside Heater Bed.

Each band is paired with a thermistor (NTC 100k) for closed-loop temperature control. See Temperature sensor disconnected for sensor-specific issues.


Start by identifying which error the printer reported — the cause is different for each.

”Below minimum extrude temperature” — with a plausible temperature

Section titled “”Below minimum extrude temperature” — with a plausible temperature”

Klipper shuts the machine down if the barrel falls below the minimum extrude temperature. If you are printing a material at 160°C and the limit is also set to 160°C, a small dip is enough to trigger it.

  • The limit exists to stop the machine extruding while cold
  • It can be lowered in the firmware configuration if your material genuinely runs that low

”Below minimum extrude temperature” — with a negative temperature

Section titled “”Below minimum extrude temperature” — with a negative temperature”

A reading that has gone negative is always a sensor wiring fault, never a heater fault. An open connection reads as very high resistance, which the firmware interprets as an extremely low temperature.

Check every connection from the sensor back to the Octopus in the control panel, in order of likelihood:

  1. The JST immediately after the sensor — the most common culprit
  2. The JST on the Octopus — the second most common
  3. The ethernet cable carrying the signal

How to test it: bring the zone up to temperature and watch the temperature graph while you gently move things — first the ethernet cable, then the JST connectors of the sensor under test. The reading must stay stable while you move them. Any fluctuation on the graph identifies the faulty connection.

”Not heating as expected” — graph looks clean but temperature does not climb

Section titled “”Not heating as expected” — graph looks clean but temperature does not climb”

Each heater has its own relay, soldered inside the panel box on the extruder_board. If that relay is not switching, the band cannot draw power.

What you observeCause
The band warms slightly, then stopsThe relay is faulty
The band does not warm at allThe band itself has failed and needs replacing

The relays are soldered to the board — contact Ginger Additive support. This is not a field repair.

Klipper shuts down when the cooling fans run (older machines)

Section titled “Klipper shuts down when the cooling fans run (older machines)”

On some older G1 versions the sensor of the last band (T2, nearest the nozzle) has no Kapton insulation around it. The part-cooling fans then blow directly onto the bare sensor and over-cool it: the reading drops faster than the heater can compensate, and Klipper triggers a safety shutdown.

See also Temperature sensor disconnected.


Most apparent band failures are actually connector or sensor issues — work through Troubleshooting a temperature fault first.

The bands come off downward, over the nozzle end of the barrel: raise the extruder at least 10 cm above the bed, power off at the mains, remove the insulation and the sensors, undo the 2 screws clamping each band, and slide it off from below. Refit the new band with its cables in the same position.

Full steps: Heater band replacement.