CNC Air Blast Controller

ESP32-based controller for automatic chip clearing on CNC machines using timed compressed-air bursts.

Why This Exists

CNC routers generate a lot of chips and dust that can:

• Obscure the cutting path and workpiece
• Cause poor cut quality when chips re-cut
• Clog up the work area and reduce spindle cooling
• Make it difficult to see what's happening

Traditional solutions (shop vac, flood coolant) are messy, noisy, or impractical for small hobby machines. This controller uses timed compressed air bursts to:

• Clear chips automatically during operation
• Provide precise control over blast timing
• Adjust on-the-fly without stopping your job
• Run silently between bursts (unlike a constant vacuum)

Originally built for a Stepcraft M1000, but applicable to any CNC router, mill, or similar machine with compressed air available.

Features

• Adjustable pulse timing - Configure ON/OFF durations (250-1500ms) for optimal chip clearing
• Menu system - Navigate settings with double-click access:
  • LED brightness control (10-100%)
  • Device info display
• Smart input handling:
  • Single-click to toggle edit mode or select menu items
  • Double-click to enter/exit menu
  • Long-press (≥1s) to pause/resume or exit menu
  • Encoder navigation and adjustment
• Visual feedback:
  • RGB LED status indicator (green=active, blue=editing, red=paused)
  • OLED display shows state and timing values
  • Highlight/inversion shows active selection
• Persistent settings - All configurations saved to ESP32 NVS
• Robust input filtering - Quadrature decoder with illegal transition rejection, button debouncing

Hardware

• MCU: ESP32-WROOM-32 dev board (240MHz dual-core, 4MB flash, 320KB RAM)
• Display: 0.96" OLED SSD1306, 128x64 pixels, I2C
• Input: KY-040 rotary encoder with push button
• LED: WS2812 RGB status indicator
• Output: MOSFET module driving 12V normally-closed solenoid valve
• Safety: Safety input (future integration)

Pin Connections

Component	Pin	ESP32 GPIO	Notes
OLED SDA	SDA	21	I2C data
OLED SCL	SCL	22	I2C clock
Encoder CLK	CLK	25	Quadrature A
Encoder DT	DT	26	Quadrature B
Encoder SW	SW	27	Push button
NeoPixel	DIN	5	WS2812 data
Solenoid	OUT	4	MOSFET gate
Safety Input	IN	17	Future use

All components use 3.3V logic. See HARDWARE_NOTES.md for detailed wiring information, component specifications, and lessons learned.

How It Works

1. Solenoid valve opens/closes a compressed air line on a timed schedule
2. Controller manages pulse timing (ON: 250-1500ms, OFF: 250-1500ms)
3. User interface allows real-time adjustment via rotary encoder and OLED display
4. Settings persist across power cycles using ESP32 non-volatile storage

The modular code structure separates concerns (display, input, output, settings) for easy maintenance and future expansion.

Usage

Main Screen

• Display shows: System state (RUN/IDLE), ON time, OFF time
• Single-click: Toggle between adjusting ON vs OFF time (enters edit mode)
• Rotate encoder (in edit mode): Adjust timing in 250ms steps (250-1500ms range)
• Long-press (≥1s): Pause/resume pulsing
• Double-click: Enter menu
• Edit timeout: Auto-exits edit mode after 5 seconds of inactivity

Menu System

• Double-click: Enter/exit menu
• Rotate encoder: Navigate between menu items
• Single-click: Enter/exit edit mode for selected item
• Long-press (≥1s): Exit menu
• Menu items:
  • LED: Adjust status LED brightness (10-100% in 10% steps)
  • About: View firmware version and device info

LED Status Indicators

• 🟢 Green: Running normally (active, safety OK, spindle running)
• 🔵 Blue: Adjusting parameters (edit mode active)
• 🔴 Red: System paused
• ⚫ Off: Idle or not active

Technical Details

• Encoder handling: Quadrature decoding with 4 transitions per detent, illegal transition rejection
• Button debouncing: Minimum event spacing of 50ms
• Double-click detection: 400ms window
• Long-press threshold: 1000ms
• Edit timeout: 5000ms (main screen only, menu has manual control)
• Display refresh: Hash-based change detection to minimize flicker
• NVS persistence: ON/OFF timing, LED brightness, OLED brightness
• Upload speed: 921600 baud
• Serial monitor: 115200 baud

Future Enhancements

• Spindle input integration (hardware ready on GPIO, software stubbed)
• Timing presets for different materials (wood, metal, plastic)
• Manual pulse trigger for testing
• Pulse counter display and statistics
• Error handling with visual feedback

License

MIT License - See LICENSE file for details

Author

ecpunk
GitHub: github.com/ecpunk/CNC-Air-Blaster