I quickly realized that I was going to have to create a chassis for Junkbot. In the last Junkbot post, I described my first foray into learning to program microcontrollers such as the Atmel Atmega 8. I found the little processor was extremely capable of making LEDs blink. I had also learned enough AVR GCC to blink the LEDs at different rates. 20hz, 10hz, 1hz, etc... All very boring.
Since robot crafting is about more than just making things blink, I decided to move away from the electronics for a little bit and concentrate on the metal portions of the bot. First, I needed a platform to attach all the junk that Junkbot would be made of. The platform needed to support a camera, a couple of battery packs, two servos with wheels and a circuit board that contained the brains. Believe it or not, I found that an old license plate worked perfectly.
License plates are made of a soft metal alloy which is very easy to bend and drill. Since I had literally no experience in metal working, I decided to modify my old license plate as little as possible. I decided to cut the plate nearly in half and bend the sides down. You can see how it turned out.
The bent down sides allowed me to mount the servos on either side of the bot and a caster toward the back. Junkbot's motion would be a simple matter of driving the servos in the same direction for forward and backward and in opposite directions to turn. As I was to find out, however, this is a great configuration for slow moving vehicles that stop to turn, but not so great for little robots that want to go fast.
With the servos and caster mounted, I needed to come up with a way to mount the circuit board that would eventually be Junkbot's brains. You can see in the picture above that four small bolts with nylon washers turned out to be a perfect way to create mounting posts for the circuit board. All of the mounting hardware was purchased at Home Depot for less than $5.
With the chassis for Junkbot mostly complete, I turned my attention to the controller (pictured at the top of this article). I wanted it to have a 'junky' feel also, so back to Home Depot I went. I found some aluminum sheets for sale and picked one up for ~$10. From what I've seen on television, aluminum can be a notoriously difficult metal to deal with. I actually didn't have too much trouble building the case for the controller. I stuck to the basics and didn't attempt any brazing or welding. Fastening the controller case with bolts also gave it a good retro feel.
Bending the aluminum turned out to be an easy exercise. Measure twice and put the metal in a vice. Bend as needed. I used a pair of tin snips and a dremmel tool to cut out the hole for the LCD screen. All and all, I had a good time building the chassis and controller, though, next time I think I'm going to start picking the brains of folks who have experience with this stuff.
Now that I had created a mobile home for an electronic brain and something to control it with, I needed to build the brain. For me, this is the fun part. I love small electronic builds like this. Sure, it's super difficult to debug a microcontroller without expensive equipment but if you're interested in this kind of stuff, the payoff is well worth it. The feeling is fantastic when you get a piece of the bot working after hours and hours of debugging. I've been known to hunker down into a few 12 hour sessions myself. The next Junkbot post will deal with Junkbot's brain.
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