This retrofit converts a Snapmaker J1 from rear-mounted filament to a front-loading spool system. The two filament holders utilize the empty space inside the printer to the left and right of the bed and can be loaded from the front which can be more convenient.

It is comprised of two adjustable width spool holders that feed the filament downward into a new PTFE tube that pass under the base and up through ports that replace the rear-mounted plastic hangars and through the existing mechanism to the extruders (see photos).

Spool holders mount to existing screws on the J1 by changing out the existing M3 screws for longer M3 x 16mm screws (see photos).

This latest version adds an extra 6 mm of clearance between the top of the spool and the bottom of the foam on which the extruder rests when it is parked (see photo with rulers to see the difference). This is especially useful for those using 8" diameters spools. Spool Base 3B adjusts the size of the skateboard bearing mounting posts on the base piece to accommodate variations in different materials.

This design has been beta tested on multiple slicers (Luban, Cura and Prusa) with PLA and PETG materials by members of the facebook Snapmaker J1 Owners group (https://www.facebook.com/groups/snapmakerj1). My thanks to all who assisted in this project.

(1) The base piece has been updated(spoolbaseV2.stl) to ensure the roll does not pivot into the direction of the printing table during high acceleration start/stops. It hasn't happened to me, but others have mentioned a fear of this - so I've changed the base to address this, to be extra safe.

(2) The bearing mounting pegs on the sliding piece (SpoolSlider4.stl) have been lowered by 2mm to better align with the new base piece. Thanks to maker "dreidfuchs" for catching that for us.

**(3) I've removed the older version of the spool base file as the new one has proven to be much better and eliminates any potential issues as mentioned in comment (1) above.