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Re: Building fully flexible tail (several joints) with minimal actuation required
Mechanicalbrain, I think I actually had a toy snake sort of like that at one time or another. But it wasn't actuated, you just held it out and tilted it a little and gravity would make it move. It was a lot like plastic roller chain actually.
Anyway, I tried to make a model this thing with a piece of roller chain (#35) and a rubber band (#33) cut so it would be straight and not in a loop. I tied it to two points on the chain such that when the chain was straight, the rubber band would be under tension. I then tied a piece of string to the end of the chain, and ran it down the other side. I then placed a small zip tie at every link to keep the string and the rubber band close to the chain. Anyway, the results were quite marginal at best. Some links would want to move and some would want to stay. The biggest trend I noticed is that some links would want to move in the opposite direction from the direction the chain was moving as a whole. This resulted in the chain pivoting at only one or two points out of maybe 12. Basically, the chain was attempting to stack on itself every time the string was pulled. For the tail to properly curl (in one direction) I would need to have stops on each "link" so that it could not pivot in what we'll call the negative direction (the other way past being straight). And even then, I'm still not sure it would work, but I think there'd be much better chances.
What I want it to be able to do is go from being straight, to being sort of like this  but on it's side.
And now here's the really hard part. This thing's motion has to look good on TV (slow and smooth) and it will be all covered in flowers. There mustn't be anything visible except for flowers (I believe carnations to be exact) so it will need some sort of flexible skin/covering.
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Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
Last edited by sanddrag : 27-09-2005 at 22:07.
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