Clogged print core

If there is no material flowing from the print core for at least 10 minutes it could suggest that there is some burnt material in the nozzle, leading to a nozzle clog. In this case, the print core should be cleaned by performing the below described method. These instructions are specifically written for cleaning a BB print core with PLA material, since PVA is more likely to cause clogs. The method can however also be applied to AA print cores if necessary. Please note that you have to unclog the print core with the last used material (except for flexible materials) and at other temperatures in this case.

Note: Make sure there is no material in the print core when you start this procedure.

Preparing

  1. Place the print head in the front right corner to avoid bending of the XY axles when applying pressure to the material during a hot pull or cold pull.
  2. Go to Material/PrintCore > PrintCore 2 (BB print core) > Set temperature and set the temperature to 230 °C.

    Note: For AA print cores use a temperature that is slightly higher than the printing temperature of the material.

  3. Remove the clamp clip from the top of the print head.
  4. Loosen the bowden tube by pressing on the tube coupling collet and pulling the bowden tube out while doing this.

Removing the clamp clip
Removing the bowden tube

Hot pull

  1. Cut off approximately 20 cm of PLA with a straight cut and try to straighten the material as much as possible.
  2. When the nozzle reaches the target temperature of 230 °C gently insert the piece of PLA into the print head until you feel some resistance.
  3. Hold the piece of PLA with pliers and gently apply pressure to the material for ±2 seconds so that it extrudes from the nozzle or until it cannot be pushed any further.

    Caution: The use of pliers is required to prevent injuries on your hands in case the material breaks.

    Note: Applying too much pressure to the material is almost impossible when the print head is located in the corner. If there is no extrusion, apply more pressure.

  4. Pull the material out with a quick, firm pull once the 2 seconds have passed.

    Inserting material for the hot pull
    Applying pressure during hot pull

  5. Cut off the tip of the filament that you have just pulled out.
  6. Check the color and the shape of the tip of the filament and compare it with the pictures below.

    Hot pull - burned material
    Hot pull - clean

  7. Repeat this hot pull process until no more degraded material is visible on the tip of the filament and the tip of the filament looks as clean as the picture on the right. After completing the hot pull process, manually flush some material through the print core with pliers and take it out again.

Cold pull

  1. Take a new piece of PLA and insert it into the print head by hand until you feel some resistance.
  2. Hold the piece of PLA with pliers and gently apply pressure to extrude some material.
  3. Lower the temperature of the print core to 75 °C. Keep pressure on the material with the pliers until the print core reaches a temperature of 150 °C.

    Note: The slight pressure on the material while cooling down is required to prevent air from entering the nozzle.

    Note: For AA print cores lower the temperature to a temperature of 15 - 20 °C above the build plate temperature.

  4. Wait until the target temperature of 75 °C is reached.
  5. Grab the material with pliers and pull it out with a quick, firm pull. The tip should now look as on the right picture.

    Cold pull
    Cold pull

Re-assembly

  1. Insert the bowden tube into the print head.
  2. Re-attach the clamp clip and keep pressure on the bowden tube while doing this.

Inserting the bowden tube
Placing the clamp clip

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