Spool Rack for Prusa MK2/x Multi-Material

thingiverse

The Prusa I3 Multi-material upgrade brings a 4-spool tray with parts and directions to build a very functional and nice tray. However, it is designed to be placed in the space behind the Prusa printer or on a shelf above it. Since I had neither, the Prusa rack was only useful for storing parts like the 16 608 bearings. I took those bearings and some lengths of 20mm V-slot extrusion, a few printed parts, and built a shelf! It's actually a "spool holder rack," but that's just a particular kind of shelf, right? I liked how Prusa used the bearings as surfaces for the spool's rims. I'd been using this type of spool holder for several years, and it works very well. I've seen similar designs on Thingiverse, and I've used this concept for the ones I designed for this rack. I also borrowed and remixed parts from several makers here (listed below). I designed the frame to take up very little table-space since that's how much I had available. The rack's frame wraps tightly around the back and sides of the Prusa frame, positioning the spools directly over the MM extruders' input. With filament feeding off the back of the rack, it has an almost direct arc to the extruder while leaving plenty of room for extra filament retracted during color changes. I put slot guides on the bottoms of the spool/bearing holders and left them unconnected to their matching bearing holder so any spool width can be quickly accommodated. The spools are very stable in use and can be re-positioned easily when desired. I used my spool rack for several weeks without any filament guides, and it worked fine – although it looked a little messy. However, I couldn't leave it at that, so I designed a fairly whimsical filament guide – and did it in multiple colors just for fun! I've included both single and multi-color versions; they look a little peculiar but work very well and can be easily positioned for each spool. When I finished the rack, I was reminded of a filling station pump area – especially with spools on top. So, I came up with a little multi-color sign to add to that image. The name "Catnap Motors" (slogan "The Purrfect Ride" – [a division of "Catnap Industries"]) is the name of a pseudo-company I created many years ago. This sign is totally optional, and you can always make something yourself and glue a bit of slot-cover to the back to clip it in place. I've included a cut list for the extrusions, a parts list for the hardware, and a parts list for the printed parts. I've also made a stab at assembly instructions (see the Thing Files for the .rtf file). Only two of the extrusion pieces must be cut precisely; for the others, a millimeter or two either way won't ruin anything. Note that the pieces are dimensioned to fit the printer and to be cut from two 1500mm V-slot extrusions. I may have over-engineered the joints – the corner brackets are easy to print and can be decorative as well as functional. So, I've put one or two at every axis change. The "Suggested" links in the parts list are just that; you can use them if they work for you, thank the makers, or blame me if they don't! I gratefully acknowledge these makers for their designs that I've remixed or borrowed for this project: * V-slot corner bracket and T-bracket from spauda01's D-Bot project: https://www.thingiverse.com/thing:1001065 * V-slot covers resized from sheffdog's near-perfect profile: https://www.thingiverse.com/thing:832077 * Bolts and nuts generated using mike_mattala's excellent Nut Job library: https://www.thingiverse.com/thing:193647 * Raspberry Pi case (totally optional to this build) from hofftari's Pi case for Prusa: http://www.thingiverse.com/thing:1325370 You'll also see in the photos a Raspberry Pi case (totally optional to this build). This is hofftari's Pi case for Prusa, which I use with all of my raspis. I used Simonarri's Miter Razor to clean up the ends of the slot cover strips: https://www.thingiverse.com/thing:912051 – it's not really intended for cutting plastic but does!