Buying a filament dryer: what really matters
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Damp filament crackles, strings and makes brittle parts. A filament dryer solves this more reliably than an oven or a radiator. The devices differ greatly, though, and the most important difference is often only in the small print: the maximum temperature.
Which temperature and time each material needs is covered in the article Drying and storing filament. This article is about which device is suitable for the job. Specific models with temperature, spool count and price are in the filament dryer comparison.
The types of device
Dry box with heating
The most common form: a box for one to four spools with a heating element, fan, temperature controller and usually a timer. The spool rests on rollers, and the filament can run straight out through an opening to the printer. Simple single-spool models often only reach 50 to 70 °C. Larger or higher-quality devices manage 80 to 85 °C, and a few models over 100 °C.
Converted food dehydrator
A fruit dehydrator with round trays. To make a spool fit inside, you take out trays or print a ring extension. This is cheap and often surprisingly effective, because dehydrators are well ventilated. Drawbacks: the temperature display is often inaccurate, many devices only go up to about 70 °C, and printing directly from the device is not intended without modification.
Dryer with feed-through for printing
Many dry boxes have an opening with a tube connector. This way you dry and print at the same time, and the spool stays warm and dry throughout the print. This is especially handy with nylon, PVA and TPU, which absorb moisture again after only hours in the air. Look for free-running rollers, otherwise the resistance at the extruder goes up.
Drying integrated into the multi-colour system
Some multi-colour systems heat the spool compartment. This saves a device and space. The temperature limits differ, though: according to manufacturer figures, systems such as Bambu Lab’s AMS 2 Pro and Anycubic’s ACE 2 Pro reach up to 65 °C, and the single-spool AMS HT variant up to 85 °C. With the AMS 2 Pro, the maximum value only applies in a sufficiently warm environment. That is enough for PLA, PETG and TPU, but not always for nylon and PC. More on these systems under Multi-colour printing.
Buying criteria
Maximum temperature
The most important criterion. For PLA, PETG and TPU, 55 to 65 °C is enough. For ABS and ASA, but above all for nylon and polycarbonate, you need 70 to 80 °C. Check two things here:
- Is the temperature in the data sheet or only on the packaging? Some figures refer to the heating element temperature, not the air at the spool.
- Is it reached at normal room temperature? In a cold cellar, a weak device often manages significantly less.
A cheap thermometer in the box shows you what actually arrives. With spools made of cardboard or thin plastic, pay attention to their temperature limit.
Number of spools
One spool is enough if you mostly print one material. For multi-colour printing or several printers, two to four spools are practical. Some devices with four slots have two separate chambers, so you can dry two materials at different temperatures. Also check whether 1 kg and 2 kg spools and wide cardboard spools fit inside.
Active air circulation and moisture removal
Heat alone does not dry. The moisture has to leave the box, otherwise the humidity inside rises and the filament absorbs it again as it cools. Look for a fan that circulates the air, and for vents or a valve that carries away humid air. Devices without a fan often heat unevenly: the outside of the spool is warm, the inner layers hardly.
Hygrometer
A built-in humidity sensor shows whether the drying is working. The values are a rough guide, not an exact measurement of the filament. If it is missing, a small digital hygrometer for a few euros will do.
Spool rollers
Ball-bearing rollers turn more easily than simple plastic rollers. This matters when printing directly from the box. Some devices rotate the spool themselves during drying so that it warms evenly.
Noise
The fan often runs for many hours, overnight in the case of nylon. Manufacturers’ noise figures are rarely comparable. If the dryer sits in a living space, it is worth looking at reviews.
Other points
Timer with automatic shut-off, an easily readable display, presets for materials, a tight, insulated construction and CE marking. A device that heats for hours should not stand near flammable material, see Safety.
Price ranges
| Type of device | Spools | Max. temperature approx. | Price approx. |
|---|---|---|---|
| Simple dry box | 1 | 50 to 70 °C | €30 to €70 |
| Food dehydrator | 1 to 2 | up to 70 °C | €30 to €60 |
| Mid-range dry box | 2 to 4 | 70 to 85 °C | €70 to €200 |
| High-temperature dryer | 2 to 3 | up to 110 °C | €200 to €350 |
| Multi-colour system with drying | 1 to 4 | 65 to 85 °C | €100 to €350 |
Prices fluctuate greatly with promotions. When comparing, the price per spool slot matters less than whether the device reaches the temperature for your materials.
After drying: store properly
A dryer achieves little if the spool then lies open for weeks. In short:
- Put the spool in an airtight box with a seal or a vacuum bag.
- Add desiccant such as silica gel, ideally with a colour indicator.
- A small hygrometer shows when the desiccant is saturated.
There are storage boxes with a feed-through that you print from directly. For sensitive materials this is a cheap addition to the dryer.
Continue with: Drying and storing filament for temperatures and times per material.