Filament Maker maintenance: replacing the nozzle

Changing the nozzle of the machine does not have to be done very often by default. The nozzle should be changed 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 a 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. That refers to the diameter of the opening. In few, specific cases, a nozzle smaller than 4mm 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, mispositioned fans (blowing straight on the nozzle), insufficient temperatures (especially H1), excessive screw speed, filler segregation (typically when processing fibers-filled plastics as well as other composites). In other terms, in those cases, it is important to change the nozzle and also fix the issue that caused the problem.

This document will explain step by step how to replace the nozzle.

Collect the following items:

  • Hex key 2.5 for M4
  • Wrench 13
  • Wrench 19
  • Flat nose pliers
  • Nipper
  • Power cable
  • Heat-resistant gloves
  • Cuts- and abrasiveness- resistant gloves
  • Nozzle package: nozzle, ferrule, fitting nut
  • Metal tie wraps (not always mandatory)

Foreword

As explained later, it is highly recommended to perform these operations when the machine is filled with: PLA, HDPE, or Devoclean MidTemp.

Opening the machine

Step 1: Follow the instructions from step 1 up to step 4 to remove the top hood and then continue at the next step on this page.

Step 2: Cover the filament sensor with a sheet of paper or cardboard, and point out the filament fans forward.

Remove nozzle plate

Step 3: Carefully remove the nozzle plate with an Allen key OR pull it carefully off if it is attached with magnets.

Open insulation wool

Step 4: 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.

Setting the temperature

Step 5: Plug in power cable and turn on machine.

Step 6: Go to settings -> 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.

IMPORTANT: 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:

  • not stop the flow of plastic, set the screw speed on 2RPM, quickly open the insulation wool, remove the nozzle, and increase the speed again. 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. When doing this, be careful about the flow of molten plastic. To mount a new nozzle however, you will have to stop the flow.
  • stop the flow, remove the nozzle before the temperature drops.

IMPORTANT: 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. If not, you should keep extruding (with or without the nozzle) until the whole barrel is filled with PLA, HDPE, or Devoclean MidTemp.

Step 7: When press ‘Start extrusion’ choose ‘Manually’ for the question ‘When heating is done’.

Removed the nut

Step 8: When heater 1 is at the desired temperature, the nut can be removed. Use spanner 13 to support the elbow fitting and use spanner 19 to loosen the nut. Caution: the fitting is hot! If the nut is loose, carefully grip the nozzle with a 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.

Clean the elbow fitting

Step 9: Make sure the inside off the elbow fitting is as clean as posible. 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) thoroughly cleaned.

Mounting a new nozzle inside a dirty knee will probably result in said new nozzle popping out after a few minutes of use.

Step 10: Turn off the machine

Step 11: 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.

Place the (new) nozzle

Step 12: 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) the surfaces 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.

Step 13: The nozzle is correctly placed in the elbow fitting if it looks like this picture (indicated with the color red and blue against each other)

Step 14: Now slide the ferrule ring around the nozzle, tight against the elbow fitting.

Step 15: The ferrule ring is placed correctly, if it looks like the one below.

Step 16: Now that the nozzle and ferrule ring are 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, the compression ring, and the nut with one hand (equipped with a heat-resistant glove), while starting the tighten the nut with the other hand.

Step 17: The nozzle is mounted correctly if it looks like the two images below.

Place insulation wool back

Step 18: 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.

Mount upper plate

Step 19: Follow these steps in reversed order to mount the upper plate back on the machine.