This solution goes over what a mouse bite is, potential causes of mouse bites, and how to fix them. 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. Check the filament for a small notch taken out of by the hobbed bolt. This is what we call a mouse bite. 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.
Here are a few potential causes of mouse bites:
- Hot end temperature too low: If the nozzle temperature is too far below the required extrusion temperature for the filament loaded, then the filament will not melt. The solid filament will not be able to extrude through the nozzle, which will cause the hobbed bolt to grind a mouse bite into it. 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 (2.85 ±0.1mm). If the filament is too thick, 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. More information on cleaning out the hot end here: Cleaning the Hot End and Nozzle
- 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.