Filament dryers

The two dryers, manufacturer photos: the SUNLU FilaDryer S4 on the left and the Royal Catering RCDA-500/15S on the right

Royal dryer on the left and Sunlu S4 on the right on a shelf in the outer part of the 3D printing room

What it is

Filament takes up water from the air, and wet filament prints badly. Drying it takes hours, and hours in an AMS means a printer nobody else can use. So real drying happens here, in the hallway, before you print.

When to dry. How fast filament gets damp depends on the brand and on the humidity, and many spools print fine after weeks in the open. Dry a spool when it shows the signs: bubbles, strings, weak layers, or popping and crackling at the nozzle.

The AMS can dry filament while it prints, but it automatically does so at a lower temperature, so that the filament does not soften in the AMS drive system. That makes it much slower than drying at the right temperature here, and the filament it feeds early on has not had time to dry, so the first couple of hours of your print can come out damp. If a spool needs drying, dry it in a filament dryer before you print. See Bambu Lab AMS 2 Pro and Bambu Lab AMS HT.

Who may use it

Module 2, after Module 1. Your spools must carry your member label.

Which dryer to use

These are preferences, not rules. What matters is the temperature: if one dryer is busy and the other is free, use the free one, set to the right temperature for your filament. Anything that needs more than 70 °C has to go in the Royal dryer.

Temperatures and times. Follow the dryer's own instructions and the drying temperature and time your filament's maker recommends, which you find in that filament's technical datasheet on the maker's website. The table below is Bambu Lab's published guidance, for reference, not room rules.

Setting a dryer

Put your spools in, close the lid or door, then set the temperature and the time. Each dryer has its own printed instructions next to it. This is the short version.

Drying overnight? Set the time to end when you expect to be back. When the time runs out, the dryer switches off and your spools start taking up moisture again as they cool. A cycle that ends at 3 a.m. has undone some of its work by the time you collect your spools at 9.

Sunlu S4 (up to 70 °C)

Sunlu S4 control panel showing PV 49 °C, SV 50 °C, RH 21%, PLA, MO 1 and the SET, up, down and power buttons

1. Press the power button once to switch it on. (Press it twice quickly to switch it off.) It starts drying straight away with whatever settings it had last time, so set yours at once. Changes take effect while it runs.

2. Press SET to step through the settings. The one you are changing flashes. Use ▲ and ▼ to change it.

3. SV is the temperature it will heat to. Set it for your material.

4. Time is how long it will run. Set the drying time.

5. MO is the mode. Check that it shows 1, which means the dryer switches off when the time runs out.

6. Leave the other settings alone (°C/°F, the light bar and the filament type).

7. Check the display: SV and the time show your settings, and the time is counting down.

The S4 has built-in filament presets. They run cooler than Bambu's figures in the table above, so drying takes longer, but they are a safe fallback when you have no figures for your filament.

Royal dryer (Royal Catering RCDA-500/15S, up to 90 °C)

Royal dryer control panel showing 50 °C, light, time and temperature icons, up and down arrows, and the ON/OFF button

1. Hold the power button for about a second to switch it on. It beeps and the panel lights up. (Press it again to switch it off.)

2. Press the temperature button. The value flashes. Use ▲ and ▼ to set it. It changes in steps of 5 °C.

3. Press the time button. The value flashes. Use ▲ and ▼ to set it. Each press changes it by 30 minutes. Hold the button to change it by a whole hour. The longest setting is 24 hours.

4. Wait about 5 seconds. It starts by itself.

Sharing the dryers

• First come, first served.

• If there is space in a cycle that is already running, you may add your spools. You may never change the settings of a run in progress.

• If the temperature is wrong for your material, use the other dryer if it is free, or wait until that run has finished and its owner has collected their spools. Don't turn it down.

When you take filament out

• Let spools cool for 5–10 minutes before loading them into an AMS. Warm filament is soft and gets squashed in the feeder gears.

• Check the spool and filament: nothing warped or damaged, nothing stuck together, and the filament unwinds freely.

• Seal it straight away in a bag, or load it straight into a closed, latched AMS for your print. At normal indoor humidity, Bambu says freshly dried filament can start printing worse within about 2 to 12 hours.

• Drying the same spool over and over can make some filaments brittle. Dry it once, then keep it sealed.

Storing filament

Dried filament stays dry longer if it is sealed, so you need to dry it less often. A spool fits well in an IKEA ISTAD zip-lock bag, in the 4.5 L or 6 L size: squeeze the air out and close it. You can also buy vacuum storage bags made for filament. A desiccant pack in the bag helps keep it drier, but you don't have to use one. Either way, the bag goes in your member box.

The most important rules

1. Pass Module 2 first. Label your spools.

2. Dry before you print, and never tie up an AMS, and with it a printer, just to dry filament.

3. The Sunlu S4 (up to 70 °C) is preferred for PLA, the PLA supports and PETG, and the Royal dryer for anything hotter, such as ABS and ASA. If one is busy, use the other at your filament's temperature.

4. First come, first served. You may add spools to a run that has space, but never change the settings of a run in progress. If the temperature is wrong for your material, use the other dryer if it is free, or wait.

5. Set the temperature and time from your filament's datasheet, or use the S4's preset if you have none. On the S4, check that MO shows 1.

6. Overnight? Set the time to end when you expect to be back.

7. After drying: let spools cool for 5–10 minutes, check them, then seal them in a bag or load them into a latched AMS for your print.

8. Fire or an electrical fault: deal with the danger first. Then, if it is safe, switch off and unplug, and tell us in Slack.

The full lists: Module 2 — Rules summary.

When something goes wrong

Fire, smoke or an electrical fault: deal with the danger first. If something is burning, warn the people around you, get out and call 112, and use the nearest fire extinguisher only if you can do it safely. Then, if it is safe, switch the dryer off and unplug it, and tell us in Slack straight away.

For everything else, post in the Slack channel #3D-Skrivare. For something urgent, tag @roomdev-3d.

• A run is set to the wrong temperature for your material: wait until it has finished and its owner has collected their spools. Do not change a run in progress.

• Something is wrong with a dryer (it will not switch on, or it does something you did not expect): post in Slack. Do not change the settings of anyone else's run.

Tell us when something breaks. The makerspace would rather teach than punish.

Learn more

• The course: 2.7 Drying filament, and the two dryers, and the AMS pages Bambu Lab AMS 2 Pro and Bambu Lab AMS HT for drying during a print.

• 3D Printing.

• Bambu Lab's guide to drying filament. Nothing from Bambu Lab is required.

Image sources: reference photos, from the manufacturers' pages for the SUNLU FilaDryer S4 and the Royal Catering RCDA-500/15S.