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10. Mechanical Design, machine Design

Drawing CNC machine

Hero Shot

Assignements requirements

group assignment

  • design a machine that includes mechanism+actuation+automation+application
  • build the mechanical parts and operate it manually
  • document the group project and your individual contribution

Step 1: Gather Components

You will need the following components:

  • Arduino board: Typically an Arduino Uno.
  • CNC shield: A shield that fits on the Arduino and allows for easy connection of stepper motor drivers.
  • Stepper motors: NEMA 17 or NEMA 23 motors are common choices.
  • Stepper motor drivers: A4988 or DRV8825 drivers.
  • Power supply: A power supply that matches the voltage and current requirements of your motors and drivers.
  • Frame: Aluminum profiles, wood, or any sturdy material for the frame.
  • Linear motion components: Bearings, lead screws, or belts and pulleys.
  • End stops or limit switches: To define the working area limits.
  • Spindle or tool: For a CNC router, you’ll need a spindle or Dremel tool.
  • Wires and connectors: For electrical connections.
  • Miscellaneous: Screws, nuts, bolts, and other hardware.

Step 2: Detailed Wiring

  1. Connect the Motors to the Drivers:

    • Y-Axis Motors:

      • For two Y-axis motors, you will likely run them in parallel or use two separate drivers.
      • If using separate drivers, connect each Y-axis motor to its own driver on the CNC shield.
      • Ensure the correct wiring sequence (A+, A-, B+, B-) from the motor to the driver.

    • X-Axis and Z-Axis Motors:

      • Connect the X-axis motor to its respective driver on the CNC shield.
      • Connect the Z-axis motor to its driver on the CNC shield.

  2. Connect the Power Supply:

    • Connect the power supply to the CNC shield. Ensure the voltage matches the requirements of your stepper motor drivers (typically 12V or 24V).
    • Positive (red wire) goes to the VCC terminal and negative (black wire) goes to the GND terminal.

  3. Connect End Stops or Limit Switches:

    • Attach end stops or limit switches at the ends of the X, Y, and Z axes.
    • Connect the switches to the corresponding pins on the CNC shield (usually labeled X-min, Y-min, Z-min, etc.).
    • Configure them as normally open (NO) or normally closed (NC) based on your preference and GRBL settings.

  4. Connect the Pen Holder (Z-Axis):

    • Wire the stepper motor for the Z-axis to the corresponding driver on the CNC shield.
    • If using a servo for pen lifting, connect the servo control wire to an available PWM pin on the CNC shield and power it accordingly.

Step 3: Software and Calibration

  1. Install Arduino IDE:

  2. Install GRBL Firmware:

    • Download the GRBL firmware from the GRBL GitHub repository.
    • Open the Arduino IDE, go to Sketch > Include Library > Add .ZIP Library, and select the GRBL .zip file you downloaded.
    • Open the GRBL example sketch by going to File > Examples > grbl > grblUpload.
    • Connect your Arduino to your computer via USB, select the correct board and port under Tools, and upload the sketch.

  3. Install G-Code Sender Software:

    • Download and install Universal G-code Sender (UGS) from UGS Platform.
    • Connect to your Arduino by selecting the correct COM port and baud rate (usually 115200).

Step 4: Calibration

  1. Calibrate Steps per Millimeter:

    • Open UGS and connect to your Arduino.
    • Use the console to enter $$ to display current GRBL settings.
    • Adjust steps per millimeter settings ($100, $101, $102 for X, Y, Z respectively) using the command $100=value, where value is calculated based on your lead screw pitch or belt/pulley ratio.
    • Measure the actual movement and adjust until the movement matches the expected distance.

  2. Set End Stops and Homing:

    • Enable hard limits with $21=1 (to enable limit switches).
    • Enable homing cycle with $22=1.
    • Adjust homing direction and speed settings ($23, $24, $25) as needed for your machine.

Step 5: Running Your First Drawing

  1. Prepare a G-Code File:

    • Use software like Inkscape with the Gcodetools plugin to convert your drawing into G-code.
    • Open Inkscape, create or import your drawing.
    • Use the Gcodetools extension to generate the G-code. Save the file with a .gcode extension.

  2. Load the G-Code File:

    • Open UGS and connect to your Arduino.
    • Load your G-code file by clicking File > Open and selecting your .gcode file.

  3. Secure the Drawing Medium and Set Zero Position:

    • Place the paper or drawing surface on the machine bed and secure it.
    • Manually move the pen holder to the starting position (usually the bottom-left corner of the drawing area).
    • Set this position as the zero point by clicking Reset Zero in UGS.

  4. Start the Drawing:

    • Begin the drawing by clicking Send in UGS.
    • Monitor the machine to ensure it runs smoothly and the pen accurately follows the G-code path.

Additional Tips

  • Fine-tuning: Adjust pen pressure and Z-axis movement to ensure clean lines without damaging the paper.
  • Software Settings: Configure your G-code generator settings to match the dimensions and capabilities of your machine.
  • Troubleshooting: If the machine doesn’t move correctly, recheck wiring and GRBL settings.

By following these detailed steps, you should be able to build and operate your Arduino-based drawing machine with two Y-axes, one X-axis, and a Z-axis for the pen holder. Happy building!

Last update: July 2, 2024