Extruder Grinding Solution: Filament Chewing Causes and Step-by-Step Fixes

In this article, we present a complete extruder grinding solution guide. If you hear that familiar click-click-click sound from the extruder mid-print and notice the filament is being advanced but not coming out of the nozzle, the issue is most likely extruder grinding (filament chewing). In this article, we explain step by step why the extruder gear shaves off the filament’s surface, which settings cause this problem, and most importantly, how to fix it.

What Is Extruder Grinding?

The drive gear on the extruder pushes the filament toward the hotend, but if it applies too much pressure, it eats into the filament’s surface. As a result, the gear spins in place, the filament cannot advance, and the print fails halfway. If left unnoticed, plastic shavings accumulate on the gear, which can also lead to extruder clogging.

Grinding is most common with these filaments: soft TPU (struggles to grip the gear), carbon fiber reinforced filament (its abrasive nature wears down the gear and hotend inlet), and moisture-absorbed PLA/PETG (steam bursts increase resistance).

7 Possible Causes and Their Solutions

1. Nozzle Temperature Too Low

If the filament doesn’t melt properly inside the nozzle, the extruder applies excessive force to push it through. For each material, start at the mid-range of the manufacturer’s recommended temperature rather than the lower limit. 210–215 °C for PLA and 235–245 °C for PETG are generally safe starting points.

2. Clogged or Partially Clogged Nozzle

When debris narrows the nozzle opening, filament flow resistance increases and the extruder gear starts slipping on the surface. First, try cleaning the nozzle with a cold pull. If that doesn’t work, replace the nozzle. Regular nozzle inspection is essential, especially when using carbon fiber and metal-filled filaments.

3. Worn Extruder Gear

Regular use of abrasive filaments (carbon fiber, glitter, glow-in-the-dark) can wear down brass gears within just a few spools. Shine a light on the gear surface and inspect: if the teeth look flattened or their sharp edges are gone, it’s time for a replacement.

4. Filament Tension Adjustment (Idler Pressure)

The spring-loaded arm on the extruder must provide the right pressure for the filament. If it’s too tight, it crushes soft filaments; too loose, and the gear can’t grip. Optimum for PLA/PETG: when you pull the filament from the back, the gear marks should be faintly visible but there should be no shavings on the surface.

5. Retraction Distance Too Long

5–7 mm retraction is normal for Bowden systems, but the same distance causes the filament to wear back and forth under the gear on direct drive systems. On direct drive, limit retraction to 0.5–2 mm. Also try lowering retraction speed to the 30–45 mm/s range.

6. Cooling Fan or Heat Creep

Heat creep causes the filament in the upper section of the hotend to soften prematurely. Softened filament gets crushed under the gear and feeding stops. On PLA prints, make sure the hotend cooling fan is running at 100%. If the fan is faulty or clogged with dust, replace it.

7. Filament Moisture

Moist filament creates steam inside the nozzle, causing bursts and resistance fluctuations. The extruder responds to this fluctuation with grinding. If you’re unsure, dry the filament at 50 °C for 4–6 hours and try again.

What to Do Immediately When You Notice Grinding?

Stop the print and remove the filament from the extruder. Brush the plastic shavings off the gear. Check the nozzle and perform a cold pull. To determine which cause is at fault, go through the list above one by one. If you’re unsure, send us your part using the instant price calculator option, and we’ll produce it with the right material and settings.

Regular extruder maintenance is the most reliable way to prevent grinding. With gear cleaning, nozzle checks, and proper storage conditions, you can extend the life of your printer. For abrasive filaments, you can also opt for our engineering materials printing service and avoid the hassle of extruder wear.

For more maintenance tips, check out our extruder maintenance and drive gear cleaning guide.