Spool Holder for Rubbermaid Dry Box (625-2RS Bearings)

The Rubbermaid 21 cup container makes a convenient dry box for humidity-sensitive filaments.  My design needs a single hole in the container for the bowden tube passthrough, and uses rubber washers to preserve the airtight seal.  There is room under the base for desiccant and silica gel packs.  This design will fit a maximum diameter of 210 mm, maximum width of 80 mm, and a minimum diameter of 165 mm.  Yes, it fits Prusament spools!

Supplies

For the spool holder you will need:

• (4) 625-2RS bearings for the rollers
• (4) M5x10 BHCS for the bearing axles
• (4) M3x5x4 heat set inserts for the base
• (4) M3x8 BHCS to attach the sides to the base

For the bowden tube passthrough you will need:

• (2) 0.75 inch (19 mm) garden hose washers; or custom size washers (discussed below)
• Drill and 1/2 inch (12 mm) or 3/8 inch (9 mm) drill bit

For the optional hygrometer (link at bottom) you will need:

• (2) M3x8 screws
• (2) M3x5x4 heat set inserts for the base

I used washers for a garden hose to seal the bowden tube passthrough.  The size should be universal, though I modeled the stl files around these from my local store: https://www.acehardware.com/departments/lawn-and-garden/watering-and-irrigation/garden-hose-connectors/7229438.  Or you can print a TPU washer.  I also include a parametric Fusion360 file that lets you specify a custom size, so any appropriately sized rubber washer can work.  

Printing

You will need to take care when printing the rollers in a vertical orientation.  I recommend slicing with random seams and a brim.  Carefully calibrate your first layer and use glue/adhesive products to further increase bed adhesion.  

Assembly and Notes

I designed for 625-2RS bearings found in several Voron builds.  I wanted a model that could reuse several of these bearings pulled from my Voron after some maintenance.  I use M5 screws for axles since I think they will be sturdier than printed plastic axles.  Note that the M5 screws will be a tight fit in the holes.  The threads are intended to cut into plastic.

In my picture, I have the Bowden tube exiting from the top of the spool.  I did this for easier loading and unloading, but a bottom exit would be better.  

A dry box can add extra resistance for your extruder to overcome, so be careful when running prints very close to your maximum extrusion rate.  I recommend using a large inner diameter PTFE tube from the dry box to the extruder motor, and installing plastic rims on cardboard spools.  

Wet Filament

A dry box will not dry your wet filament!  Use a dehydrator or filament dryer to actually dry your filament.  A dry box is meant to store and maintain dry filament.  These are the products that I use in conjunction with a dry box to print hygroscopic filaments such as PETG:

• Edit: I no longer recommend the Rosewill dehydrator.  The fan makes an annoying rattling sound after only a dozen spools.  
• Desiccant: https://www.amazon.com/Dry-Premium-Quality-Indicating-Packets/dp/B07K4PRGZ6/
• Hygrometer: https://www.amazon.com/AikTryee-Temperature-Hygrometer-Thermometer-Fahrenheit/dp/B08PVLF8LD/

Thanks for visiting, and enjoy!