By default, changing the nozzle of the machine does not have to be done very often. The nozzle should be changed only when it is fully of partially clogged, dirty, or when a different size of nozzle is required.
The nozzle is the part located at the end of the extrusion system that determines the shape of the filament. There are several reasons for changing the nozzle.
- When a partial or full obstruction occurs in the nozzle, pressure builds up in the extruder. When the pressure becomes too high, the nozzle can be pushed out of the machine.
- When the nozzle is dirty (encrusted with hardened plastic), the outcoming filament can be scratched or damaged.
- Several sizes of nozzles exist: 2mm, 3mm, 4mm. The "mm" refers to the diameter of the opening. The 4mm nozzle is the one most commonly used, however with different materials, a smaller nozzle can give better extrusion results.
Generally speaking, the nozzle becomes clogged or pushed out when the material becomes too solid before exiting the machine. This can be due to excessive cooling, incorrectly positioned fans (blowing straight on the nozzle), insufficient temperatures (especially in Heater 1 (H1)), excessive screw speed, filler segregation (typically when processing fibers-filled plastics as well as other composites). In these cases, it may become important to change the nozzle and also fix the issue that caused the problem in the first place. This document will explain step by step how to replace the nozzle.
Collect the following items
- Hex (also known as Allen) key 2.5 for M4
- Wrench 13
- Wrench 19
- Flat nose pliers
- Power cable
- Heat-resistant gloves
- Cuts- and abrasiveness- resistant gloves
- Nozzle package: nozzle, ferrule, fitting nut
- Metal tie wraps (not always mandatory)
It is highly recommended to perform these operations when the machine is filled with: PLA, HDPE, or Devoclean MidTemp.
Step 1: Preparing the machine
To remove the top hood follow these instructions and then continue on this page.
Cover the filament sensor with a sheet of paper or cardboard, and point the filament fans out forward.
Step 2: Remove nozzle plate
Carefully remove the nozzle plate with the Hex key OR pull it carefully off if it is attached with magnets. This will depend on your machine model.
Step 3: Open insulation wool
Cut the front tie wrap with a cutter, and open the insulation wool so that the nut of the nozzle is visible.
Depending on the shape on your tools, the way the wrap is positioned, and the way you perform the subsequent operations, you might be able to leave the tie wrap intact, and work without cutting it. However, you will still have to carefully open the insulation wool towards the sides and close it back at the end.
Step 4: Setting the temperature
Plug in the power cable and turn on the machine.
Go to "Settings" and set the temperature of "Heater 1" (indicated with the red arrows) above the melting point of the material that is currently in the extrusion system.
It is also possible to remove the nozzle during an extrusion experiment, when the machine is already hot. In order to do so, you can either:
- Set the screw speed on 2RPM, without stopping the flow of plastic.
Quickly open the insulation wool, remove the nozzle, and increase the speed again.
Note: You would want to do this if the machine is becoming clogged but you do not want to let the plastic sit and solidify inside the barrel; releasing the pressure at the front of the machine might allow for an unclogging of the machine before it is too late.
As a safety precaution be careful to avoid the flow of molten plastic.
To mount a new nozzle you will have to stop the flow.
- Stop the flow, remove the nozzle before the temperature drops.
If you stop the flow (stop extrusion) at any point, make sure that the material inside the barrel at that point is PLA, HDPE, or Devoclean MidTemp EZ. If not, you should keep extruding (with or without the nozzle) until the whole barrel is filled with PLA, HDPE, or Devoclean MidTemp.
Press "Start extrusion" and select "Manually".
Step 5: Remove the nut
When heater 1 is at the desired temperature, the nut can be removed. Use wrench 13 to support the elbow fitting and use wrench 19 to loosen the nut.
The fitting is hot!
If the nut is loose, carefully grip the nozzle with the pointed nose pliers and pull it down. Sometimes rotating the nozzle inside the knee, or pulling it towards different directions can help get it loose.
Step 6: Clean the elbow fitting
Make sure the inside of the elbow fitting is as clean as possible. Try to remove all the plastic. You can do this carefully with, for example, tweezers. It is of the utmost importance to have the edge (indicated with red in the diagram below) thoroughly cleaned.
Once residue hardens inside the knee, you might not be able to fit a new nozzle in.
Turn off the machine.
Remove all excess plastic from the nut (if you keep using the old nut). This step is often difficult but sometimes the nut will be detached almost fully clean. It is recommended to use a new nut every time the nozzle is changed.
Step 7: Mount the new nozzle
When the elbow fitting is clean, you can push the nozzle inside the elbow fitting. The nozzle should be pressed as far as possible into the elbow fitting, so that the colored edges (indicated by the color red and blue) touch each other. If it is too hard to push the new nozzle in, this might mean that the inside of the knee is not clean enough.
The nozzle is correctly placed in the elbow fitting if it looks like the diagram below:
Now that the nozzle is in the right place, the nut that holds these parts must be attached. Tighten the nut on elbow fitting as tight as possible without causing damage. Beware! It is possible that the nozzle has dropped down. It is extremely important that the nozzle is pressed tightly against the elbow fitting before the nut is tightened tightly. It is recommended to push up the nozzle and the nut with one hand (equipped with a heat-resistant glove), while starting tp tighten the nut with the other hand.
The nozzle is mounted correctly if it looks like the two diagrams below.
Step 8: Place insulation wool back
Fold insulation wool back around the extruder and use new tie wraps to hold the isolation wool on its place. If you had not cut the tie wraps in the first place, just make sure you close the insulation wool back around the head of the barrel and make sure the tie wrap is still tight.
Step 9: Re-attach nozzle plate
Reverse of step 2. Attach the nozzle plate with the Hex key OR with magnets, depending on your machine model.
Step 10: Mount top hood
Follow these steps in reverse order to mount the top hood back on the machine.