Prateek Jha

INTRODUCTION

The Eggbot was invented by Bruce Shapiro ( http://egg-bot.com/ ) .It is a CNC (Computer Numeric Control) machine that can 'ink' on spherical surfaces . The word egg was attached to his invention because initially he intended to use the machine for designing easter eggs.

Though the machine looks simple , its a heck of a work to find the right parts , materials , control etc. As I took up this project , initially I was quite blank as to how to proceed towards it . Slowly , it started taking shape and until I could come out with something presentable. Below is the VERSION 1 of my design and a video of my machine in action.

I've tried to write " HIT " in rockwell font . As you can see , it misses one horizontal line in the " T " which I'm yet to fix in my code .

As it was for the first time I designed a CNC machine , I had to cross a lot of hurdles before I could realize it.

So let me begin with the various steps I took , obstacles I overcame and the solutions I found.

So , we are to emulate the Eggbot .

The first step is to fully understand how it works .

There are two stepper motors involved.One which rotates the egg ( lets call it the Y-stepper) and the second which positions the pen ( lets call it the X-stepper) . And there is a servo motor which moves the pen up/down (the Z-servo) .

One important thing to note is that the pen falls down upon the egg and follows the curved surface of the egg by its own weight , which is realized with the help of a hinge. I really liked this idea when i understood it for the first time . Simple but yet very powerful .

Then we have the mechanical body and the controller + the motor drivers .

These are the basic parts of the machine . Now lets take each part one by one . Firstly the hardware realization and then the software .

Hardware Realization