Dankdryer

ESP32, OpenSCAD, and KiCad sources for the Dankdryer, the world's best filament dryer. a nick black joint

Features

• Temperatures up to at least 150℃ when printed with proper materials.
  • Such temperatures are appropriate (necessary) for certain engineering filaments.
  • A high-temperature spool is required at these temperatures.
• Accurate weight sensing throughout to determine how much water has been exorcised.
  • Post contextless deltas to reddit in the heat of dumbass arguments! DATA, bitch!
• Slow rotation like delicious savory meat.
• Equal heating of all the spool's filament.
• Control and reporting over MQTT via WiFi.
• OTA firmware upgrades.
• Isolated hot and cool chambers, with most active equipment in the cool chamber.
• Humidity sensing and temperature sensing in both chambers.
• Entirely open source.

More info at dankwiki.

Dependencies

The project is built with GNU Make. Running make in the toplevel will attempt to build firmware and STLs. Building the firmware requires the esp-idf library and a configured ESP-IDF environment (i.e. the various IDF_* environment variables must be set), along with CMake. idf.py ought be in your $PATH, and work when invoked.

Firmware

• esp-idf 5.3+
• CMake 3.16+

3D models

• OpenSCAD 2024.10+

I use BOSL2, which is included as a submodule.

PCB

• KiCad 8+

Construction / BOM

The device as designed requires approximately 600g of high-temperature filament (PA6-CF, PA6-GF, PAHT-CF, etc.) to print. The exact amount of filament will depend on material and print settings. Six pieces must be printed:

• Hot chamber
• Cool chamber
• Top
• Motor sheath
• Sheath coupling
• Spool platform

The hot and cool chamber dominate filament consumption, though the top is non-negligible.

Hot chamber

• 230C 110V ceramic heating element
• KSD301 175C NC thermal control
• Hall sensor
• Custom PCB (fabrication cost is negligible; see components below)

We need a temperature sensor and hall effect sensor (and obviously the heating circuit) in the hot box; nothing else ought be there.

Cool chamber

• Greartisan 5RPM 12V DC motor
• NEMA plug + rocker switch
• 160W 12V AC adapter
• 8dBi antenna
• 5kg bar strain load cell
• 2-to-4 cable splitter
• Custom PCB (fabrication cost is negligible; see components below)

PCB components

Generated via Kicad:

MQTT

MQTT is used to report status and to accept commands.

Controls

• NAME/control/tare: tare using the last weight read
• NAME/control/dry: takes as argument a string "DRYS/TEMP", where DRYS and TEMP are unsigned integers specifying the number of seconds to dry, and the temperature to dry at. Any ongoing drying operation will be replaced with the newly specified one. Specifying zero for DRYS will cancel any ongoing drying operation.
• NAME/control/lpwm: takes as argument a hexadecimal number between 0 and 255, left-padded with zeroes so as to be exactly two digits, i.e. "00".."ff". Sets the lower fan's PWM.
• NAME/control/upwm: takes as argument a hexadecimal number between 0 and 255, left-padded with zeroes so as to be exactly two digits, i.e. "00".."ff". Sets the upper fan's PWM.
• NAME/control/factoryreset: takes no arguments. Blanks the persistent storage, disables the motor and heater, and reboots.

Renderings

View from the top of the lower chamber by itself, with the AC adapter and motor assembly present.

Combined OpenSCAD render for mating testing.

Questions

• How does air flow? Let's get some visible air and test it.
• What all could we accomplish by reading RFID?