If material does not flow consistently, the nozzle could be clogged with degraded material. In this case, the nozzle should be cleaned by performing the hot and cold pull method. You can use cleaning filament or PLA for this.

Cleaning filament can be used to clean the nozzle of the Ultimaker 2+ Connect by applying hot and cold pulls. Hot pulls are used to get the biggest parts of degraded material out of the nozzle and are especially necessary when the nozzle is clogged. With a cold pull, the remaining small particles will be pulled out, ensuring the nozzle is completely clean.

Tip: A cold pull is also recommended when switching to a different material type or when changing the nozzle.

Caution: This procedure requires heating up the nozzle. Be careful and do not touch the nozzle. Protective (thermal) gloves are advised. During this procedure, use pliers to hold the material to prevent injury to your hands in case the material breaks. Ensure the Ultimaker 2+ Connect is disconnected from the Digital Factory or made unavailable for new print jobs.

Preparation

1. Start by removing the material. Navigate to Materials → Unload material and remove the spool

2. Place the print head in the front-right corner

3. Remove the clamp clip from the print head, press down on the tube coupling collet and pull the Bowden tube upwards out of the print head

4. On the display, navigate to Maintenance → Set nozzle temperature

5. Use the controls to set the target temperature to 260 °C for cleaning filament, or 235 °C for PLA

6. Wait for the nozzle to heat up

Hot pull

1. Insert the cleaning filament (or a length of approximately 20 cm of PLA filament) into the print head until you feel some resistance

2. Hold the filament with pliers and gently apply pressure to the material for ±1 second so that it extrudes from the nozzle or until it cannot be pushed any further, and directly pull the filament out with a quick, firm pull
   
   

3. Cut off the tip of the filament that you have just pulled out

4. Repeat this procedure until there is no more degraded material visible on the tip of the cleaning filament.

5. Insert the filament into the print head again and flush some material through the nozzle

Cold pull

1. In the Set nozzle temperature menu, use the controls to lower the nozzle temperature to 135 ºC for cleaning filament, or 90 ºC for PLA

2. Continue to apply some pressure on the material in the print head with pliers

3. When the nozzle has reached the target temperature, use the pliers to pull out the filament with a quick, firm pull

4. Inspect the tip of the filament. If it has a clean, cone-shaped tip like on the left in the image below, the nozzle was successfully cleaned

If the tip of the material is not clean, raise the temperature again and repeat the cold pull steps.

Finish the procedure

1. Lower the nozzle temperature to 0 ºC and wait for the nozzle to cool down

2. Insert the Bowden tube into the print head by pressing down on the tube coupling collet in the print head and pushing the Bowden tube all the way in

3. Pull the Bowden tube and tube coupling collet approximately 2 mm upwards. Keep the tube coupling collet up and push the Bowden tube further in

4. Secure the tube with the clamp clip