Fiber Jam Detection




  • 10mm torque wrench
  • Tweezers


Note that the print head is factory-calibrated; do NOT adjust or disassemble in any way unless specifically instructed to do so by Markforged Support. Warranty claims for assemblies that have been adjusted, disassembled, or modified may not be honored.


Automatic fiber jam detection is enabled by default. We recommend that you enable fiber jam detection so that, in the event of a fiber jam, your printer will be able to prompt you to take appropriate action.

Troubleshooting a Fiber Jam

The most common causes of a fiber jam are as follows:

Extruder Jam

This failure is most common when printing with Kevlar. If the part has a high volume of Kevlar, the repeated use of the fiber cutter (many times per part layer) increases the likelihood of extruder jams. Due to its flexibility, Kevlar tends to bend or break more frequently than the other fiber materials, and can become caught in the extruder. 

Nozzle Jam as a Result of Incorrect Fiber Nozzle Height

A fiber nozzle set to the incorrect height can cause the nozzle to jam, along with other print issues. Fiber jams due to poor leveling are most common when printing with Carbon Fiber. Carbon Fiber is thicker than the other fiber materials, and requires extra care when leveling the fiber nozzle.

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Enable / Disable Fiber Jam Detection 

  1. Select the menu icon from the dashboard.

  2. Select the Settings tile from the available options.

  3. Select the System Info tile from the available options.

  4. Select the gears icon from the row of icons at the bottom of the screen.

  5. Enable or disable the automatic jam detection as needed by toggling the Fiber Jam Detection switch.

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Detect and Debug Fiber Jams

In the event of a suspected fiber jam, your printer will stop the print to allow you to resolve the issue. Once a jam is detected and corrected, the print can resume from where it stopped.

    1. Select Debug Jam button on the touchscreen.

    2. Clear any excess fiber from the nozzle and ensure that the print bed has clearance to lower completely, then press Next.

    3. Wait for the nozzles to cool completely.

    4. Use the 10mm torque wrench to unscrew the fiber nozzle and check the nozzle for any obstructions, then press Next to continue debugging.

    5. Remove the fiber Bowden tube from the print head and verify that there are no obstructions in the print head’s fiber nozzle channel, then press Next to continue debugging.

    6. Verify that the material on the fiber spool is neither tangled nor becoming unspooled, then press Next to continue debugging.

    7. Verify that the fiber is not caught in the Bowden tube and press Next.

    8. Ensure that there is nothing in the way of the print bed and print head returning to their pause positions.
      Note: You should always remove foreign objects from the print chamber before initiating a print job.

    9. Follow the onscreen prompts to return to the pause screen on your printer.

Ensure that you reinstall any components you removed during this procedure before attempting to print.


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