The Best Filament Dryers – And How to Make a Drybox!

Printing with wet filament is one of the most common and least analyzed causes of 3d printing failures. This article studies different options to remove moisture from filament spools and keep work material in the best of conditions, from solutions employed by professionals to available homemade alternatives.

The best filament dryer is the SUNLU S1, due to its excellent price-quality ratio. Likewise, it includes an adjustable timer and even allows you to use the filament to print during the drying process. Its only con is the relatively low maximum attainable temperature, of around 131F. Since nylon requires temperatures close to 176F for better drying, in those cases it is more suitable to go for a dryer like the Eibos 3d Cyclopes.

What are filament dryers?

Usually, when there are printing problems we focus our efforts on finding the causes of our printer’s poor performance in the hardware of the machine. We try to level the heated bed, adjust the belts, lubricate the guides or calibrate the stepper motors.

Failing to improve its performance, we change the values set in the slicer by means of modifying printing parameters or even the firmware of a printer that worked fine for a long time.

In this way, the analysis of a fundamental part in the 3d printing process is left aside: the filament. Its preservation is essential to achieve a good-looking piece and as well avoid problems related to lack of extrusion or an irregular surface finish.

Moisture is said to be the worst enemy of filament since plastic absorbs water and as a result the properties of said material change significantly, reducing the quality and resistance of printed pieces.

Once the filament is wet, it is necessary to remove the water molecules from it before using it. There are many ways of doing so; one of them is by means of filament dryers. These are devices specifically designed to heat the filament to a suitable temperature, causing water to evaporate and preventing the material from melting inside the spool.

Are filament dryers really useful?

Some years ago, there was no commercial equipment to dry filament so many users dried their filament with more rustic homemade means. For this reason, many of them do not find much use in current filament dryers.

Furthermore, the drying time takes several hours so they are not very useful in everyday usage. Users should anticipate which spool will be used the following day and check if it is wet before printing a piece, something that does not occur very often.

On the other hand, popular filaments such as PLA or PETG absorb moisture in smaller amounts unlike Nylon or TPU so you can prevent them from getting wet just by storing them in airtight containers (preferably with small bags of silica gel).

The moisture absorption mechanism is another factor to consider. Since it is firmly wound, the filament that is first affected by moisture from the environment is the one found in the first turns of the reel.

In this way, the inside of the spool is protected and does not get wet (within certain conditions), so a quick solution is discarding the first turns of the spool (a few inches of filament) and using the remaining filament as normal. This would make it possible to dispense with filament dryers completely.

In conclusion, the usage of dryers will basically depend on the users’ needs, the type of pieces they print, and the degree of organization during the printing routine.

The best filament dryers

Though there are homemade methods to dry filament, dryers guarantee a homogeneous and replicable drying. This is how every 3d printing professional who does not wish to waste valuable time improvising decides to purchase a dryer. Within the wide range of filament dryers available on the market, the following are the most outstanding:

SUNLU S1


This dryer, small in size and very easy to operate, is compatible with most of the best-selling filament spools around the world. In order to use it, it is only required to set the desired time and temperature. It is one of the cheapest dryers on the market since its price is usually around $50.

Incorporated functions:

  • Adjustable timer
  • Temperature regulation (between 95 and 131 °F)
  • It can be used while printing

Specifications

  • Max spool size: 8.26 x 3.34 in
  • Max continuous usage time: 24 hours
  • 1-year warranty
  • Quiet operation (less than 10 dB)

More information about it is in the following link.

eSUN eBOX

This compact dryer similar in size and appearance to the SUNLU S1 offers users 3 essential functions: it heats and dries filament before and during printing, protects it against dust and moisture when the printer is not used, and also indicates the inside weight of the spool, what allows users to know the amount of remaining filament at all times. Its approximate price is USD 59.

Incorporated functions:

  • Adjustable timer
  • Temperature regulation (up to 176 °F)
  • Spool weight indicator
  • It contains and dries silica gel bags (included)

Specifications

  • Max spool size: 7.87 x 2.87 in
  • Power: 36 W
  • Power source: IN: 110/220 V – OUT: 12 V 3 A

More information about it is in the following link.

EIBOS 3d CYCLOPES

This dryer of considerable size can contain up to 3 spools of 1.10 lb inside. It has a roller base with 8 bearings, which minimizes the friction while printing and avoids clogging or loss of steps in the extruder motor. Its design focuses on ease to use, constant monitoring of filament conditions, and operation safety. It is made of flame-retardant material and its closed-loop control system manages the usage of electrical energy efficiently.

Its approximate price is $140 and it is available in 110 and 220 V versions, along with corresponding adapters for power outlets.

Incorporated functions:

  • Adjustable timer
  • Temperature regulation (up to 158 °F)
  • It can be used while printing (it requires changing the PTFE tube to use 0.11 in filaments)
  • Moisture level monitoring

Specifications

  • Max spool size: 1 spool of 8.54 x 6.85 in or 2 spools of 8.54 x 3.14 in
  • Max continuous usage time: unlimited
  • Security certificates
  • Quiet operation (less than 10 dB)

It will usually set you back around $140, but you’ll be able to find it cheaper from time to time (you can check it out in the following link).

POLYMAKER POLYBOX Edition II


This container is a combination between a heat filament dryer and a Drybox. Its main function is keeping moisture levels below 15% and it can be used while printing. It can contain up to 2 spools of 2.20 lb each. Since it is not an active dryer, it does not contain an electric heater inside but instead 2 reusable silica gel bags of 0.22 lb to reduce the moisture of the filament and keep ideal conditions while printing. Its approximate price is USD 80.

Incorporated functions:

  • Digital hygrometer
  • Temperature indicator
  • Low friction roller base

Specifications

  • Max spool size: 4.72 in (diameter) x 4.72 in (spool width)
  • Digital display power supply: 1 LR44 battery

More information about it in the following link.

Alternative methods to dry filament

The essential principle of filament drying is the circulation of hot dry air in a closed area, in order to evaporate the water inside the polymer structure.

If a commercial filament dryer is not available, there are other methods that fulfill the same function with their pros and cons.

Oven

Easily available, ovens present in most houses are a way to dry filament. The technique consists of introducing the roll into the oven, at a moderate temperature for a few hours.

Different kinds of filament require different temperatures:

  • PLA: 113F
  • ABS: 167F
  • Nylon: 176F
  • PETG: 158F
  • TPE: 176F
  • TPU: 122F

Pros:

  • The process is very simple, filament is just “baked”.
  • It is easy to have access to an oven.
  • It does not require special tools.

Cons:

  • Time and temperature come from experimentation, so it is necessary to do several tests before trusting the process.
  • In most cases, getting it wrong means melting a spool completely or making the turns of filament stick together which ruins the entire material.
  • Sometimes the material of the spool is very different from that of the filament. Therefore, it melts first without achieving the desired effect.
  • There is a very big safety risk, which means that you must constantly watch the oven.

Food dehydrator

Food dehydrators are increasingly used in gourmet kitchen, since they allow you to create new plates with dehydrated food such as fruit, vegetables and mushrooms.

They work in a very similar way to filament dryers, through the circulation of hot air around food arranged on metal trays. Thus, they can be used to remove moisture from a wet spool, adjusting the temperature values and usage time.

Pros:

  • Food dehydrators are not as aggressive as ovens, since they are not designed to cook food but rather to heat food progressively and steadily over time.
  • Their size is limited compared to that of ovens, but it is spacious enough to contain most of the spools on the market inside. It even allows you (in some dehydrator models) to place 11.02 lb rolls inside.
  • The timer function is particularly useful, as it allows you to safely use the device at night.

Cons:

  • Hot filament releases gasses that can affect the smell of food or even make it toxic, if the dehydrator is used for both.
  • It is not a common device at home, and its price is higher than that of filament dryers, so it is not convenient to buy one just to dry filament rolls.

If you’re interested both in creating your own gourmet food and removing moisture from your filaments, check out this food dehydrator.

What is a Drybox and how can you build one?

Source

A drybox is a closed container for filaments. It is usually used for certain kinds of filament, which are more likely to absorb moisture from the environment. Some materials such as PLA, which do not normally require a controlled environment, can be affected during days of higher humidity or in generally humid geographical areas.

The purpose of these containers is to keep filament rolls isolated before, during, and after printing and closing almost hermetically the enclosure where one or more spools are placed. A filament outlet must be prepared, which will feed the extruder while using the printer. In addition, a heater with a forced air outlet can be incorporated to improve its operation.

How to build a Drybox easily?

Building a homemade Drybox is very simple and requires very few elements. To get started, the following materials are needed:

  • Transparent or translucent plastic container with a lid (which allows you to see the amount of remaining filament without opening the Drybox). Its minimum height must be 0.39 in larger than the diameter of the largest spool used. The remaining measurements will depend on the number of rolls that you want to place inside.
  • Teflon tube (PTFE)
  • A PVC tube or similar. Length must be the same as the plastic container
  • Some silica gel bags
  • Hot glue gun
  • Screws
  • 3d printed pieces

Assembling consists of gluing or screwing the internal brackets for the PVC tube (to do so they must be printed first). In the following link, you can get some very suitable brackets, on which the spools are hung.

Later, holes are made in the front of the container to place the filament feeders (these can also be printed, using the following file). In case you do not have the necessary o-rings, you can apply hot silicone instead.

Teflon tubes run through the feeders and guide the filament safely, preventing tangles when printing.

Lastly, the silica gel bags are placed within the Drybox and the filament rolls are hung. The ends of each spool are passed through the feeders and finally, the lid of the container is closed. The Drybox is ready to be used, keeping its inside dry and protected from the environment.

Which filaments require a Drybox?

Plastics used in 3d printing are diverse and respond to different needs. Their physical properties can be very different according to the molecular composition of the polymer chains with which they are made.

A particular feature is their hygroscopicity degree, which is the ability of a substance to absorb moisture from the environment.

In general, all filaments made for 3d printing are hygroscopic. When wet, they become brittle and affect printing quality since the absorbed water has a vaporization temperature close to 212 °F while the hotend usually exceeds 374 °F in the simplest of cases.

As it passes through the nozzle, the water suddenly evaporates, generating a small “explosion” that forms an air bubble in the filament. An extrusion irregularity can be observed in the piece, which gives it an unpleasant appearance.

As the material is more hygroscopic, it can retain more water inside in less time, and therefore aggravate this problem. For this reason, some filaments require especially dry storage, and even the usage of a Drybox to avoid dampness when the material is used.

The following filaments stand out for being highly hygroscopic and therefore benefit from being stored in a Drybox:

  • Nylon
  • TPU
  • PC
  • ABS
  • PETG

Ideally, it is convenient to use them in a controlled environment.

Products and alternatives to dry filament

OptionProsConsPrice
SUNLU S1It is the cheapest of them allLow maximum temperatureAround USD 50
eSUN eBOXIt includes the scale functionIts shape can restrict the spool sizeAround USD 60
EIBOS 3d CYCLOPESGreater size and better build qualityIts price can be limitingAround USD 130
POLYMAKER POLYBOX Edition IIUsing it does not mean a risk since it does not have a heaterIt can be replicated at home at very low costAround USD 60
HornoEasy to getIt can melt the filament if it is not controlled properly
Food DehydratorSame functions as specific driersFor its price, it is convenient to buy a filament dryerFrom USD 50

When users conveniently store filaments, the usage of filament dryers can be dispensed with, especially in dry climate areas. Having a dryer in case of need can be convenient, if there is a great commitment to 3d printing or the demand for pieces makes it necessary.

I recommend having a Drybox made in the best possible way and a dryer as cheap as possible for special cases. Alternative methods usually have more cons than pros, which is why they are only recommended in emergencies.

If you decide to buy a filament dryer, the eSUN eBOX is practical, effective to remove moisture from the roll and its price is appropriate. Its spool weight monitoring function makes the difference with the rest of cheap dryers, and it also has a higher maximum operating temperature within its category.

For users with a higher production volume, it may be more profitable to purchase the EIBOS 3d CYCLOPES. This allows them to feed more than one printer at a time with filament in optimal conditions.

Conclusion

Before deciding to purchase a dryer or to build a Drybox, users’ particular needs should be taken into account. For people who occasionally use the printer for a few pieces per month, proper storage of the spools is enough. However, as the intensity of printer usage increases, investment in this type of equipment may be required.

The most demanding materials, such as Nylon or PC, imperatively require the correct drying of the spool at the time of printing and throughout the entire process, so having a filament dryer for them is highly recommended.

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