Prusa Mendel Filament Spool Holder
by ChatterComa, published
This is the best, most practical, and simplest filament manager I've seen or used for a Prusa Mendel. It gets the filament reels out of the way into "unused" space above the printer, allows you to stage two reels for easy switching back and forth, and makes it simple to change reels and to see how much filament is left. When printing, the filament itself is in free air between the reel and the extruder head so there are no jams or problems.
Also great for dual extruder printers.
Holds from 1lb to 5lb standard filament reels.
Note: You can add this Nylock Nut Knob to this thing to allow toolless filament changes.
You can make either a metric (8mm) or imperial (5/16) version. Imperial is easier to source in the US.
- Pair of printed filament spool hubs in the correct size (see below).
- 1 printed frame vertex.
- 20" or 50cm length of threaded rod (5/16 or 8mm).
- 8 flat washers (5/16 or 8mm).
- 6 regular hex nuts (5/16 or 8mm).
- 2 Nylock nuts (5/16 or 8mm). (Nylock nuts have little nylon inserts that hold the nut in place on the shaft unless you force them to turn with a wrench. Any good hardware store should stock them. Most ACE hardware stores stock the 5/16 size.)
Print the filament spool hubs and the frame vertex (which serves as a mount). You can also use the vertex from the Prusa Mendel Lamp Mount, and get the option of adding a gooseneck light.
Download and print the PDF file.
Bend the length of threaded rod as shown in the PDF drawing. Dimensions are not critical (my drawing program shows too much resolution). A bench vise will make this easy, but you can get creative with vise grips or other tools to make the simple bends needed. Be sure not to damage the threads in the areas you'll be putting nuts on. Cut any excess with a hacksaw if needed. You can use these vise pads I made at http://www.thingiverse.com/thing:13948 to hold the rod for bending.
Mount the frame vertex in the spare space on the top 2 rods of your Prusa Mendel. Use washers and regular nuts as needed. Mount the threaded rod in the frame vertex using additional washers and regular nuts. Get everything really tight.
The horizontal portion of the rod should now be above the printer and level with the floor. Make adjustment bends if needed.
Put one Nylock nut on the horizontal part of the threaded rod and crank it on a few inches with a wrench. Put on a flat washer, and one of the hubs. Put your filament spool on (with the filament unreeling towards the center, directly above the extruder), the other hub, another washer, and the final Nylock nut. Tighten the last nut until everything is snug, then loosen it slightly until the reel turns easily but with a very slight drag (so the filament doesn't unspool wildly). This is where you want it.
Feed the filament into your extruder and you're ready to go.
Repeat the above for a second reel mount if you want.
There doesn't seem to be much of a standard for the size of the hole in filament spools. I've encountered four distinct sizes, and made hubs for each of them. I've compiled a list of which filaments use which hub diameter.
- 18.75mm: Taulman's small (1 pound?) filament spools
- 38mm: Ultimachine large (5 pound) spools
- 50mm: Most common size. Used for 1kg spools from Makerbot, Ultimachine, and Protoparadigm.
- 72mm: Unknown. I seem to have thrown away whatever spool I printed this for.
I make no guarantees this list is accurate, as manufacturers seem to commonly change the size they use. In fact, it's probably better to just measure the hole diameter and print the corresponding hub, if you can.