Read the documentation on https://github.com/gnea/grbl/wiki for a better understanding. Feel free to also use ChatGPT to clear up any unclear sections regarding GRBL, wiring, etc.
Install the latest Arduino IDE (2.x) from the official Arduino website: https://www.arduino.cc/en/software
Install and import the modified GRBL library (from https://github.com/ruizivo/GRBL-28byj-48-Servo/tree/1d0d05261973064152ef94c29ec2d0c7e0b3aace) using the following docs as a guide on how to import it into Arduino 2.x: https://github.com/gnea/grbl/wiki/Compiling-Grbl#if-you-are-using-arduino-ide-2x
Note: Here, instead of download the GRBL source code, download the modified GRBL from here https://github.com/ruizivo/GRBL-28byj-48-Servo/tree/1d0d05261973064152ef94c29ec2d0c7e0b3aace.
We must use the June 12, 2016 commit version (as the latest version has compilation errors).
We use the modified GRBL library as it supports the BYJ48 stepper motors directly.
Once the Arduino board is correctly selected and you run grblUpload, go to Tools>Serial Monitor and select 115200 baud (re-run if needed).
You should then see a message such as in the serial monitor: Grbl 0.9j ['$' for help]
This indicates that the grbl was successfully installed!
You can read about GRBL wiring on the following docs: https://github.com/gnea/grbl/wiki/Connecting-Grbl#grbls-pins. We use the modified GRBL, which already defines which pins to connect our stepper motor drivers and servo to, as defined in the table below.
Wiring Configuration Diagram
First, connect the stepper motors to the stepper motor drivers (there is only one possible direction to plug in).
Then, connect devices as follows:
| Device | Pin |
|---|---|
| Servo (Yellow Wire) | D11 |
| X-Axis Stepper Driver (IN1-IN4) | Pins D2-D5 |
| Y-Axis Stepper Driver (IN1-IN4) | Pins A0-A3 |
We will also include limit switches. Limit switches allow our CNC machine to emergency stop when we reach the end our our axle. There are two configuration options, NC (normally closed) and NO (normally open). We go with the typical NC, which is safer as if there is a wire problem then the circuit will be open (thus will send an alarm signal).
| Device | NC (lever sticking up end) | COM (lever down end) |
|---|---|---|
| X-Axis Limit | D9 | GND |
| Y-Axis Limit | D10 | GND |
Finally, connect the power and ground cables as shown in the Wiring Configuration diagram above (the steppers and servos are also correctly shown):
Use the Universal Gcode sender application, to connect and control your CNC machine (this can also be done via the Serial Monitor in your Arduino IDE). You can also use it to send a gcode image to your hardware device: https://github.com/winder/Universal-G-Code-Sender
Download and Install the latest Platform version.
💡 Note on MacOS, after double-clicking the .dmg file you will not get any pop-up/installation tips. Instead, check your finder sidebar, and you will see the mounted disk “Universal G-Code Platform”. Click here, then drag and drop the “Universal G-Code Platform” into your applications folder and then launch.
Then, connect to your device by specifying as below (and the correct port)
Once connected, you should see something like this:
On the bottom left, you can use the jog controller to control your axis. If everything is wired correctly, then you can use this to move your Y and X axis controllers manually.
Since homing does not work, you can use this to manually “reset” your CNC to the start position before you start drawing.
With everything wired up correctly and GRBL running on your Arduino, we will now set-up the servo (so that it can move the pen up and down).
To control the servo through the GRBL (/Arduino Serial monitor Terminal), you can send the following commands:
- Command
M03 Sxxx(xxx between 0 and 255) to rotate the servo between 0-90. - Command
M05to turn the servo to zero degrees.
If none of these work commands work, make sure to double-check your wiring to see that the servo works. In the worst case, trying running an Arduino example file for controlling the servo to verify it works correctly.
For our set-up, do as follows:
-
Set the servo to degree 0 using
M05orM03 Sxxx. Then, connect the white servo lever, pointed upwards at 45 degree angle
-
Now, when you move to degree 85 (
M03 S225), it should go downwards allowing the pen to touch the paper
We have included limit switches so that it performs a hard-stop when your CNC machine is about to hit the corner. Make sure you have wired your limit switches as explained above.
Then, within Arduino Serial Monitor or UGS Platform Console (connecting to your Arduino running GRBL), you can send the following command:
Type $ into the terminal to the connected 2D Plotter
$21=1 → Enable hard limits (so the CNC machine stops if hitting a switch)
$$ → To verify it is correctly saved
If wired correctly, you should see the following error when hitting a limit switch in Universal G-Code Sender
If you get an alarm, then it means a limit switch was triggered. To clear the alarm:
- Use command
$X(sometimes you’ll have to disconnect then reconnect, then send the$Xcommand). - Then, jog the controller so that the the limit switch is released (i.e. move away from the axis.
- Repeat steps 1 & 2 if the alarm triggered again when the switch was released.
Follow instructions from here: https://youtu.be/d8ZynbxfBDo?feature=shared&t=658
Download and install Inkscape v0.48.5 (https://inkscape.org/release/inkscape-0.48.5/windows/32-bit/exe/dl/). Newer versions don’t support the plugin that we use to convert the image to gcode (and control the servo).
❗ A Windows computer is required for this specific version of InkScape (as the latest MacOS doesn’t support this old version of InkScape).Then install and add the extension to InkScape (from the video). We need this extension as it tells UGS when to bring the pen up and down. Continue the video tutorial for generating your own Gcode.
You can go check the “/Software” folder of this Github Repository to see some of the gcode files we generated (includes a square, a cat, a smaller cat and a “Making Intelligent Things” text.
Once you have wired everything correctly, verified via the GCode Platform jog controller that the steppers and servo are working correctly, then you are ready to draw some images!
In Universal Gcode Platform:
- Use the jog controller to bring your pen to the starting corner (test and identify where this is)
- File>Open a Gcode file
- Click on “Send” (or Program>Send) and watch the machine print!
Trouble shoot as necessary afterwards (e.g. re-adjusting belt, …).
Here are some photos of our final project:
