3.6. Swapping nozzles on the Prusa i3 Mk3


These notes are based on my experiences with the Prusa i3 Mk3 and Artillery/Evnovo Sidewinder X1 printers. If you are using a different printer, please verify the hardware details are similar.

Changing the nozzle on your Mk3 is a straightforward procedure, and only takes a few minutes. These notes highlight a few tips and tricks to avoid common mistakes during this procedure.

3.6.2. Preparing for the nozzle swap

It’s a good idea to prepare things for doing the nozzle swap to avoid repeating steps.

  1. Do a cold pull to clear the currently-mounted nozzle before removing. This will keep the stored nozzle clean and ready to print, and will avoid potential problems with higher-temp material accumulating in the nozzle interfering with later prints at lower temps.

  2. Raise Z to max. Press and hold the front knob until it chirps, then rotate it to lift the Z axis. Push the knob again when done.

  3. Heat hotend to a high temp (e.g. 280C) well above normal print temps. The goal is to heat the hotend and nozzle for maximum expansion so things will fit tightly as they cool.

  4. As you wait for things to heat up, clean the hotend using a soft brass brush. Give the hotend and nozzle a light scrubbing, being careful to avoid the thermistor and heater cartridge wires that protrude from the left side as viewed from the front of the printer. You want to remove any built-up filament and other gunk that has built up before it starts dropping into your prints.

  5. Give the nozzle a cleaning as well. If you are using a coated nozzle, replace the brass brush with a small width of cardboard to avoid removing the coating. Be sure to clear any build-up obscuring the nozzle size markings.

3.6.3. Old nozzle removal


As you remove the mounted nozzle, be sure to brace the heater block to avoid twisting the heat break.

  1. Use a 16mm spanner or block holder to brace the heater block.

  2. Use a 7mm socket wrench to loosen the mounted nozzle. Rotate from right to left as viewed from the front (counter-clockwise if viewed from below). Loosen until the nozzle comes loose in the socket.

  3. Set aside the hot nozzle. Use pliers to remove it and set it on a surface to cool. The nozzle is extremely hot, so be sure to place it in a safe space.


Steel nozzles are magnetic and can pop up into odd places on the printer underside. If you drop one, be sure to check the magnets under the print bed.

3.6.4. New nozzle prep

Spend a minute preparing the new nozzle to avoid headaches later on.

  1. Check to make sure the nozzle is the appropriate size and type. Nozzle markings are small and easily obscured. Last chance!

  2. Buff the nozzle tip on a leather strop or jeans. This helps by providing a shiny surface that is less prone to attracting and snagging filament during the print.

3.6.5. New nozzle installation


As you mount the new nozzle, be sure to brace the heater block avoid twisting the heat break.

  1. Use a 16mm spanner to brace the heater block.

  2. Insert the new nozzle into the 7mm socket with the threads protruding.

  3. Insert the new nozzle into the heater block. Rotate from left to right as viewed from the front. Tighten until the nozzle fits snugly. Do not over-tighten! Two fingers should be sufficient to tighten the nozzle. Make sure it is snug so filament can’t ooze out over the top.

This is a good time to store the old nozzle before it wanders off.

3.6.6. Live-Z recalibration

You should re-do Live-Z calibration after every nozzle swap.

At this point, you should be able to resume printing. Remember that you need to re-slice any models to use different nozzle sizes.

Contact and feedback

You can find me on the Prusa support forums or Reddit where I lurk in many of the 3D printing-related subreddits. I occasionally drop into the Official Prusa 3D discord server where I can be reached as bobstro (bobstro#9830). You can email me directly at projects@ttlexceeded.com.

Last modified Apr 2, 2021. Last build on Apr 22, 2022.