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Guide: How to Make a Filament Dryer for $30

When it comes to 3D printing, I am notorious for leaving my filament exposed to the environment. With rolls left out for weeks (sometimes months) at a time, they start to absorb moisture from the air and ruin the print quality, long before I ever decide to use them again. This is where the Filament Dryer comes into use, basically evaporating the absorbed water from the filament over the course of several hours.

Although some materials are more prone to have issues than others, it doesn’t take long for plastic to deteriorate without proper storage. I have bins filled with desiccant packets and dehumidifiers, but it only takes one decent sale before these are filled up to capacity.

Filament Roll Storage Container

There are of course several other popular options to restore spools of filament, such as baking it in the oven or leaving it in rice, but the results are hit or miss with these methods. The Filament Dryer by comparison is dead simple to use and has a near perfect success rate. After destroying several rolls with inconsistent oven temperatures, I made one of these and haven’t looked back.

Purchased Parts List

Food Dehydrator WFD100W - $

Printed Parts List

Dehydrator Tray Extension (Large Printers)
Dehydrator Tray Extension Parts (Small Printers)

Inspiration

PrintDry Filament Dryer
The PrintDry company has been selling a Filament Dryer for years, priced at $99. It is recommend by MatterHackers and sold on Amazon with glowing reviews, where it does in fact work great. Nonetheless, it isn’t exactly the affordable solution we makers are eager to purchase. Most of us would rather hold a blow dryer to our spool for hours than fork out that kind of cash.

The good news is, this isn’t some innovative new solution the PrintDry company designed. In reality, it is nothing more than a $30 food dehydrator from China, re-branded and marked up over 300% for the 3D printing community. Sure, they make a few enhancements like spool sized chambers with filament feeder holes, but the product itself is nothing more than a standard kitchen appliance.

If you really want the few extra bells and whistles, just buy the individual parts from them instead. You can pickup their clear spool chambers for $28 and the filament feeder for $10.

Instructions

There are actually two models of this food dehydrator available from Westinghouse, WFD100W and WFD101W, the second of which is used for the PrintDry Filament Dryer. It’s a bit larger than the base model and offers a temperature range of 35-70° Celsius, but they are otherwise quite similar in design and features. For our purpose, the cheaper model will do just fine and save us a few bucks as well.

The Westinghouse Food Dehydrator comes with 5 plastic food trays that sit too low for a standard filament spool. One potential option is to use a box cutter, and trim away the bottom of each tray, leaving just the outer walls to contain the heat. While this will work, it’s a tedious process and ruins the ability to use it for food at later time.

Instead, we’re going to make our own printed tray(s) and leave the sharp tools for another project. Just print out one of the tray extensions (linked above) from Thingiverse, where these are designed to encompass a full sized spool and fits the Westinghouse WFD100W perfect.

Assembly

There isn’t much assembly work involved, everything snap fits together with a simple notching system. As were not using the standard trays for their intended purpose, it’s just a matter of replacing them with a printed extension instead. For the sake of demonstration, we will take a brief look at the final result.

As mentioned previously, these notches allow for you to stack trays in any desired combination. My personal preference is to place one clear tray on the bottom that acts as the base. I then seat the printed tray extension, followed by another clear tray and the vented lid on top.

Note: For those with multiple rolls of filament, you can print several tray extensions and stack them to dry several spools at once.

The original trays are vented, allowing the heat to pass through and rise towards the top. This works to keep a stable temperature around the filament and continually dries it out.

Temperature Settings

The Filament Dryer has a single control knob that operates both the power and temperature. As soon as you rotate the knob clockwise, the unit turns on and starts generating heat. Depending on the type of filament you need to dry, the temperature you use will need to be adjusted. It’s important to pay attention to the material’s glass transition temperature, where drying it at or above this level of heat can permanently change and ruin the plastic.

Glass Transition Temperature: the temperature range where plastic transitions from solid to a soft, rubbery material.

Each setting is displayed on the front in Fahrenheit, starting with 104° (40° C) at the ON position and reaching a maximum of 158° (70° C). PLA for example has a much lower glass transition temperature than other materials, where this requires less heat to dry the filament.

Filament Dryer Temperature Knob

The table below provides suggested drying temperatures and the estimated duration, although each material will vary by manufacturer. It is recommended to air on the side of caution, using less heat for longer periods of time if you are unsure.

TypeTemperatureGlass TransitionDuration
PLA122° F140-150° F8 Hours
PETG140° F165-175° F4 Hours
ABS158° F220-230° F4 Hours

Filament Dryer Results

When I was first looking into this project, I came across a someone on Youtube that had tried a similar approach. As the video came to an end, he promised to share before and after shots once he had actually used it. Of course there was no follow-up results ever posted, leaving myself and the other viewers wondering if it was a success at all. Having now tested it for myself, I can confirm that it does indeed work quite well.

In the photo below, the print on the left was taken after eSUN White PLA+ had been left out for several weeks. The flat surfaces are actually very bumpy to the touch and have visible deviations in the layers. The print on the right was made after drying the filament for 8 hours, effectively removing almost all moisture and creating a much smoother surface.

Filament Dryer Results

10 thoughts on “Guide: How to Make a Filament Dryer for $30

  1. How about using those vacuum seal bags to store the spools? I’m talking about the bags meant mainly for storing clothing and blankets where you connect a vacuum cleaner to suck out the air. I was going to get bags that were small enough for one or two spools so that I wouldn’t be exposing too many spools at a time.

    1. That is an excellent way to store filament that hasn’t been exposed to the environment for an extended period. I use a combination of plastic bins with dehumidifiers and plastic bags with silica packets, but have been considered some of those vacuum seal bags for easy preservation as well.

  2. Thanks a lot for this Brett, I put one of these together a couple of days after reading your post. I printed the tray extensions with PLA and super-glued them together for rigidity and to keep the airflow inline. So far it is working great and I can see a difference in my prints.

    1. Glad to hear it Dave, these things definitely do a great job of restoring old spools of filament! Since I still do a very poor job of properly storing my filament, it has become habit for me to pop them in the dryer in advance before I plan to use them. My girlfriend also keeps the apartment pretty cold so it doubles as a space heater for my office as well.

  3. I tried drying a spool in my oven at 170 f. That’s as low as it will go and the spool deformed and ruined the filament. I tried again in a toaster over which was temp controlled by an external controller. Temp never went over 150 f. Still deformed. What am I doing wrong?

    1. Hi Bob,

      I’m going to assume you are using PLA based on the temperatures you mentioned. 170 is definitely too hot for PLA, the recommended temperature range is 140-150°F at most. I’ve used an oven a couple times at that temperature as well, leaving the oven door open and continually rotated the spool every few minutes. The food thermometer read about 143°F with the door open (this obviously had cooler temperatures in the front with the door open, which is why I rotated it). I personally would not use the oven again unless you have access to one that doesn’t have the minimum temperature setting of 170, but that has been required of manufacturers for about 20 years so it would have to be an old oven.

      As for the toaster oven, I have a feeling this suffers from the same problem as the oven. Temperatures are never exact with these appliances, they can fluctuate drastically from what has actually been set, especially warmer in areas where the heating elements are. The filament you are drying will play a role, where each manufacturer uses different additives and some melt hotter than others, but for the most part a stable 140-150°F is a maximum.

      Have you considered just picking up a food dehydrator and using that (like shown in the guide)? They are very affordable these days, have much more stable temperatures and the venting holes at the top help prevent it from getting too hot inside. Just to be on the safe side, I usually run mine right above the 126°F mark on the knob and have had perfect results every time.

      1. My problem is not with the filament but the spool. Even below 150 f the spool deformed. The toaster oven was being controlled by an external controller, not the regular one. Temp was measured with a precision thermocouple probe accurate to .2c.

        1. Hi Bob,

          That is bizarre, I have definitely never heard of that before, even baking mine in the oven at PETG drying temperatures didn’t experience any deformity in the spool itself. Who is the filament manufacturer that you are using? I suppose you could remove the filament and re-spool it on something like the Master Spool but this sounds like it is likely an issue with a specific manufacturer above anything else.

  4. The spool that failed in my oven was Sunlu PETG’.
    The one that failed in the toaster was some sort of generic EU PLA that shipped with my Prusa MK3. I figured it was a good test subject since I won’t run it through my printer. The filament is of such poor quality that I had several bad jams to the point I had to replace several of the extruder parts. Once I started using better filament, my problems went away. I use mostly Matter Hackers ABS and PETG. The Sunlu was because I couldn’t get the color I wanted from Matter Hackers.

    1. Hi Bob,

      There is simply no way that the spools should have a lower melting point than the filament themselves, and unless they are perhaps coming in to direct contact with a heating element, I can’t fathom how this is happening. With that said, if you use either of these filaments on a regular basis and need to dry it, you may want to look at re-spooling it first or just do a prolonged bake at very low temperatures (such as 24 hours @ 100° F).

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