Printing dry box for large spool holder

As if the world needed another dry box - however I could not find anything to keep hygroscopic filaments dry for long print jobs. Printing out of the my electric filament dryer was not an option, as due to the friction of soft filaments like TPU the prints regularly failed due to lack of feed from the extruder. 

The whole thing is designed to guarantee the least possible resistance, with ball bearing and filament outlet swivel mount. It's not meant to be storage box, for this you can get yourself a cornflakes container. 

Once you dry the filament in a filament dryer, it will keep it dry for days with the added silica gel packs thrown in the bowl of the base. 

This was designed to fit in my wall mount large spool holder design, to feed the printer from above avoiding side mounts and long winding PTFE tubes. The first photo shows it in action, for a 12 hour TPU print. After the print, the swivel mount can be covered with a cap - the end of the filament sticks into the cap for easy retrieval. I will probably design a overhead holder for other printers like Bambulab H2D once I get round to it. 

The box has a build in hygrometer to monitor humidity. Closure is with 2 latches with over-centre mechanisms. The gaskets are soft TPU. The roller on ball bearings will accommodate for most 1kg spools. 

Printing:

the case and lid are printed in PLA-CF with 0.4mm nozzle recommended, due to warping issues with the large parts only attached by a small surface area (ask me how I know...). Also for the base and lid, a brim with 0mm brim-object gap is recommended for the same reason. Print base and lid on their mating surface. Build plate adhesive or a cold plate would help, too. Support on build plate only for base and lid, the other parts do not need support. 

The other parts could be any PLA, or same PLA-CF. 

The gaskets are printed with the softest TPU available, I suggest TPU 85A (or TPE 83A if available). The base gasket has to compressible, print with only 1 wall, and "ensure vertical shell thickness" set to none, so the gasket is mainly hollow. 

Assembly:

Screw the hinges to the base and lid - no threaded inserts needed

Insert the hygrometer into base with seal, push in hard and twist 15 degree to lock. 

The swivel mount will need  some silicone grease added, to move smoothly. Adjust tension with swivel mount screw so it still moves freely. Insert Bowden tube coupler while holding the ball from the back side with a flat screwdriver. 

Superglue the bearings to the roller axle.

TPU seal for base can be just pushed in, with the spiky part upside. 

Mount the latches with M3 screws, paying attention to the hinge and hinge link orientation so that the screw head recesses are pointing outwards, otherwise impossible to fasten. 

Bill of materials with example links:

400g of PLA-CF, PETG-CF might work

20g TPU 85A, or TPU95A

Hygrometer

2x ball bearings 6700ZZ 10x15x4mm

1x Bowden tube coupler M10 

8x M3 x 10mm hex bolts for the hinges

4x M3 x 30mm hex bolts for the hinges and latches

2x M3 x 25mm hex bolts for the latch links

Silica gel packs

Short piece of PTFE tube