Filament Dryer and Storage Container

by EricYoung, published

Filament Dryer and Storage Container by EricYoung Nov 26, 2012

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***UPDATE July 13, 2013
After using my own dryer for a long time now it's become apparent that cycling certain filaments (drying then using then drying again and so on) may have adverse effects. I've not done any serious testing and this is just based on my own experience and observations, but basically the translucent/transparent PLA can become more brittle and develop an increased tendency to snap. Opaque PLA's don't seem to be affected from what I can tell. I don't use ABS or other materials so I can't speak to those.

For the translucent PLA I've been able to get around the brittleness by stretching it prior to printing, which just entails taking a certain length of filament (usually about 20ft long) and clamping the free end to something off the ground, then using the weight of the spool end to stretch it and place the spool also above the ground so that the stretched length is subjected to gravity. I let it sit like this for a day or so before printing and it seems to work fine after that***

This thing is for removing moisture from and storing your 3D printer filament. Basically it's just a container with a low Moisture Vapor Transmission Rate and a light bulb for a heater. After a month of use it appears to work nicely and the components to build it totaled about $28 plus a trip to two stores.

In my limited 3D printing experience it seemed to take a spool of filament about a week out in the open before it sucked up too much moisture to produce decent prints (the beginnings of my prints seemed to get bubbly and I attributed it to moisture, though I'm not 100% sure that was the cause). My oven at home doesn't go below 200F, so that drying option was out. WillWorkForPlastic from the RepRap forums started a thread about building a 'dry box' for filament and Sublime mentioned that welders use a 25 watt light bulb inside an enclosed container to keep their welding rod dry. I wanted to make an inexpensive version for myself and thought others might want one too.

If you want to make only a storage container instead of the dryer you can ignore all the items on the BOM besides the bucket, lid, desiccant and silicone sealant. Actually the sealant is probably overkill since the 'Gamma Seal' lid is air-tight.


The PDF drawing attached has all the info you should need to make one of these including Bill of Materials and assembly instructions. If there are any questions or I missed something on the drawing just let me know.

To use it you put your moist filament inside with the desiccant and turn on the light for 3 hours or so. Less time might be adequate too - I've not done any testing with other times and know that 3 hours does the job so far.

Links to some lesser known purchased parts from PDF drawing:
Gamma Lid - Items 3/4:

Silicone Sheet/Pad - Item 11:

Desiccant - Item 13:

E27 Socket - Item 6:

The last picture shows what happens when your filament gets too hot, so be sure to keep it at least a few inches away from the bulb when drying.

Use this at your own risk and be careful of getting anything flammable at low temps next to the hot bulb for any long period of time.

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Jan 18, 2015 - Modified Jan 18, 2015

I like your idea, but I did not want to put so much time in such an elaborate setup. Also, I needed a solution where I could stack a lot of spools. So I came up with a simple alternative.
I simply use a vacuum bag, together with a special type of silica gel, with moisture saturation indicator. The vacuum takes care to evacute the ambient air (with moisture in it), and the silica absorbs any remaining moisture contained in the filament. The color indicator tells me easily when to replace the silica. Simply dry the moist silica in the oven (it can be re-used indefinetely) and put it back into the vacuum bag once dry.
I have written a small article about it on my website. Check it out if you are interested: http://3dprintingforbeginners.com/how-to-store-3d-printing-filament/
I would love to hear what you think about it.

Many polymers are sensitive to (UV) light, one way used to stabilize plastic is to add a colourant that absorbs the harmful light, for instance carbon black...

Perhaps exposing the filament to all that light simply accelerated the ageing?

On youtube, there is an interesting video on silica-gel as a desiccant:

I've had brittle transparent PLA as well... and have never tried drying it out... so it may just be something the material does as it ages, not specifically your process..

Thanks, but the initial idea really came from WillWorkForPlastic over in the RepRap forums :)