Material is ground down by the feeder

When material no longer comes out of the nozzle and dust is visible in the feeder, it means that the filament has been ground down. The filament that has passed the feeder may appear flattened and the knurled wheel of the feeder may have dug into it. When this happens, the feeder won’t be able to forward the material anymore and will continue to grind the filament. This situation can get worse, as the ground material will eventually end up in the Bowden tube, causing extrusion problems. Therefore, it’s important to remove the filament as soon as you notice that it has been ground down, and to properly clean and check the feeder. Read this page to find out how.


Removing the filament

Firstly, it’s important to remove material that has been ground down by the feeder. To remove it, use the following procedures for unloading/changing material:

  • Ultimaker S5 and Ultimaker S3: On the Ultimaker S5 and Ultimaker S3 this is less likely to happen, since the flow sensor will prevent further grinding of material in the feeder. When there is still an issue with the filament, this is easy to fix. Release the feeder tension by lifting the lever at the side of the feeder. This will create extra space in the feeder, allowing the material to be easily moved through it.
  • Ultimaker 3 (Extended): Go to ‘Material/PrintCore’, select ‘Material 1’ or ‘Material 2’, then ‘Unload’
  • Ultimaker 2(+) family: Go to Material > Change in the printer menu. The material will be rewound
  • Ultimaker Original(+): Go to Control > Temperature > Nozzle, then set the temperature. Open the feeder and remove the filament manually

The filament may not completely rewind, due to the ground part in the feeder. To resolve this issue, gently pull on the filament when removing it. This will allow you to put extra force on it and will help the knurled wheel of the feeder get a grip on the material again. With the Ultimaker 3 (Extended), Ultimaker 2+ and Ultimaker 2 Extended+ you can also release feeder tension by lifting the lever at the side of the feeder. This will create extra space in the feeder, allowing the material to be easily moved through it.


If the material breaks during removal, or it’s impossible to extract, additional action is required:

  1. Cut the filament under the feeder, so that just a small piece remains
  2. Remove the feeder clamp clip
  3. Loosen the Bowden tube by pressing on the tube coupling collet and pulling the Bowden tube out
  4. Pull the piece of the filament (sticking out at the bottom side of the feeder) from the top side of the feeder. Remove any small pieces of filament left in the feeder with tweezers
  5. Now you should be able to remove the filament from the Bowden tube. Ensure the nozzle is heated whilst the material is still in the hot end

Cleaning the feeder

Once the ground down material has been removed, it’s likely some filament debris will be left in the feeder. To prevent any particles entering the Bowden tube and hot end while moving along with the filament, it’s important to clean the feeder before continuing. This can be done by blowing the particles out of the feeder or using a small brush (e.g. a toothbrush) to clean it. For the Ultimaker Original(+), you can remove the knurled wheel from the feeder and clean it completely. To find out how to do this, click here.


Note: If there are any small particles in the Bowden tube, this must be cleaned too. Here’s a guide explaining how.

Cleaning the nozzle / print core

Some degraded material could be present in the print core that prevents good extrusion and therefore causes grinding of the filament in the feeder. This especially occurs when the grinding was found out late and material is heated in the nozzle without movement for prolonged time. In this case, the nozzles or print cores should be cleaned internally. This can be done with hot and cold pulls. More information of this procedure can be found in this page.

Checking the feeder tension

After cleaning the feeder, it’s important to check the tension. All Ultimaker 3D printers have a feeder that works with a spring mechanism to put tension on the filament. During normal use the default feeder tension should not cause any problems, but if you change the feeder tension and set it too high, it may flatten and eventually grind the filament that passes through. Reset the tension of the feeder by turning the bolt in the top of the feeder, until the indicator is at the middle mark.


Checking the material

When using materials that easily absorb moisture (e.g. PVA) it’s important to check the filament before printing. If a material like PVA absorbs too much moisture it will become soft and malleable/pliable and in some cases, even sticky. This may prevent the printer from forwarding the material, which can lead to feeder grinding. If this occurs, replace the material with a new, correctly stored spool to resolve the problem.

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