3D Filament, keeping it dry

Finished insulated filament cabinet loaded with spools, with two humidity gauges reading 20% on the top shelf and 19% in the middle

I built a cabinet that holds under 40% RH.

I wanted a better solution for my open pack filament storage. I have tried several different things over the years. Here is my latest.

I went out to Lowe’s and bought a Project Source 27 inch plastic cabinet:

Project Source 27 inch plastic storage cabinet with two doors, newly bought from Lowe's

I had a couple different size foam sheets that I use as sacrificial when I am cutting up large sheets of plywood.

Sheets of scrap foam board in different sizes, used as a sacrificial surface when cutting plywood

I cut them to fit into the inside of the doors and sides, adhered them with Liquid Nails 10 oz Heavy Duty Construction Adhesive (available on Amazon or at any hardware store):

Foam board cut to fit and glued with Liquid Nails to the inside of the cabinet doors and sides

I added some weight on top and let it dry overnight:

Weight stacked on top of the glued foam while the adhesive cures overnight

I then put the cabinet together:

Cabinet reassembled with the foam insulation installed inside

Then I cut the ends off the shelf. In hindsight I would not do this, I would assemble the cabinet, set the shelves and then insulate. I think it would make the shelf stronger. But…here is what it looked like:

Cabinet shelf with its ends trimmed off, shown inside the insulated cabinet

I had to cut a new slot in to adjust the shelf to where I wanted it, measured so they are all the same and cut out with a razor.

New shelf slot cut into the foam with a razor so the shelf sits at the desired height

Drilled some holes in them to help with circulation:

Shelf with holes drilled through it to allow air circulation

I put the shelves in place and used some Great Stuff Gaps and Cracks Insulating Foam Sealant (available on Amazon or at any hardware store) and foamed any gaps I could find.

Shelves set in place with Great Stuff spray foam filling the gaps around the edges

Let the spray foam dry and put the filament in. I did not put any weather sealing around the doors, I wanted to see how it did first. You can see the slight sag in the 2 shelves. But it worked. You can also see the 2 gauges showing the humidity 20% on top and 19% in the middle. Now that is with fresh desiccant, so the RH will go up.

Finished insulated filament cabinet loaded with spools, with two humidity gauges reading 20% on the top shelf and 19% in the middle

I have 4 of these desiccant boxes on each shelf, as well as one Dollar Tree moisture eliminator.

Desiccant holder boxes and a Dollar Tree moisture eliminator sitting on a cabinet shelf

It has been staying well below 40% which is great for PLA. This is a storage cabinet, not a drying cabinet. When it gets closer I will re-generate the desiccant and see how it goes.

Line chart of cabinet relative humidity readings, rising from about 12.5% on 11/04 to about 26% on 11/10

11/04 started at 12.5% RH 11/10 we are at ~26% RH.

The chart shows 12.5% – 45% RH on the left column and dates starting with 11/04 to 11/10 on the bottom. You can start to see a gradual humidity increase.

I will wait and see how often I need to change out the desiccant, I am hoping for once every 30 days. If I do it again, I will build it, set the shelves how I want them and then add the foam board and spray foam.