NoWarrenty Drybox

As i put some brainwork into this, i want to share my drybox setup and make it accessible for beginners.

TL;DR:

Per box (4 spools), print:

• 2 standoffs
• 16 wheels
• 16 bearings
• 4 fittings

Buy:

• 2x M8 threaded rod, you need around 30-33cm per box
• PTFE tubing with 3mm Inner diameter!
• Some athesive like double sided tape or hotglue gun to fix the standoffs on the bottom of the box
• Silica gel pearls 250g per box (i recommend a big pack with 1kg)
• Organza bags, i recommend 2 per box.
• Optionally PTFE spray (If you like printing mechanical parts, its a good idea to have that around anyways)
• Optionally some hygrometer so you can see whats going on in the box. Make sure to check the minimum moisure value (like 10%) and the stepping (in 1% steps).
• Optionally 608 metal Bearings, 16 per box (recommended, see below for considerations)
   

Why Choose a Drybox Like This?

Filaments tend to be sensitive to moisture. Incorporating a drybox into your 3D printing setup ensures your filaments are kept in optimal, moisture-free conditions.

The principle behind this setup is to have your most frequently used filament spools housed within a drybox, ideally positioned above or adjacent to your printer. This strategy facilitates direct printing from perfectly dry filaments. The advantage is clear: instead of the cumbersome process of retrieving a spool from a drybox for printing and later returning it, this method offers convenience and eliminates worries about your filament's exposure to moisture if left out for a few days.

How effective is it?

In my opinion very much. Putting alot of silica gel in the box, like 250g, really hammers own the moisture. Its just a matter of time until the filament and the air in the box get into an equalibrium. The speed of this depends also on the temperature, so if its very cold it may take a much longer to fully dry a spool. Also the outer parts of a spool dry first, so the core may still be wet after some days while the outer 100 meters are dry.

Design Considerations / Tips

Standoff / Spool Holder

In the initial box version, I used a single wooden dowel to suspend all the spools. While this design is more straightforward, it comes with a few limitations:

To replace a single spool, you must lift all the others. If you're trying to replace a center spool, you're obliged to remove one from the side. This process might cause the filament still exiting the box to snap. The wooden dowel creates friction when the printer extracts the filament. This friction sometimes proved excessive for my smaller Voron Zero, while my larger printers didn't encounter this issue.

The resolution to these issues involves installing two rods at the box's bottom, equipped with wheels for the spool to rotate on. The standoffs' central axis is 180mm apart, an ideal distance for the average 200mm spool. The width prevents the spool from slipping off the wheels as it lightens, as the spool sinks deeper between the wheels. I suggest placing the stands as close to the front wall as possible, preventing the spool from moving forward.

A large, thin wall between the towers enhances stability, preventing the towers from bending apart over time when printed with PLA.

The standoffs have multiple holes for the rods so you can choose a height that works good for you. 

Wheels / Bearings

Other dryboxes typically let the spools rotate directly on M8 rods, bypassing bearings. Although I haven't tested this configuration, I speculated that incorporating bearings would result in less friction.

The wheels are flat, avoiding the necessity for perfectly centered alignment with the spool. Metal 608 bearings are the most reliable option while printed ones are more cost effective. When greased with PTFE spray, the printed ones are performing well but they may wear over time, require regrease and cause more friction if you go through a big amout of spools. I have printed ones on most boxes, just the one where i really frequently print out has metal ones. Metal bearings are recommended if you can effort.

Silica Gel

I advise purchasing high-quality, food-grade silica gel beads in bulk. Even though you only need 250g per box, having the ability to exchange them multiple times before regeneration enhances convenience. In my experience, 250g of silica gel maintains the box's dry environment for months, even with periodic box openings. Make sure they are regenerable. A color indicator helps to judge if they need replacment and i found that the orange ones that turn green are not toxic.

Organza bags are convenient for moving the beads while allowing ample air exposure. Alternatively, you can 3D print a container.

PTFE Fittings

The PTFE fittings or filament outlets are entirely 3D printed. I prefer not to purchase items I can readily 3D print myself, and these fittings work exceptionally well. An important tip I've learned is to angle the fittings downward if they're positioned above the spool's center. This adjustment enables the filament to follow its natural bending angle from the spool. Initially, I had fully horizontal outlets, but these caused some filaments to snap inside the box over time.

PTFE Tube

You can clearly use the standard 2mm ID tubes you may have laying around, but keep in mind that these add alot of friction to the filament. While 10cm are no big deal, 30cm are already very noticable. To avoid that and to still have a good routing of the filament, i recommend PTFE tubings with 3mm ID and 4mm OD.

The box

Obviously, it needs to be airtight and large enought to fit the spools into. I got some random boxes from amazon but you may use whatever you want. This drybox setup should work on any box.

Hygrometer

In addition to the tips already on the “Buy” section, i recommend putting all hygrometers you bought and maybe some you have flying around into one single box for some hours to check if they show the same value within a reasonable tolerance.

Cardboard spools

These are a problem with a setup like this, because the rims are not perfectly straigt and may deform. Also, they can easier catch on the rims of the wheels and “walk off” them. I do not recommend using cardboard spools with this setup. There are printable “rims” available that can be attached to cardboard spools to make them work reliable.