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Changing or replacing the nozzle (MK2.5S/MK3S/MK3S+)

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Last updated 3 months ago
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The Original Prusa i3 printers use the E3D V6 Hotend. They are compatible with E3D V6 1.75 mm nozzles. The stock nozzle that accompanies the printer is an E3D 0.4 mm brass nozzle, but other types and diameters can be used as well. The following procedure applies to all nozzles, except the Olsson Ruby.

To replace the Olsson Ruby nozzle, follow the instructions on the official 3DVERKSTAN website. Otherwise, you could damage it!

Tools necessary

  • 2.5 mm Allen key (Included with assembled printers and kits)
  • 7 mm spanner/socket or pliers (7 mm spanner/socket not included with assembled printers and kits)
  • 17 mm spanner (not included with assembled printers and kits)
  • Small plate or aluminium foil (not included with assembled printers and kits)

Procedure

Follow this procedure exactly! Omitting steps can cause leaking and extrusion issues outlined at the end of this article.
  1. Gain better access to the nozzle by moving the extruder (Z-axis) as high as possible: Go to LCD Menu - Settings - Move Axis - Move Z. Spin the Knob to adjust the height.
  2. Unscrew the two screws on the print fan and the single screw securing the fan shroud. Remove both parts (picture below).

extruder

  1. Preheat the nozzle to 280 °C from LCD Menu - Settings - Temperature - Nozzle. Heating the nozzle is essential for this process.
CAUTION: Heated parts can cause severe burns!
  1. Unload the filament from the LCD Menu - Unload filament. Optionally, perform a Cold pull (MK3S/MK2.5S).
  2. Hold the heater block with a 17 mm spanner (M10) or adjustable wrench.
Be extra careful around the fragile hotend heater and thermistor wires. You can break them off or short circuit the heater with your spanner!
  1. Unscrew the nozzle using the supplied pliers. If you are using the E3D nozzles from our online store, use a 7mm spanner (M4) or 7 mm socket. Be careful, the nozzle is still hot! Place it out of the way on your non-flammable surface.
  2. Make sure that the set temperature (280 °C) didn't change. Holding the heater block with your spanner, carefully screw the new nozzle in and tighten it gently, but firmly. Do not use excessive force!
Our service- and assembly team use a torque wrench rated for 1 - 5 N m, and tighten the nozzle with a force of 2.5 N m (Newton Meter).

Final inspection

There must always be a gap (~0.5 mm) between the nozzle and the heater block (left picture). The nozzle must be tightened/secured in the heater block, locked against the heat break, while heated (right picture). Failing to do so will cause leaks (center picture).

It is necessary to redo the First Layer Calibration (i3) after replacing the nozzle. If you installed a nozzle with a diameter other than 0.4 mm (0.25, 0.6, 0.8 mm), please see Different nozzle types.
You can find this procedure as a video on our YouTube channel. Be aware that some steps may differ slightly from the procedure outlined here, and printed parts of the extruder may look a little different than yours.

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