Auto-rewinder stand for Rubbermaid 21 cup container

thingiverse

This is a self-standing auto-rewinder stand designed for use with the Prusa MMU2S multi-material unit. I created this rewinder stand to meet the following requirements: * Must fit a spool 90mm wide, which means it must be able to accommodate a spool that is at least 90mm in diameter. * Must have a hub that can hold a 608 bearing, which is the type of bearing used in the MMU2S kit for the spool stands. * Must have an axle with a retaining ring to hold the spring in place. To meet these requirements, I modified the Integrated Auto-Rewind Spool Holder by @VincentGroenhuis at https://www.thingiverse.com/thing:3781815. I changed the spring so that it uses 3 out of 11 blades (for a PETG spring) or 5 out of 9 blades (for a PLA spring), and designed an axle with a retaining ring to hold the spring in place. Here are the instructions for assembling the rewinder stand: **Rewinder Spring:** * The spring blades snap together in an obvious way. The blade with the teeth goes on the bottom of the stack, and the blade with the flat-sided hole goes at the top of the stack. * Place the washer on the end of the axle that doesn't have a built-in spacer. **Axle:** * Slide the retaining ring (washer with a break in it) over the shaft until it snaps into the indentation. * Slide the axle into the spring stack so that the flat-sided hole is against the retaining ring. The axle should stick out the other side. If it doesn't, you have the spring stack on the wrong end of the axle. **Axle+Spring:** * Place the washer on the end of the axle that doesn't have a built-in spacer. * Grasping the ends of the axle with your fingers, drop the ends into the slots on the stand support arms. **Rewinder Hub:** * Push a 608 bearing into the end of the hub shell (cylinder with diamond holes), and into the threaded end cap. You can use the bearings you got with the MMU2S kit for the spool stands. * If the hub of your spool doesn't fit over the end cap petals, you'll need to assemble the hub in the spool. **Hub Assembly:** * Put the appropriate spacer on the hub shell, and insert the shell into the spool so that the arrows on the shell point in the direction of the filament winding. * Place a spacer on the other end of the shell. * Insert the axle+spring into the shell so the teeth of the spring mesh with the teeth inside the bottom of the shell. Screw the end cap on. **Rubbermaid Container Cover:** * Drill a 1/4 inch (or 6mm) hole at the "6 cups" or "1 liter" mark near the bottom of the container (which will be the top of the drybox). * Attach the M6 PTFE fitting to the hole with an M6 nut. **Final Assembly:** * Place the washer on the end of the axle that doesn't have a built-in spacer. * Grasping the ends of the axle with your fingers, drop the ends into the slots on the stand support arms. * Put the stand with the mounted spool on the container lid. * Thread the filament through the M6 fitting. Put a paper clip on it to keep it from retracting. * Place a few packets of dessicant into the stand. * Place the container over the lid stand and press it down. I also fixed a coplanar-surface bug in the OpenSCAD rewinder design, which was causing undesirable artifacts in the STL output. In the OpenSCAD source file, all of my changes are indicated by a comment starting with //am.