The 5L sealed container I’ve been using is typically intended for filament isolation and storage. By placing a filament roller base inside and adding a PTFE feed-through on the lid, it can double as a sealed filament dry box—usable directly during printing. My goal is to eventually turn the filament dryer I’m building into a dual-purpose setup – not just for drying, but also for long-term storage and direct printing usage. That means I needed to add a filament roller inside the drying container.
To simplify the fabrication process and avoid unnecessary parts, I didn’t want to rely on separate ball bearings or screws. Instead, I found a clever design online that uses a planetary gear-style roller – Planetary Gear-Style Filament Stand. I gave it a try, and the result was surprisingly smooth – no bearings needed!
After printing the roller base, I did a quick dry fit to check the internal layout.
I realized that with the current PTC module and fan, the combined volume was too large to fit alongside the roller and filament spool inside the small container – even if I mounted the TH Elite controller externally. This made me reconsider the aluminum-encased ceramic heating plate I tested earlier—the one rated at 220V/70°C. While it didn’t reach high enough temperatures in the last test, I suspect the issue might be underpowered output from using only one plate. If I run four or more plates in parallel, the combined heat might be enough to meet the drying requirements.
To validate this idea, I placed another order for a batch of ceramic heating plates.
Once they arrive, I’ll test whether this compact multi-heater approach can deliver better thermal performance in limited space.
One potential advantage of using the aluminum-encased ceramic heater is its rated maximum temperature of 70°C. If that number refers to the actual surface temperature of the aluminum housing, then in theory, I could 3D-print a mounting bracket using materials with a heat deflection temperature above 70°C and mount it directly – safely.
Of course, this assumption is based purely on the product description from the seller. To be sure, I’ll run an experiment to measure the actual surface temperature under real operating conditions.
To verify the surface temperature of the ceramic heater, I used a SONOFF SNZB-02LD sensor. This device features a wired external DS18B20 temperature probe with a metal casing, and supports temperature readings up to 120°C, making it ideal for this test. I attached the metal probe directly to the aluminum housing of the heater, allowing for real-time and precise monitoring of surface temperature. Although the SNZB-02LD supports Zigbee wireless connectivity, it also comes with a built-in display, which was enough for this standalone test. So for simplicity, I didn’t pair it with any hub or automation system – I just read the values directly from the screen.
The result showed that without any cooling fan, the aluminum surface of the heater could reach up to 75°C. However, when a fan was added to help dissipate heat, the temperature stabilized around 55°C. This means that if I use high-temperature 3D printing materials for the mounting bracket, it should be perfectly safe – even under direct contact – without worrying about softening or deformation.
To further improve airflow through the desiccant packs inside the sealed box,
I realized that my current fan was both too bulky and poorly aligned with the airflow direction I needed. So I went online to look for alternatives. Eventually, I came across a compact 30mm × 30mm × 10mm centrifugal blower fan, which pulls air in from the top and pushes it out from the side – perfect for creating horizontal airflow. Even better, it only cost me ￥8.8 RMB (shipping included)—just a little over €1 Euro. That’s literally cheaper than a bottle of Coke in Germany! I can’t wait for it to arrive so I can put it to the test.
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