Grinding filament is never welcome and not what you want to see but keep reading on how to spot and fix the issue.
Signs the extruder is grinding filament:
The picture on the left shows a section of filament after it was manually pulled out of the extruder. You can see the dent where the drive gear dug in deep into the filament, making further transport of this filament impossible. It had to be removed manually with a bit of force.
Explanation:
This usually happens when the pressure inside the HotEnd gets too high or if there is anything blocking filament transport. 3D printer filament grinding can be caused by a number of different things, read our ‘How to fix:’ section to learn more.
How to fix:
Deformed filament or filament diameter too thick
Use good calipers or a better yet a micrometer screw gauge to measure the diameter of the filament coming of the spool and check if it is round or has been flattened. If it is thicker than it should be or no longer perfectly round, return the spool to the manufacturer/seller for a replacement. Cheap filaments often have large fluctuations in their diameter.
Filament not unspooling from the spool, kinked, knotted or twisted on the spool
You may be able to see the issue and untangle the knot or remove a layer or two if there is a kink. If you cannot see the issue but your spool will not unspool easily, or it is repeatedly happening, please see our article [How to untangle a tangled or knotted spool].
Too much friction in filament path (especially common with worn or dirty Bowden tubes)
Check the filament path is clean, especially if using a Bowden tube. If your Bowden tube or another part has become worn it may need replacing.
Trying to extrude too much material for the nozzle size
Calibrate your extruder and reduce your material flow. Especially when switching to smaller nozzle sizes your extrusion settings need to be spot on. The smaller diameter holes are way less forgiving as we’re facing higher pressure trying to extrude through a smaller hole to begin with. Too much pressure and the drive gear of the feeder motor is likely to start grinding instead of pushing the filament.
Partial (or full) clog in the nozzle or HotEnd
See [Clogged Nozzle].
The nozzle being too close to the bed (bed levelling is off) or too close to the previously printed layer (warping)
See [Nozzle to close to the bed] and/or [Warping].
Trying to print too cold
Check the temperature range of the filament you’re printing. Increase your printing temperature gradually in 5°C increments within the range, staying around 10°C below the glass transition temperature (for rigid.ink, find GT temp in the downloadable datasheets in the settings tab on product pages).
Trying to print too fast
Printing too fast, if you haven’t adjusted other settings to allow for the extra speed, can cause issues such as not being able to feed the filament fast enough. Try reducing your speed in 10mm/s increments until it feeds correctly.