Prusa MMU3 Low-Friction Drybox Filament Buffer

Overview

For a video tour of this tower setup, please visit this reddit post. In this video I explain how this quick-release system works along with some of the other upgrades that I have made for my Prusa i3MK3S+ with MMU3! (:

This new filament buffer design is intended to create an easy way for a filament drybox to connect to an MMU from underneath the 3D printer in a tower setup.

File Organization

• Inside this post you will find GCODE, 3MF, STL, STEP, 3DM, and image files. 
  • The GCODE files are available as nested assemblies for easy and efficient printing. 
    • Each file contains the parts needed to complete 1 buffer out of the 5 needed for a complete assembly.
    • The files are organized by what color one is recommended to use for the parts. Please refer to the images for reference.
  • The 3MF files are available as individual parts as well as nested assemblies for the print bed.
  • The STL files are available as individual parts.
  • The STEP and 3DM Files contain all of the parts. This project was designed in Rhino3D, so the 3DM files contain the most information about layers, colors, and they come annotated with text. The STEP files contain the 3D models and only some 2D curves.
  • The image files, which are provided in the same zip folder as the STEP and 3DM files, provide an overview of the parts and their quantities as well as their assembly.

The Drybox Portion

• The drybox enclosure is made from an Ezy Storage 50L Tote that I grabbed from my local Home Depot. Here's the purchase link to it.
• There's a great rechargeable dessicant module that I like to use for my drybox as well. Here's the purchase link to it.

The Filament Buffer Portion

• The overall filament buffer assembly is made from 5 standalone assemblies that attach to the back of the drybox in-line with the center of the spools. Each of these standalone assemblies is made from 11 different kinds of parts that have been outlined in the files below. 
• A great deal of care has been taken into the aesthetic of the top finishes as well as the finish and tolerance of the interfaces between parts. This is why you'll see a large amount of ironing and infill modifiers for the STL files. However, to keep things as intuitive as possible, I have firstly provided 3MF files for all of the parts so you don't have to worry about putting those files together unless you want to do so.
• The face plates of the filament buffer come in three different designs: feathers, fungi, and honeycomb. Feel free to mix and match all you like! Using the STEP files provided, you can also create you're own if you'd like.

The 3D Printer Tower

• These files are available in another post of mine on Printables. Here is the link!

The Drybox Spool Holder Rail

• These files are available in another post of mine on Printables. Here is the link!

The Ikea Lack Table Passthrough Couplers

• These files are available in another post of mine on Printables. Here is the link!

Assembly

• All of the parts have been categorized into numbered folders for your convenience. The “0. Component Sets” folder contains nested assemblies for an easy and efficient printing experience!
• Assembly requires the use of some 3rd party hardware in addition to 3D printed parts.
  • 3mm cap-head screws and hex nuts like the ones that the Prusa is assembled with.
    • M3 Screw: 14mm (3 qty per buffer, 15 in total)
    • M3 Screw: 20mm (4 qty per buffer, 20 in total)
    • M3 Nut: Hex (7 qty per buffer, 35 in total)
    • Here's the purchase link I used. (Qty: 1 variety pack)
  • "PC4-M10" PTFE couplers. 
    • Here's the purchase link I used. (Qty: 10x couplers at minimum)
  • PTFE Tubing. For high performance results, I'd recommend using Capricorn tubing.
    • About 1m for each buffer, cut to size depending on your specific setup.
    • Here's the purchase link I used. (Qty: 2 packs of 3m)
  • For the Drybox, I'd recommend attaching the feet with some kind of adhesive like glue or a 3M command strip. This will reduce the amount of penetrations in the enclosure and the amount of moisture that can sneak into it.
  • You'll also have to drill through the drybox to create holes for the filament to pass through into the buffer. When you drill through plastic, make sure to take it slow and work your way up to the final diameter of the hole with multiple bits to avoid cracking the plastic.

Use Instructions

• Make sure to place the drybox in an orientation that is accessible for you. 
  • Since the buffers are accessible from behind the drybox, it's nice to have some space to walk behind the printer to access them for ease of maintenance and proper feeding of the filaments to the MMU. For me, I was able to still place it against a wall, but it was just uncomfortable to reach with my hands at times.
• In order to use the drybox, simply follow these steps.
  1. Line up the filament spools on the spool holder rail
  2. Feed the filament through the buffer. In order to get it to pass through that rounded 90 degree bend by the wheel, place your fingers through the opening of the face plates and guide the filament with them.
  3.  When all of the filament spools have been loaded into the buffer, place your rechargeable dessicant module inside.
  4. Close the lid, and you're ready to go!

Disclaimer

• While the drybox is intended to keep filament protected from moisture, the filament inside of the buffer portion is exposed to the air. Thus, if your filament is left out for more than a few days, it might become brittle and snap. If it does, you can simply remove the lower frame of the buffer to remove any fragments of broken filament. For reference to what this kind of breakage looks like, please refer to the closeup photo of the buffers. You'll see a pink strand of filament that has snapped for this reason.
• It will take almost 200 hours of printing to create all of the parts for this assembly. It takes persistence, but if you're down, it's a fun project!