Quick start CNC shield v3 for Arduino

Posted by Marius Cloete on

In this guide I will help you get started with the CNC shield listed on our website and using the UNO board.

Loading the Software:

Start by Downloading the following….

With the XLoader change the settings as follows:

  • Select the HEX file you would like to Upload. 
  • Make sure to select the correct Arduino Board Setup.
  • Select the correct COM Port.
  • Keep the Baud Rate as is… (It will change for each board type.)

Click on the Upload to send the HEX file to your board.

You will see the "TX" and "RX" LEDs flashing while uploading.



 Slide your CNC shield onto your UNO board making sure the pins are flush.


Next add the A4988 Drivers.

On the back of the Drivers you will see the PIN identification. The enable pin must match the EN pin on the shield.


 Now you can fit the heat sinks.


If you do have two step motors on one axis then you can set the jumper to duplicate the selected axis.

The following jumper setting is set to copy the Y axis on the 4th driver.

Other Pins:

  • Limit Switch Pins have been doubled up so that each axis has a “Top/+” and “Bottom/-“. This makes it easier to install two limit switches for each axis. (For use with a normally open switch)
  • EStop – These pins can be connected  to an emergency stop switch. This does the same as the RESET button on the Arduino board. (We do advice that an extra emergency button also be installed that cuts power to all machinery. A REAL EMERGENCY BUTTON)
  • Spindle and coolant control has their own pins.
  • External GRBL Command Pins have been broken out allowing you to add buttons


Now you can connect the stepper motors:


  Finally connect the external 12 volt power supply:


The Arduino CNC Shield supports power supplies up to 36V. That does not mean that all Pololu Stepper drivers can run that high. A4988 drivers are not designed to run at 36V and will blow up the first time you power them up at that voltage. The 36V are for drivers like the Pololu DRV8825 that can run on +36V.


Additional Software:

To send commands to your CNC board you will need a g-code sender.

Download the Universal-G-Code-Sender.

Once downloaded, connect the UNO boards usb to your computer and take note of the COM port it is connected to.

Run the start-windows.bat or the JAR file directly.

You will be presented with the following screen:



 Select your COM port and the Baud rate and click "Open".

Once connected you can enable the "Arrow key movement"  and test the stepper motors.

For more information please visit

Also see

see part two for more info


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