Cleaning the nozzle of your Ultimaker 2+ Connect can improve your printing results. When dirt or carbonized material accumulates inside the nozzle, you may have extrusion problems, or these burnt parts can show in your printed model.

There is a simple process for cleaning the inside of the nozzle that does not require disassembly of the print head. You will only need to remove the Bowden tube. This is called the hot and cold pull method. You can use cleaning filament or PLA for this.

The cleaning process is split into two steps: 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 Hot pull Cold pull Reassembly

1. Unload material	Remove the material from the printer. In the Materials menu, select Unload. Wait for the nozzle to heat up, open the feeder, and pull back the filament.
2. Place print head	Manually place the print head in the front-right corner of the printer. This gives you easy access to the print head and prevents damage to the print head shafts.
3. Remove Bowden tube	Remove the clamp clip from the print head. Push down on the white tube coupling collet and pull the Bowden tube up and out of the print head.
4. Prepare cleaning filament	Take one piece of Ultimaker cleaning filament. If you do not have this available, cut off a length of filament, approximately 20 cm. You can use PLA for this, but other (non-flexible) materials will also work.
5. Heat up nozzle	In the Maintenance menu, select Set nozzle temperature. When using cleaning filament, increase the temperature to 260 ºC. For PLA, choose 235 ºC. Wait for the nozzle to heat up.

1. Insert filament	When the nozzle has reached its target temperature, insert the piece of filament into the print head. It is recommended to hold the filament with pliers.
2. Apply pressure	Apply some pressure to the filament for ±1 second so that it extrudes from the nozzle or until it cannot be pushed any further.
3. Hot pull	After applying pressure, directly pull the filament out with a quick, firm pull. This removes the majority of carbonized material.
4. Cut and repeat	Cut off the tip of the filament that you have just pulled out. Repeat these steps several times until the tip comes out fairly clean.

Above. Hot pull results. Repeat the steps until the filament comes out clean. Left. Apply pressure to the filament using pliers.

1. Insert filament	After the last hot pull, put the filament back into the print head and apply pressure with pliers.
2. Lower nozzle temperature	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.
3. Apply pressure	Continue to apply pressure as the nozzle is cooling down. This prevents air bubbles forming and gives the best results.
4. Cold pull	When the nozzle has reached the target temperature, use the pliers to pull out the filament with a quick, firm pull.
5. Cut and repeat	Inspect the tip of the filament. If there is still carbonized material visible, cut off the tip, raise the nozzle temperature, and repeat the cold pull. When the filament has a clean, cone-shaped tip like on the left in the image below, the nozzle was successfully cleaned.

1. Exit menu	Press the X icon in the corner of the display to exit the Set nozzle temperature menu. You can select Skip cooldown if you want to reload your material afterward.
2. Insert Bowden tube	Push the Bowden tube back into the print head. Make sure it is fully inserted. Secure it with the clamp clip.
3. Load material	In the Materials menu, select Load material. Follow the steps on the display to reload your filament. More information on loading filament can be found on this page.
4. Check extrusion	If the hot and cold pulls were performed correctly, filament should be flowing smoothly from the nozzle again.

Finished!

The nozzle is now clean again on the inside for optimal extrusion. If you have any questions about this process, or when you continue to experience extrusion problems with your Ultimaker 2+ Connect, contact support by submitting a ticket.