How to replace a hotend assembly (CORE One)

Relevant for:

CORE One

Last updated 17 days ago

Difficulty

Moderate

Steps

Available languages

Step 1 Introduction

⬢This guide will take you through the Hotend assembly replacement on your Original Prusa CORE One.

The following instructions are compatible with all Prusa Nozzle diameters.

⬢All necessary parts are available in our eshop prusa3d.com.

Note that you have to be logged in to have access to the spare parts section.

Step 2 Tools necessary for this guide

⬢Please prepare tools for this guide:

⬢T10 Torx key

Step 3 Printer Preparation (Part 1)

⬢Close the printer’s door.

⬢Unload the filament. Visit the menu Filament and select Unload filament.

⬢Unload the filament from the printer.

⬢Remove the filament spool from the printer.

Ensure the printer has completely cooled down.

⬢On the printer screen, navigate to Preheat -> COOLDOWN and wait for the temperatures to drop to ambient levels. This may take several minutes.

Step 4 Printer Preparation (Part 2)

⬢Open the menu Control > Move Axis > Move Z and set it to 100mm or more.

⬢Wait until the heatbed moves down.

⬢Turn the printer off using the switch on the back.

⬢Disconnect the printer from power.

Step 5 Top Cover Removal

⬢Open the printer. From the inside, reach for the nylon rivet on the front right of the top cover. Push it out to unlock it.

⬢Then, remove the rivet from the outside.

⬢On the far right side of the cover, remove the other nylon rivet using the same technique.

⬢Remove the top cover.

Step 6 Heatbed Protection

Before proceeding any further, it is recommended to protect the heatbed first!

⬢Use a piece of fabric or other material thick enough to cover the heatbed. This will ensure you won't damage (scratch) the surface during the process.

Step 7 Nextruder Uncovering

⬢Let’s move onto the left side of the Nextruder.

⬢Using the T10 key, remove the two M3x12rT screws holding the side cover.

⬢Remove the cover.

Step 8 Cables Disconnecting

Each connector has a safety latch. It is necessary to press the latch before disconnecting. Otherwise, the connector may get damaged.

⬢Disconnect the hotend heater cable.

⬢Disconnect the hotend thermistor cable.

Step 9 Hotend Assembly Removal

⬢Remove the hotend cables from the cable guide.

⬢

Grasp the hotend with your hand.

⬢Use your other hand to loosen the two thumb screws. There is no need to remove them completely, a few turns are enough.

Watch out, the hotend assembly may fall out!

⬢Slide out the hotend assembly from the heatsink.

Step 10 Hotend Assembly Parts Preparation

⬢For the following steps, please prepare:

⬢Hotend assembly (1x)

The CORE One hotend assembly has a Nextruder Silicone Sock installed by default. It is optional, and you can remove it at any time.

⬢For more information, read the article Nextruder Silicone Sock.

The default nozzle on the CORE One is the 0.4mm HF, (High Flow version) labeled CHT

Step 11 Hotend Insertion

⬢

Locate the corresponding opening on the bottom of the extruder heatsink and fully insert the hotend into the heatsink.

⬢

At the same time, keep the hotend cables pointing to the front, at a slight angle.

The assembly must fit into the recess in the fan shroud with appropriate clearance

⬢Keep pushing the hotend assembly upward and tighten both thumbscrews to secure it in place.

⬢Ensure the hotend is fully inserted into the heatsink. It should align as shown in the picture and must not protrude below the fan shroud.

Step 12 Nozzle Insertion Check

⬢Verify that the nozzle is fully inserted into the heatsink. The copper ring on the nozzle should not be visible if properly seated.

If not fully inserted, it can cause poor heat transfer, potentially leading to nozzle clogs.

To adjust the nozzle position, loosen the thumbscrews, reposition the nozzle, and then retighten the screws, while pushing the hotend assembly up.

Step 13 Hotend Cables Guidance

⬢Locate the cable guide (plastic hook) behind the thumb screws. Guide the thermistor cable through the channel first. Then insert the hotend heater cable.