What is it?

This is the perfect motion controller for small CNC projects. It runs and supports all the features of the latest version of Grbl firmware. It is designed to be controlled via USB from PC, Mac, Linux, etc. using any standard GCode sender. It also has the added feature of being able to plug into a Raspberry Pi header and use a sender on Raspberry Pi without any external cables.

Note: This kit is for the basic "motherboard" it does not include the stepper drivers or Arduino Nano.

Why did you make it?

I wanted a low cost CNC controller that works with a Raspberry Pi. A Raspberry Pi is powerful, but it does not have the real time capability needed for CNC. The Arduino Nano on this controller provides that.

What makes it special?

The modular design keeps costs down by allowing you to buy the drivers and Nano from high volume retailers. It also allows you to swap the modules into other projects or easily replace broken ones.

All of the Grbl I/O features are brought out to a header connector. Each I/O function also has its own ground pin adjacent to it to make your wiring easier.

• Limit switch pins for each axis.
• Z Probe.
• Control Switches. There are pins for the Feedhold, Cycle Start and Grbl Reset Buttons.
• Spindle. This can be setup for on/off or variable speed (PWM)
• Flood and Mist Coolant.

Stepper Drivers

Grbl is a 3 axis controller. The controller supports those axes and adds an extra "ganged" driver in case you machine has 2 motors on one axis.

Servo Connector

There is a connector for a hobby servo. This is connected to to the Raspberry Pi I/O pin 12. You should only use a small servo because of the limited 5V power that can be provided.

Instructions, Usage, Support and Source Files.

There is a comprehensive blog post the controller here.

FAQ:

• What Axis has the 2 ganged drivers? If you use unmodified Grbl the Y axis would have 2 drivers available for use. It is easy to modify the cpu_map.h to switch that to either the X or Z axis.
• What GCode senders does it support? It works with any GCode sender that support Grbl via USB serial port. Universal GCode Sender, Chilipeppr and bCNC are some of the more popular ones. bCNC works great on Raspberry Pi.
• Where do you buy the stepper drivers? Pololu is a great place to buy them. You can also get them on Amazon, eBay and AliExpress. Search for StepStick or A4988 (the driver chip).
• Where do you buy Arduino Nanos? You can buy direct for Arduino, or buy cheaper clones on Amazon, eBay and AliExpress.
• What type of power supply should be used? With typical stepper drivers, the ideal voltage is between 9V and 24V. Do not go above 28V.
• Wouldn't the design be better if you did X? I don't know what X is, but if you send me a message and I incorporate your idea, I will send you a free version of the new design.