mini-makes: filament drybox

putting it together

With the completion of the spool rack, it was time to get the parts and put together the filament drybox itself. Based on my research, a drybox is essential for sensitive filament materials but is also important for more common materials like PLA. For long prints, having the filament exposed to the air may cause it to swell with moisture from the air, which would cause extrusion problems among other things. For me, these parts consisted of

Putting the drybox together was easy enough. The part that required the most work was drilling a hole in the container to fit the gland. I chose a position that would allow me to fit a second hole and gland in the future if I decided I wanted to have access to two filaments for doing multi-color prints.

adhesive gap insulation applied to the edge of the lid
hole drilled
cable gland installed

That’s basically it. Now, all that was left to do was install the PTFE tubing and place the spool rack inside with some silica packets. If you’ve never used a cable gland before, they are sold based on the outer diameter for the opening you’ll install it in. The opening where the tubing is inserted can accommodate a range of diameter and is adjusted by tightening or loosening the nut on the front of the gland. The ones I purchased fit my PTFE tube perfectly when tightened, which kept it from sliding out of the drybox when the printer drew more filament off the spool.

view from inside the drybox

After placing everything inside the container, I realized with how I plan to place my drybox next to the printer, it would be inconvenient to look at the hygrometer. Therefore, I placed the hygrometer unit on the side for easy viewing. Here’s a view of the inside from the top. As you can see, a handful of silica gel packs are also thrown in to help absorb moisture from the air inside the box. The goal, of course, is for the heater to dry the air and lower the humidity inside the box.

does it work?

If I had to do it over again, I would have sized the spool rack to better fit the container. With two spools on the rack, it is a bit tight, so I would have preferred it a bit wider. Additionally, the seal of the box is not very tight. I plan to design some clips that can be placed around the lid that will snap onto the lip of the container to provide a tight seal. It should be a fairly easy print, but getting the dimensions just right will be tricky due to the rounded nature of the lid.

Despite there not being a perfect seal, the drybox still works fairly well. After placing a spool on the rack and closing the lid, I took note of where we started in regards to temperature and humidity. About an hour later, I looked to see how things had changed.

There was an increase of about 5.5 degrees and a decrease of 8% in humidity. Not as much as I would like. I definitely wanted the humidity to be in the 20% range. I think increasing the seal would definitely aid in improving these readings. Of course, it didn’t help that it was a hot and humid day. I suppose the 7 watt heater can only do so much with the aid of a handful of silica gel packs. That being said, 8% in humidity is still a decent amount and having the drybox allows for consistent and stable conditions. I am curious how things will change with clips and a better seal.

This is a fairly simple project and one that can be done in a number of different ways. If you are having trouble with your prints and don’t have a drybox, you should definitely give it a try. It could make all the difference.

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