Originally, I thought that combining a SONOFF TH Elite with a PTC heater and a fan, plus a simple temperature and humidity control setup, would be enough to easily build a smart filament drying box. But after more than a week of continuous experiments and adjustments, I realized I had seriously underestimated the complexity of making it truly work. Maybe I need to spend even more time validating ideas and iterating designs before I can eventually create a smart drying box that I’m truly satisfied with.
To gain some reference, I also purchased a commercial product: the Bambu Lab AMS HT filament feeder box with integrated drying functionality. It arrived today. I’m looking forward to studying its internal structure and design logic.
I performed a three-hour drying function test using the Bambu Lab AMS HT, placing a spool of PLA filament inside. Since PLA requires relatively lower drying temperatures, I set the system to target 55°C. After a while, the internal environment stabilized.
At that point, the AMS TH display showed a temperature of 58°C. However, the SNZB-02D temperature and humidity sensor I placed above the filament spool reported only about 49°C. This indicates that even in a commercial, factory-designed drying box, there’s still a noticeable temperature gradient inside the enclosure – and precise uniformity is difficult to achieve.
Additionally, I noticed that even during active drying, the AMS TH does not rotate the filament spool using any motorized mechanism to promote even heating or airflow around the material. It relies purely on ambient temperature rise created by the internal heating module.
Also, during unboxing, the AMS TH prompted me to place a small pack of desiccant underneath the filament rotation axle. The designated space for desiccant is very limited, and the quantity provided is just a small sachet. This suggests that even in professional designs, massive amounts of desiccant are not considered necessary.
For my future custom dry box design, this observation gives me confidence – I won’t need to reserve a huge volume for desiccant either and can focus more on active temperature and airflow control.
Due to time constraints, I haven’t yet conducted further tests on different filament types or temperature settings. I plan to continue collecting more data over time,
and eventually consolidate everything into a dedicated experimental report in a future blog post.
For now, the more immediate issue is that adding the AMS TH into my setup has made my workspace considerably more cluttered. Before diving deeper into experiments, I need to reorganize my workbench and find a cleaner, more efficient way to integrate the new hardware.
Currently, my 3D printer setup connects to three separate AMS units:
an original AMS, an AMS 2 Pro, and the newly added AMS HT. They are scattered around the printer—one above, and two on either side – causing the back area of the printer to be crowded with tangled cables and filament tubes. Even though everything technically works, the mess is really triggering my sense of order.
To solve this, I’m planning to design and build a custom rack to unify all three AMS units into a single, clean structure. This should not only make the whole setup more visually tidy but also improve maintenance and future expansion.
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