Filament Extrusion Issues


Extrusion issues can manifest in a variety of ways, with several different causes. With a little troubleshooting and patience, they are usually easy to remedy. We have compiled some tips for solving some of the more common extruder problems to get you back up and printing. 

Before proceeding, please collect and record the following data: 

  • Gigabot number
  • Pictures or videos of your issue
  • .factory file
  • Filament type
  • Are you using a filament cleaner?
    • Do NOT use the filament cleaner when printing with PETG due to elevated risk of it being pulled into the filament detection sensor.
  • Is the hot end leaking plastic above the nozzle or heater block?
  • Are you able to manually feed filament through the hot end? To do this, follow these steps:
    1. Heat the hot end to 210C for PLA
    2. Depress the push fit connector where the filament tube meets the extruder body and take out the filament tube
    3. Insert 2.85mm PLA filament through the extruder body and into the hot end
    4. Grip the filament with your hand above the extruder body, then attempt to force it through the hot end.
      1. Is anything coming out of the nozzle orifice? If no, this is a sign of a clogged hot end. Please follow these steps to attempt to remove the blockage: Performing a "Cold Pull"

A note on printing with PLA filament:

Setting the nozzle to temps higher than 220°C (just above PLA's glass transition temperature) when using PLA or leaving PLA filament in a heated nozzle without printing can cause the polymer to degrade and carbonize. This will create nozzle clogs that are difficult, if not impossible, to remove. When using PLA, ensure that the temperature does not exceed 220°C, and do not let the filament sit in an idle heated nozzle for extended periods of time. These practices apply for all filaments just above their glass transition temperatures as well.


Jump to: Filament GrindingNo filament extruding from hot endInconsistent Extrusion

Filament Grinding

This occurs when the filament is unable to pass through the nozzle, resulting in the extruder drive gear shredding the filament instead of feeding it into the hot end. You should clean up after this failure by following the instructions in this video: Cleaning Extruder after Filament Grinding

Possible Causes: 

  1. Plastic shavings in extruder drive gear teeth
  2. Printing materials with lower print temperatures in an enclosure.
  3. Using an outdated or incorrect printing profile. 
  4. Filament Filter stuck in filament detection sensor.
  5. Too much resistance is present in the filament tube.
  6. Inadequate tension settings on the extruder body.
  7. Hot end clog
  8. Extruder drive gear not installed correctly
  9. Inconsistent filament diameter

Possible Solutions:

  1. Make sure that the teeth of the extruder drive gear are clean of plastic shavings prior to starting the print so the teeth fully bite into and grip the filament so it can be forced through the hot end. You can do this with a wire bristle brush, pointy tool, and compressed air as discussed in this video: Cleaning Extruder after Filament Grinding
  2. Remove one or more panels from your Gigabot's enclosure.
    1. Some materials have a lower temperature threshold. PLA, PVA, and some wood or metal-filled materials do not require high heat settings when printing. A high ambient temperature within an enclosure can soften these filaments too much, making it impossible for the drive gear to catch the filament to feed it through the extruder. Removing one or more panels from your enclosure will ensure the ambient temperature stays cool enough for these materials.
  3. Verify you are using the correct and most up-to-date software profiles for your Gigabot.
    1. Your Gigabot model, firmware version, and hardware determine which profile you need to use. 
  4. Read this article about filament tube issues to determine if one of them may be the cause of the extrusion issues: Excessive Filament Tube Friction
  5. Verify that the filament is not bent in a way that would impede its progress through the tube. 
  6. Verify that the tensioner nuts are properly set
    1. The force of the bearing pressing against the filament allows the extruder motor drive gear to grip the filament and push it through the hot end. It is critical that the screws are properly set to apply adequate force to ensure proper extrusion. 
  7. Use a piece of filament to check that it can travel smoothly through the filament detection unit.
  8. Ensure that the filament filter is not getting caught in the filament detection unit. We have seen a few instances of the filament filter dust cloth getting pulled into the filament detection unit which halts the travel of the filament and therefore grinds through. To prevent it from getting pulled in, you should set the dust cloth to be below the top of the spiral wrap, and then snip off the point of the spiral wrap to prevent that from getting lodged in the detector as well. Here is a photo: 
  9. To fix a hot end clog, please do the following:
    1. Perform cold pulls in the hot end to remove any clogs as shown here: Performing a "Cold Pull"
    2. If the cold pull does not work, please order a new hot end (Link to Shop) and then install it using the following instructions for your hot end: 
  10. The extruder drive gear needs to be installed correctly for it to properly grip the filament and force it through the hot end
    1. The filament drive gear is the toothed metal cylinder that is attached to the extruder motor which grips and forces the filament through the hot end. The teeth of the drive gear are formed by cutting notches into the edge of the steel cylinder. This forms crescent shaped teeth. The drive gear teeth should be opened up towards the filament as shown below for it to get the grip it needs to force the filament through the hot end.
      1. filament_drive_gear_teeth.jpg
      2. The left and right extruder motors have drive gears that face opposite directions. To fix the issue of a drive gear facing the incorrect direction, you will need to switch the motor out for a motor with the drive gear facing the correct direction. You may also use a 2mm allen wrench to loosen the two set screws that attache the filament drive gear to the extruder motor shaft, then turn the drive gear 180degrees so that it is facing the proper direction, apply Loctite to the set screws, align the drive gear teeth so that it is directly opposite the middle of the idler bearing in the tensioner arm. This ensures that the teeth will be in the direct path of the filament when it is inserted so you get proper engagement of the teeth. Lastly, retighten the set screws onto the flat of the motor shaft to anchor it in place.
  11. Inconsistent filament diameter can prevent extrusion of the plastic. The filament needs to measure 2.85mm plus or minus 0.1mm in order to fit through the hot end. Please measure the diameter of the filament at 5 different places along a length of 1 meter to check for improper diameter. If found, please email a photo of the filament being measured by an analog caliper or micrometer.

If you are still experiencing difficulty after performing these steps, please contact re:3D Support or open a support ticket and include the following information:

  1.  A photo of the back of the Gigabot
  2.  A close-up photo of the filament detectors
  3. A photo of where the filament tube(s) connect to the print head

No Filament Extruding from Hot End 

If no filament is extruding from the hot end, it may be due  to one or more of the following causes: (Filament grinding may or may not be present)

Possible Causes: 

  1. The hot end cooling fan is not working (GB3/3+ or GB2 with All Metal Hot End upgrade).
  2. The hot end is too cold for the filament or print speed you are using.
  3.  The nozzle is clogged.
  4.  The J head PTFE liner has swelled (GB2).
  5. The extruder gearbox is defective.
  6. The nozzle is loose from the extruder assembly. 

Possible Solutions: 

  1. Verify the hot end cooling fan is active when the nozzle temperature is above 50°C.
    1. If the fans do not engage, you may need to replace them. Select GB2 or GB3 fans depending on your Gigabot model. 
  2. Verify the hot end temperature is set to the appropriate temperature for the filament you are using.
    1.  If you are printing at higher speeds, you will also need to adjust your hot end temperature, as the faster moves require faster melting of filament. 
  3. Install a dust filter, or replace a dirty dust filter.
    1. Dust or particulates may be preventing extrusion from the hot end. Using a dust filter or replacing a dirty dust filter will help keep your nozzle free of debris. Periodically check your filament filters to ensure cleanliness. If there is visible dust or debris built up inside, your filament filter needs to be replaced.


  1. If the hot end is reaching target temperature but no filament is extruding, performing a cold pull will most likely remove the clog in the nozzle. Follow the instructions here to do so: Performing a "Cold Pull"
  2. The J head PTFE liner has swelled (GB2).
    1. The J head is rated for about 500 printing hours before the PTFE liner swells. If you are using a J head on a GB2, you will need to replace your hot end within this time frame. We recommend upgrading to the GB2 Metal Hot End. Instructions on this upgrade can be found here
  3. The extruder gearbox is defective.
    1. If the motors within the gearbox are not sufficiently lubricated, it can cause underextrusion. This is a factory defect, and the extruder gearbox will need to be replaced. Contact re:3D Support for assistance. 
  4. The nozzle is loose from the extruder assembly.
    1. If a gap is present between the thermal barrier tube and the nozzle, you may notice filament leaking into the threads. This indicates the nozzle has come loose from the assembly, and the hot end will need to be replaced

If you are still experiencing difficulty after performing these steps, please contact re:3D Support or open a support ticket.

Inconsistent Extrusion

Several factors may contribute to inconsistent extrusion during printing. 

Possible Causes: 

  1. The nozzle is partially clogged. 
  2. Your filament quality may be compromised. 
  3. Inadequate tension settings on the extruder body. 

Possible Solutions: 

  1. If you suspect a clogged nozzle, please refer to the cold pull instructions.
  2. If the filament is old, or has absorbed too much moisture from the air, it will affect the quality of your prints. Try printing with a different material to verify this is the issue. For more information on filament care and storage, please refer to Drying Filament.
  3. Are your tensioner nuts set according to this photo? The nuts should be at least halfway visible in the top window of the extruder body. 
  4. Slowing down the print speed to 3000 mm/min. 
  5. Print with the opposite hot end if your Gigabot has a dual extruder system.
  6. Adjust your layer height. (If the layer height is too small, it can cause inconsistent extrusion.)

If the above solutions do not work, please contact re:3D Support with the following information: 

  1. How many hours have you printed with your hot end and nozzle?
  2. Have you ever disassembled your hot end?
  3. Video of the print in action
  4. Photo of the extruder body (front and top view) 

Questions or concerns? Reach out to our support team at or open a support ticket

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