In part 1, I built a frame out of PVC, on which I mounted a Bucky skull. The frame included a mechanism to make the head turn. In part 2, I added a servo to the frame to make the head turn. I wasn't very happy with the quality of movement from the servo. I don't think it was powerful enough to drive the head, so I decided to switch gears (somewhat literally). Instead, I put a conventional motor on the mechanism. This motor is more powerful than the servo, so it is able to drive the mechanism easily. The motor I used is the same one I used on the leering prop. The drawback to using the motor over the servo is that I don't have much control over the motor. I did include a motor control circuit so that I could turn the motor on and off, but that is it. That will at least give me a little control, so the motion won't look quite so regular.
Surprisingly, I didn't need a very long crank arm for this mechanism. It was only about 2 inches long. I made it out of 1/8" thick by 3/4" wide aluminum. I drilled a 1/4" hole on one end of the arm for the motor shaft. On the other end, I drilled a hole big enough for a piece of wire coat hanger, which is what I used to connect the two arms of the mechanism. Then I bent the crank arm by putting it in my vise and taking a hammer to it until it was angled enough so that the coat hanger wouldn't hit the motor shaft on the backswing of the rotation.
One adjustment I made to remove some of the slop in the head-turning mechanism was to drill a hole (3/4", I believe, but I'm not sure) in a 1" PVC end cap that was big enough for the 1/2" pipe to pass through. I then put this cap on top of the lower 3/4" cross piece that the 1/2" pipe is running through. See the pictures below to see what I'm talking about.
I also created a video of it in operation, including the prop I ultimately turned it into. To conserve space/bandwidth, I used DivX, so your computer must have that in order to play the video. If it doesn't play right (or at all) for you, that's probably the problem. The video is 12MB and is 2 minutes.
Page last modified 09/08/2009