Left Side Panel Filament Mod for Core One

The Core One panels are not symmetrical and can't be easily swapped to place the spool on the left side. This solution involves replacing the left acrylic panel to enable the use of filament spools on the left.

Preparations

The side filament sensor and the right handle share the same screws, with the nuts integrated into the sensor. You will need some additional hardware:

• 2x M3 nuts (for reattaching the handle)
• 2x M3 machine screws, length between 8 and 15 mm (for attaching the side filament sensor to the panel)

Tools and other:

• set of allen and star keys from Core One accessories
• pliers for cutting zip ties
• zip ties
• some trays for rivets and hardware (like these)
• a tool for easier removal of rivets (like this)

A bag of gummy bears might come in handy during assembly (just order another printer kit to get some gummy bears from Prusa).

Printing info

Printing may be tricky — the panel is 363 mm long and just barely fits within the Core One’s build volume when placed diagonally. It is designed to be printed this way and does not require supports for its features (there is just one bridge, which prints fine without support).

The model includes a built-in brim-like base, as there isn't enough space for a standard brim generated by the slicer. Integrated small side supports are present on the base, along with some protrusions for attaching tree supports, which prevent the panel from wobbling during printing. These protrusions are necessary because tree supports don't adhere to the panel at this angle, even with zero contact distance. The base and supports can be easily removed after printing, with some cleanup using a knife and possibly sandpaper.

When printing the prototype in PLA, it worked fine even without the attached tree supports. With PETG I experienced issues with layer shifts. To address this, I added protrusions for attaching tree supports and adjusted some print settings to prevent the nozzle from bumping into the model and causing layer shifts. (These adjustments may not be necessary—perhaps the attached supports alone are sufficient.)

Printing instructions

Use a material that can withstand heated chamber temperatures up to 60 °C. High-temperature PLA (PLA HT110) or PETG should be ok. The panel is cooled from the outside.

Use the attached 3MF project with the recommended settings.

If you prefer to set it up yourself, here’s how I printed the final version in PETG.

Add “panel.stl” and use the Place on Face function. Select the small face in the center.
Use Place on Face again and select the bottom face. Then click on Arrange.
Right-click on the panel model and choose Add Support Enforcer → Load…, then load “support enforcer.stl”.

Layers and perimeters:

• 0.4 mm nozzle
• 0.20 mm STRUCTURAL print profile
• Perimeters: 3
• enable Avoid crossing perimeters
• Seam position: Nearest

Infill:

• 15% Gyroid infill

Supports:

• enable Generate support material
• disable Auto generated supports
• Style: Organic
• Top contact Z distance: 0 (soluble)
• Top interface layers: 0 (off)

Speed:

• Max print speed: 100 mm/s

Filament - FIlament overrides:

• disable Use ramping lift
• enable Lift height: 0.25 mm

Printing at the edge of the bed may cause adhesion issues. To avoid any surprises, you can add a pause in the print after a few millimeters and secure the base with some magnets.

For Prusament PETG I also set extrusion multiplier to 0.986, as recommended on the forum.

Post print cleanup

Cut off the base and support protrusions (marked in red on the model image). It doesn't have to be perfect, as the cuts will be facing the metal frame.

Assembly instructions

This modification should be simple and easy, even if you have a factory-assembled Core One. Whenever you feel uncertain about the Core One internals, check the kit assembly guide.

After each step, reward yourself with a gummy bear, if you’ve got some.

Remove the top and left panels by pushing on the rivets from inside the printer. They will pop out and can be easily removed using a rivet tool (or your fingers, if you prefer). Keep the rivets, as they can be reused multiple times.
Unscrew and remove the right panel handle using a star key. Remove the short PTFE tube from the handle while pressing on the collet. Remove the collet from the handle.
Unscrew the two screws at the back of the chamber and remove the rear cover.
Remove the cover from the side filament sensor by unscrewing the screws on the sides (leave the middle one in place).
Unscrew the small screw holding the sensor circuit board, then remove the circuit board and disconnect the sensor cable. While pressing on the collet, remove the PTFE tube from the sensor. It may require some force, as the tube is very slippery and difficult to grip.
Cut and remove the zip tie securing the sensor cable on the XY gantry.
Cut the zip ties securing the cables at the back. Carefully pull the sensor cable out through the left hole (when looking from the back) and push it into the right hole, where the motor cables are already routed. Inside the chamber, use tweezers or a similar tool to pull the cable up behind the left motor. Secure the cables at the back with new zip ties.
Remove the two cable ties from the cable and PTFE tube coming from the print head. Keep the cable ties on the swingarm. Pull the PTFE tube out from the cable ties on the swingarm. Then, use one of the previously removed cable ties to attach the PTFE tube to the end of the swingarm, wrapping it around the existing cable tie.
Push the collet from the handle into the panel. Use tweezers or a similar tool. It can be a bit tricky. It may seem like it won't fit, but once you find the right angle, it slides in with minimal force.
Attach the new panel using the three nylon rivets at the top only. Do not attach the side rivets yet. Push the PTFE tube through the guide hole and out of the panel. Push the sensor cable through the panel as well, but do not secure it under the clips yet.
Push the sensor on the PTFE tube. It may need some force. Attach the sensor circuit to the cable and assemble the side filament sensor as it was before. Attach the cover plate of the side filament sensor.
Attach the side filament sensor to the panel using two M3 screws (8–15 mm should work). The screws are at a tricky angle, so allen head screws and an allen key with a ball end may be the best option here. Push the short PTFE tube from the handle all the way in.
Secure the sensor cable under the clips on the panel.
Secure the panel with the remaining two rivets on the sides. Attach the right panel handle using two M3 nuts in place of the side filament sensor. Attach the rear cover. Attach the top acrylic panel by simply placing it on top. The rivets aren’t necessary, unless you’re in a space station.

Check that the side filament sensor is working, then enjoy your modified printer!