Dankdryer improvements

In an earlier article, I designed and constructed a high-temperature filament dryer. Before I was even done putting together the first design, I was thinking of improvements for reliability, efficiency, cost, and ease of assembly. I've put some of them into effect, and the results are most pleasing.

Models

Rather than mounting the RC522 directly onto the bottom of the top chamber, we print a short mount for it (building the mount into the hotbox would make it very difficult to print). This reduces the heat directly transferred to the RC522, without adding new connectors. We add the necessary screw holes into the bottom of the chamber.

I changed the motor mount from a rectangular to a trapezoidal prism, and then cut an inverted trapezoidal prism out from its center, reducing material costs for the cool chamber. I raised the air shield to cover the entirety of the load cell.

I moved from a worm drive to a more efficient hypoid gear. This reduced the choppiness of the platter rotation.

Electronics

Let's toss the TB6612FNG motor controller. We only need one direction of rotation, so we control the motor with an RFP30N06LE N-channel MOSFET, a 1N5817 Schottky diode, and a 10K resistor. The n-FET goes on the ground side of the motor, and the diode runs in parallel with the load (i.e. is connected to the motor's two pins). The resistor pulls down the gate lead. This eliminates four net (AIN1, AIN2, STBY, AO2, APWM go away; we add GATE) wires while adding one resistor, a net reduction of seven joints. I'm not certain that it's actually any cheaper, though; it might actually be more expensive.