The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • PolyDryer Internal Fan Puzzle

    With the humidity inside the PolyDryer boxes being roughly proportional to the amount of filament on the spool, I printed a slightly modified airlock plate and a TPU seal ring, then stuck a tiny fan on it:

    PolyDryer airlock plate - tiny fan
    PolyDryer airlock plate – tiny fan

    It just barely clears the curved air guide inside:

    PolyDryer airlock plate - tiny fan installed
    PolyDryer airlock plate – tiny fan installed

    The tea bags full of desiccant allow some wind between them and the filament in the spool, but I obviously must re-think that setup. There’s enough clearance for what should be reasonable circulation, so i defined it to be good enough for now.

    The box of TPU started at 25 %RH, dropped to 22 %RH overnight, then returned to 25 %RH the next day:

    PolyDryer TPU - 25 pct RH
    PolyDryer TPU – 25 pct RH

    Now that I’m watching more often, I’ve seen the meter glitch to 10% for a few seconds:

    PolyDryer TPU - 10 pct RH glitch
    PolyDryer TPU – 10 pct RH glitch

    A humidity indicator card suggests the air is under 20 %RH:

    PolyDryer TPU - humidity indicator card
    PolyDryer TPU – humidity indicator card

    It may be the filament can outgas water vapor as rapidly as the desiccant can remove it, but I expected the fan to make at least a little difference.

    I have no idea what’s going on in those boxes.