Affordable CNC Mill Project Overview

Sep 13, 2024

Building a CNC Mill for Under $100

Introduction

  • Project involves building a CNC mill using 3D printed parts and leftover components.
  • Objective: Low-cost CNC capable of cutting aluminum.
  • Initial purchase attempts found commercial options too expensive.

Parts and Design

  • Utilized parts from a personal collection, missing only a spindle, build plate, and bearings.
  • 3D printed parts (in blue) used for structure and housing electronics.
  • Printing parts took three days.

Spindle

  • Used a basic brushed DC motor as a spindle, described as noisy and inaccurate.

Electronics Setup

  • Power Supply: 24V, 20A (excess for needs, but available).
  • Controller: Arduino Uno running GRBL firmware.
    • Arduino max voltage: 20V, used a buck converter to step down to 12V.
    • Removed bulky barrel connector, soldered buck converter output directly.
  • No smoke or explosions after setup.
  • Stepper Drivers: Connected to Arduino with a breakout board.
    • Logic by Arduino, power from 24V.

Spindle Control

  • Created a brush DC speed controller using a 555 timer and MOSFET.
    • Timer set at ~500Hz; duty cycle varies with potentiometer adjustment.
    • Includes protective flyback diode.

Assembly

  • Enclosure for electronics completed.
  • Power Distribution:
    • 24V powers buck converter (12V to Arduino/fan) and main switch.
    • Stepper drivers powered by 24V rail.
    • Second switch powers motor speed controller.
  • Build Plate: Quarter-inch aluminum drilled for mounting.

Firmware and Software

  • Firmware: GRBL (open-source) uploaded to Arduino.
  • Software: Universal G-code Sender for control.
  • Initial tests (movement, hole pattern): Successful.

Testing and Projects

  • Used Easel for design; started with low-value material (wood).
  • Pine wood test: Satisfactory, stringy edges due to material.
  • Oak test: Cleaner results.
  • Applied wood stain and polyurethane for finish.

Cutting Metal

  • Attempted aluminum cutting with 6061 sheet.
    • Spindle: 2 flute, 1" end mill, 18,000 RPM.
    • Noted a lack of rigidity causing poor cuts.
    • Issues: Backlash, thin rails, vibrations.
    • Possible improvements: Thicker rails or linear rails.

Conclusion

  • Despite limitations, the CNC mill successfully cuts materials.
  • Total cost: $74.92 (spindle, build plate, bearings, end mills purchased).
  • Future plans for improvements and additional videos.