S1 Plus Filament Junction Replacement Guide

 Overview

The Filament Junction is the central part of the S1 that manages the transition between spools during operation. It serves two key roles:

• Preload Control – It sets and maintains a set preload force on the filament while the S1 is running, ensuring a smooth and consistent feed into the printer’s extruder.
  
  
• Active Side Detection – It determines which side (left or right spool) is currently active and feeding filament. The filament junction also allows the S1 to determine which side to make active during the power up sequence.

Built-in sensors inside the junction detect when filament has fully exited the S1, which triggers the automatic loading of the next spool after a runout. This enables seamless, uninterrupted reloads with no user input required.

The filament junction and other replacement parts can be purchased separately.

Removing the Filament Junction

1. Remove the S1 Roller sides using this guide.

2. Disconnect Lower Bowden Tubes from the S1 Plus and set them aside

3. Remove the filament junction cover by lightly squeezing the cover and pulling it off of the S1.

4. Remove the three philips screws holding the cover on

5. Carefully lift the case off—it should come off easily.

6. Disconnect the Filament Junction Wire from the PCB.

7. Unscrew the two philips head screws holding on the filament junction and remove it.

Installing the Filament Junction

1. Line up the filament junction so that the two inlets are facing towards the motors on the S1.

2. Install the two philips head screws that hold on the filament junction.

3. Plug in the filament junction wire.

4. Carefully place the cover back on, ensuring that wires fit into designated slots (shown in image below).

5. Secure the three screws back into place to hold on the cover.

6. Snap the filament junction cover back into place

7. Reinstall the Lower tubes of the S1

8. Install the roller sides using this guide.