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Every other week, MAKE's awesome interns tell about the projects they're building in the Make: Labs, the trouble they've gotten into, and what they'll make next.

By Kris Magri, engineering intern

How I designed Makey, Part III: The Ping sonar rangefinder and maiden voyage

As we return to our robot design saga, making Makey the Robot for MAKE, Volume 19 ...

The actual robot is still just a prototype with 2 wheels and motors and no sensors, electronics, or brains inside. The better body exists only in the computer. Maker Faire is looming. I've been tapped to give two "Make Your Own Robot" workshops, and I reckon that having a working robot would be a very good idea.

I'm trying to get the Arduino into the robot body. Suddenly I learn a profound lesson regarding computer-aided design. In real life, circuit boards cannot morph through walls into their desired resting place. In the computer, it happens all the time. With a simple motion of the mouse, the Arduino circuit board has glided into place, right through the aluminum robot body ... but in real life, it won't fit. There is no possible angle or tilt that will get the Arduino into the robot. Out come the Vise-Grips and hacksaw. I saw, bend, and twist off the offending aluminum tabs. This is reality-aided design.

The battery pack doesn't fit because it hits the nuts and bolts that hold the motors in. It fit just fine in the computer model, since I didn't bother including the nuts and bolts. I'm ready to toss the computer out the window.

I show up at the Make: Labs with my fail robot. Our crew has been working like demons for weeks getting ready for Maker Faire -- preparing demos, packing everything under the sun, buying materials -- the lab is a madhouse. Eric, myself, and Steven are practically tripping over each other. I'm frantic to get the Arduino into the body and get the sonar sensor mounted somehow. Eric suggests double-stick tape. I refuse. Tape and glue, I assert, are for people who don't know about bolts and rivets. Eric manages to cram the Arduino in sideways. It barely fits, actually, it doesn't quite fit, it sticks up a little. When I drill a mounting hole, 1/3 of the hole isn't there. But the bolt manages to hold.

At this point I only have a vague idea of what motor will be turning Makey's "eyes" or how to fit it inside. We zoom off to the local hobby shop and pay way too much for the smallest servomotor they have in stock.

Steven offers to take on the servomotor/sonar sensor mounting problem. He's making detailed measurements and calculations, trying to figure out how much space there is and where the servomotor will fit into this 3D space without hitting the electronics. He marks everything and explains his calculations to me. I can't follow them, but it sounds good and looks like it might just fit. I drill the holes, we put the servo in, then close up the robot. It fits! There is much rejoicing.

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From MAKE magazine:

In MAKE, Volume 19: Robots, Rovers, and Drones, learn how to make a model plane with an autopilot and a built-in robot brain. We'll also show you how to make a comfortable chair and footstool out of a single sheet of plywood, a bicyclist's vest that shows how fast you're going, and projects that introduce you to servomotors. All this, and lots more, in MAKE, Volume 19! Subscribe here. Buy the issue in the Maker Shed.

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