Filament dehydrator ring and caddy

A good while back, I purchased a cheap food dehydrator, intending to convert it into a filament dryer to save some cost. Like most projects, it landed on the back burner, but it got revived when I received a printer with a larger build volume.

I designed a ring to fit on the dehydrator, but I had some PA6-CF filament that would need to be printed straight from the filament dryer. 

I added a hole in the side of the ring and angled it to let the filament exit without unnecessary bending and friction. I designed the exit to fit a Bowden tube retainer mechanism from Amazon.  This way, the filament could go straight from the dryer right into the print head without ever leaving the Bowden tube.

The PA6-CF I had came on a 3kg cardboard roll, which had so much friction that it required a caddy to ride on. I modeled a caddy with wheels, using a wheel arrangement similar to one published by CT3D, the original makers of the Benchy.  

The caddy has a removable centering hub to accommodate filament rolls with different hole sizes. 

My original version was printed from PLA, but I've had the wheels deform as well as the caddies due to the heat and constant pressure of the heavier spools. 2 of the wheels were bound up, but the caddies, despite exhibiting some creep, are still good. That said, I'd recommend PETG or ABS for the caddy, wheels, and wheel axles (just a bit of filament).

I'm including STP files for easier editing to accommodate dryers with different diameters or to account for filament rolls with different widths. Print your ring height at least at (roll width + 30mm). My filament dryer has an OD of 316mm and an ID of 313mm.

The distance from the surface the caddy rides on to the bottom of the filament roll is 16 mm, and the next ring drops 8mm into the current one, both of these consuming 24mm of the printed height. If you print the rings too low, the next ring will rest on the filament spool and will “ride” on the bottom caddy instead of being supported by the bottom ring's edge due to insufficient clearance.

Printing Instructions:

Print the ring in its proper orientation. Enable support for surfaces less than 35 degrees. This will generate support for the outlet nozzle and the stacking edge at the bottom. This part does not have very thick walls and is exposed to lots of heat for long periods. 

ABS is recommended for this.

Print the caddy and the centering hub facing down. There will be some bridges, but the part has been designed to accommodate that and the bridges does not have  a very long span, so that should print OK.  The 6 wheels should be easy enough unless you print them standing up :) 

PETG is good for this

PETG/ABS
0.4 or 0.6 mm nozzle
3 walls
15% infill

Assembly:

Insert the wheels into their slots and insert a length of filament from the side to act as the axle. The holes are tapered, so you won't feel a hard stop, but it should get progressively harder to move it. Cut the filament off with 5mm sticking out and tap it in like hammering a nail to have it seat securely. Ensure the wheel can move freely. If you're happy with it, cut the filament flush. Once it is cut flush, it is challenging to remove.

Insert the caddy into the ring with the circular ridge on the inside of the wheels - this prevents it from walking about and hitting the walls. Insert the centering hub and place your spool on top. If the centering hub is way too small or too big, you may have to create your own to fit. The seat depth is 7.5 mm and the hub seat OD is 48.7 mm

This is what you should end with.