How to Fix an Extruder That Clicks or Grinds Filament

An extruder that clicks, ticks or grinds is telling you that the motor is being asked to push filament that will not move. The click is the stepper skipping, and grinding is the gear shaving a flat spot on the filament. The cause is almost always resistance somewhere between the gear and the nozzle tip, or a gear that cannot grip.

This guide is built from manufacturer documentation (Prusa and Bambu Lab) and standard practice. Treat temperatures and speeds as starting points and check your own printer's manual.

Quick symptom table

1. Check the temperature and the speed

Filament that is not fully melted pushes back hard. Confirm the nozzle temperature matches the filament's printed range. Prusa's extruder noise guide suggests increasing hotend temperature by 5 to 15 °C if grinding occurs, and using the latest slicer and current filament presets.

Speed matters as much as temperature. Bambu Lab's clog guide notes that at very high speeds filament spends too little time in the hot zone to melt fully, and recommends reducing print speed or raising the temperature slightly. A hotend can only melt so much plastic per second, so thick layers, wide lines and fast moves together can demand more than it can deliver. See our guide to print speed versus quality for the trade-offs.

2. Look for a clog

A partial or full clog raises the resistance until the gear cannot overcome it. Prusa lists a clogged hotend as a cause and says to clean or replace it. Bambu Lab describes a simple test: with the nozzle at 220 °C and PLA loaded, extrude by hand. If the filament drops straight down, is relatively long and looks smooth, the nozzle channel is clear. A short, rough strand points to a narrowed channel or a faulty drive gear.

Fiber-filled filaments leave particles in the nozzle over time. Bambu recommends a 0.6 mm or 0.8 mm nozzle for these materials and says a 0.2 mm nozzle dramatically increases blockage risk. Our clogged nozzle guide covers clearing methods, and nozzle sizes explained helps you pick a size.

3. Rule out heat creep

The heat creep guide covers causes and fixes in more detail. If the printer prints normally for a while and then starts clicking, heat creep is a strong suspect. This is when heat climbs too far up the hotend, softens filament above the melt zone and lets it swell and jam. Prusa's guide on extrusion stopping mid-print lists these contributing factors:

• Ambient temperature above 35 °C (30 °C for some filaments).
• Insufficient airflow over the heatsink, including a dusty heatsink or a failing fan.
• A hotend temperature set higher than needed.
• Printing very thin layers so little filament flows to carry heat away.

Prusa's suggestions include cleaning dust from the heatsink, lowering the heatbed temperature by 5 or 10 °C, using a layer height of 0.15 or 0.20 mm, and unloading filament while the hotend is still hot after a print.

4. Check idler tension and gear alignment

The gear needs to grip without crushing. Prusa notes that idler screws must be balanced: if too loose the motor skips, and if too tight the gear teeth can grind the filament. Follow your printer's manual for the correct setting rather than guessing.

Prusa also says to verify that the extruder gears align with the opening above and the PTFE tube below, and that the motor shaft gear is tightened by its grub screw against the flat of the motor axis. If you run a Bowden setup, the longer tube adds friction, so a kinked or worn tube is worth checking.

5. Clean the drive gear and filament path

Shaved plastic packs into the teeth and the gear stops biting. Prusa's guide says to clear buildup with pliers or a durable pin and make sure the gears turn freely. Inspect the PTFE tube for debris. Remove the filament and trim any section that is flattened, chewed or abnormal in diameter, as Bambu advises for locally thick or thin filament.

Very soft filaments such as TPU 85A, and moisture-affected PVA, can be flattened by the drive gear, according to Bambu. Wet filament in general prints poorly, so dry it if it crackles or looks fuzzy. A spool that cannot turn freely or is tangled will also stall the feed, so check the path from the spool.

6. Confirm the first layer is not too close

If the nozzle is pressed too hard against the bed there is nowhere for plastic to go. Prusa lists first layer calibration as a cause because an incorrect nozzle height can build excessive pressure. Redo the calibration and see fixing a bad first layer.

Confirm the fix

Heat the nozzle, extrude 50 to 100 mm by hand and watch the strand. It should flow steadily with no clicking. Then print a small calibration object and listen during the first layer and again after 30 to 60 minutes, since heat creep only appears once the hotend has been running a while. If clicking returns, work back through the list and change one thing at a time.

Clicking that keeps coming back usually means a worn part such as the gear, heat break or tube. Replace it using the manufacturer's instructions. For routine care, see our maintenance checklist.

Using a Bambu Lab AMS? A failed feed from the AMS is a different fault, covered in fixing a Bambu AMS jam.