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 this installment, I added a servo to the frame to make the head turn. I did this by mounting it on the cross bar through which the head rod passed. This cross bar was a little higher up than the connection point for the turning mechanism, so I cut a small piece of 2"X3", mounted this to the frame using a couple of screws, and mounted the servo to the wood using hot glue. I wasn't sure if this was going to work, but it seems to.
Before adding the servo, I was a bit concerned that there would be too much friction for a standard servo to drive the motion. It turned out that my concern wasn't entirely without merit. The servo was able to drive it, but there was a minor problem. The music wire I was using as a push rod wasn't really strong enough. Every time the servo pushed on the mechanism, the music wire bent quite a bit before it was able to make the head move. This has me wondering whether too much force is required for the servo to be able to handle it over the long haul.
Another problem I had was that the 1/2" PVC going through the 3/4" "cross" piece of PVC was very loose. When the servo's arm rotated, a portion of the motion was lost in taking up slack in the loose-fitting PVC pieces instead of turning the skull, so the skull turned less than it should have. I need to find a way to make this fitting a little tighter. I have not yet figured out how to do this. More to come...
Turning head mechanism part 3
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Page last modified 09/07/2009