LEGO CNC EggBot

For easter we built an EggBot with LEGO™ Technic parts, 28BYJ-48 stepper motors, and a GRBL-based CNC controller!

This is a fun family project that also lets you get experience building and using a real CNC machine with the same electronics and software you can use for other CNC machines!

Largely inspired by this Hackaday article

Parts:
* 6pc M3x10 bolts and nuts to attach the steppers to the LEGO mounts
* A bunch of LEGOs (including Technic ones)

Setting up the hardware:
* Based on the controller board you purchase, you may also need to tune the stepper current. Usually this involves turning a small potentiometer screw on the board until the steppers just begin to move smoothly. Look at the instructions for the driver board you purchase.

Running the software:
* If your controller board comes pre-configured with GRBL you probably don't need to modify the firmware at all. Otherwise, flash the board with a version of GRBL according to the instructions for your controller.

Configuring GRBL
* See the Hackaday article for well written details on how to configure steps/mm settings in GRBL

Creating designs:
* Open the SVG in Inskcape
* Create a new layer, right click your design and select "Move to Layer" and move the SVG path to the new layer
* Select “Extensions…Gcodetools…Orientation points”, hit apply and close
* Select “Extensions…Gcodetools…Tools library”, choose cylinder, hit apply and close
* In the gray tool settings box on the canvas, adjust the box to 40000 feed rate and 400 plunge rate
* Select the path
* Select “Extensions…Gcodetools…Path to Gcode” and use "Pass by Pass" to not have duplicate paths. Hit apply
* Open the saved Gcode file in CNCjs
* Physically adjust your EggBot so that it's at a sensible 0,0,0 position for your Egg (pen is at 'bottom' of the egg, and the pen is resting lightly on the egg). Zero out all the axes in CNCjs
* Hit the play button in CNCjs!