MMU Under Shelf Auto Rewind Spool Holders

thingiverse

*** Update *** Added new v3 Spool and Spring, check out the details here https://www.thingiverse.com/thing:3248031 I also added Black bumper/spacers called "Spool Holder Bracket Spacer Guide.stl", which can be clipped onto side brackets to prevent spools from getting too close to the edge. Inspired by Vincent Groenhuis's Auto Rewind Spool, I decided to create under-shelf/hanging Spool Holders for these. This design uses metal rods and 608 bearings from Prusa MMU spool holders. I added a square end stop to the spring design from Vincent Groenhuis and made some Hangers for them. The Hangers print flat, making it easy to print them in PLA. You'll need 1x Base and 2x Side Brackets for each set. The side brackets press firmly into the base, allowing you to screw them up as one piece. To make things easier for myself, I made the base units slot together with tabs. Once you have your first holder in place, the others just push up and slot into the existing one, then screw that one in place too. Less measuring! For the Auto Rewind spool, you'll need: 1x Wide Hub (https://www.thingiverse.com/download:5570849) from Vincent Groenhuis's original design. 1x Spring Remake (https://www.thingiverse.com/thing:3248031) from my remake of the spring, which includes a square end stop. Print the Spring at least in PETG; I found PLA lost some of its springiness over time (PETG still works great). I also printed the Wide Hub in PETG so they'd be the same once glued together. To assemble the Spool: Push one metal rod into the square end stop through the spring - it's a tight fit, so make sure you push it all the way to the end. Push a 608 bearing into each side of the Wide Hub. Glue the Spring to the Wide Hub, making sure to only glue around the edge of the Hub. This allows the rest of the spring to move freely. As the spring is already on the metal rod, you can slide this rod through both bearings in the Hub and use it to help center the spring while gluing. Once together, push on the round Spool End Cap to keep everything secure - it's a snug fit, so make sure it's all the way on. The final length of the whole shaft should be 22-23mm long. I've included pictures to help you understand the process better. I also made a through-the-shelf PTFE tube holder/feeder that takes M10 PTFE tube connectors - check out M10 Feeder Mount in the files section. You'll need to purchase an M10 connector for each one. Most of my Filament Spools work fine with this setup and stay centered, but I did find some spools would wander slowly to the side of the spool. So, I made a clip-on guide "Spool Holder Bracket Spacer Guide" in the files section - it pushes onto the Side Brackets (see photos) and stops a Spool reel from wandering too far to the edge. I found the Prusa Spool holders to be very fiddly to use, feeding filament through holes and elbows then only having a few inches to feed filament all the way to the MMU. With my new setup, changing spools is quick with plenty of space to feed/push filament down the tubes. I hope you find this useful - please post a make to Thingiverse if you do make one. FYI: The Green Spool Holder in the pictures was printed in PLA and shows some spring loss over time. The Black ones are PETG