What is a Mouse Bite and how do I fix it?

TROUBLESHOOTING- What is a “Mouse Bite” and how do I fix it? (Clogged Nozzle)


Often times a clogged nozzle is nothing more than a “mouse bite.” This Solution will show how to identify a “mouse bite” and fix the issue. You will need a set of wire or plastic cutters for this process.


1) Preheat the machine to the proper temperature for the material you are using. (ABS 240, PLA 220, etc.)

2) Using wire or plastic cutters, cut the material off just below the extruder assembly. Remember not to let the material unravel as it will be difficult to respool.

3) Open the extruder assembly and pull the material out of the hot end. You will now be able to locate the “mouse bite.” It will look like a small notch taken out of the filament by the hobbed extruder bolt. Pull the filament all the way out of the machine and proceed to step 4.



4) After removing the old filament, reinsert the fresh section of filament into the extruder assembly. Close the assembly and begin printing.

Future Prevention:

There are a few different possible causes of the “mouse bite.” Make sure to check each of these in order to prevent a “mouse bite.”

  • Hot end temp too low: If the nozzle temp is too far below the required extrusion temperature for the material loaded, then a mouse bite can occur when trying to feed. Make sure the nozzle is at the proper temperature for the material you are trying to extrude.
  • Bed too close to the nozzle: If the bed is too close to the nozzle, then the material will not be able to exit the nozzle. This blockage can cause a mouse bite. Make sure the bed is far enough away from the nozzle by using the z adjust screw.
  • Filament catching on the spool: If the filament spool is cross threaded or becomes stuck, then a mouse bite will likely occur. Make sure not to let filament unspool as respooling it can easily cause a cross thread. Make sure there is nothing touching the spool so it can spin freely on the spool minder.
  • Improper settings selected: Improper temperature, speed, fan, or retraction settings can easily cause a mouse bite. Make sure the proper settings have been used for the material you are printing with.
  • Incorrect filament diameter:  Ensure your filament is the proper diameter (2.85mm +/-0.1mm). If the filament is too large in diameter, it will cause feeding issues resulting in a mouse bite.
  • Hot end not fully purged: If the hot end has not fully purged from the previous material, it can cause feeding issues and mouse bites. Though this will only happen if the previous material was a higher temp, it is still good practice to fully purge.
  • Dirty extruder assembly: Make sure the extruder assembly is clean and free of dust and debris. If there is excess filament shavings, the bolt can skip when feeding material.

If this does not solve your issue or you were not able to identify a mouse bite, please feel free to ask us any questions by opening a New Ticket. We would be more than happy to assist you with getting your machine back up and running.

in Troubleshooting