Filament Spool Desiccant Canister

A desiccant canister designed to be mounted in the center of a spool of filament during storage to help keep the filament dry. The canister has a lock-ring which threads onto the opposite end from the cap, after the canister has been inserted into the center of a spool of filament, which secures it in place and prevents the canister from falling out.

The cap and lock-ring have been designed to be low-profile so the spool will still fit inside the original packaging bag and/or box with the desiccant canister in the center.

There are two version of the cap; a standard cap and one that accommodates one of the common round hygrometers (thanks to zijiewang178 for the suggestion!).

Inspiration for this design was taken from the containers designed by gdrag and Malolo. The lock-ring design was inspired by Repkord's RepWinder.

Print Recommendations:

• PETG or another material with higher temperature resistance (so you don't have to worry about removing the canister when you put your spools in a filament dryer).
• Use a 0.4mm nozzle* at 0.2mm layer height.
  *I no longer recommend using a 0.6mm nozzle because what you gain in reduced print time, you lose in print quality. Through additional testing over time, I've determined the resultant print quality is much better and requires less post-processing (if any) when printed with a 0.4mm nozzle as opposed to a 0.6mm nozzle. With input shaping, the print time difference between the two is negligible; about 40 minutes per complete canister (not including the funnel).
• It's recommended to use a height range modifier on each threaded part to drop the layer height down to 0.1mm for the threaded areas. While not required, it does improve the finish quality of the threads.
  • Height ranges are as follows:
    • Canister = 0-10mm & 59-70mm.
    • Cap = 2-12mm.
    • Lock-ring = 2-10mm.
    • Funnel = 24.5-35mm.
• Print the funnel upside down — threads facing up.
• 2 perimeters.

Assembly & Use:

• The cap and lock-ring have opposing threads, so you can't mix them up and accidentally spill all of your desiccant everywhere.
• Use the funnel for filling; fill to about 2-3mm below the top of the funnel neck.
• When screwing on the cap, you may need to jiggle the canister a little as it threads into place to coax the desiccant beads out of the thread path.
• The underside of the flange on the cap should be flush with the top of the canister. If you can't get the cap to screw on all the way with a little jiggle-jiggle, then the canister may be over-filled; pour a little out and try again.
• Insert the filled canister in the center of a spool of filament and secure it by threading the lock-ring on from the opposite side.

Hygrometer Cap:

• For the hygrometer to fit correctly in the cap, you will need to slightly bend the lock tabs out away from the body of the hygrometer — be careful not to bend them too far, or they will break; ask me how I know.
• Once the hygrometer is inserted into the cap, you may find it necessary to use a small flat-head screwdriver to again bend the tab outward to get it to engage on the underside of the cap, holding the hygrometer in place.

• Fill the canister with an appropriate amount of desiccant, allowing enough room for the hygrometer when the cap is fully seated.
• Available on both the standard cap and the adapter cap for Sunlu spools.

Notes:

• 2 canisters with caps and lock-rings (no funnel) will fit on the MINI/+ print bed.
• 3 canisters with caps and lock-rings (no funnel) will fit on the MK3/S/S+ or MK4 print bed.
• ?? canisters with caps and lock-rings (no funnel) will fit on the XL print bed. I don't know because I don't have one and that makes me sad.

Change Log:

• 30AUG2022: Minor description adjustments; added 3 additional photos.
• 13SEP2022: Added shorter (58mm) canister and adapter cap & lock-ring for Sunlu spools (72mm ID).
• 05FEB2023: Added thick-walled funnel.
• 26MAR2023: Added hygrometer cap.
• 29AUG2023: Added canister extension ring to convert Sunlu (58mm) canister to standard height.
• 23DEC2023: Added adapter cap with hygrometer cutout for Sunlu spools (72mm ID); thanks to Reika for the suggestion! Added remix “differences” description. Updated some text in the description. Corrections to file naming.
• 15JUL2024: Updated canister model file with increased clearance on the threads to reduce friction in these areas and limit or eliminate the need for any post-processing or break-in; thanks to TheSpyWhoLovedToBake for sparking the idea to revisit and improve this area of the model. Updated description to remove 0.6mm nozzle recommendation (with explanation). Updated G-code files. Updated cover photo.

While the general concept is the same and I used these models as inspiration, I opted to redesign the canister from the ground up, adding additional features like a lock ring to keep the canister retained within the spool, adapters for different types of spools, and the ability to use a common hygrometer with the canister if so desired.