Re: Building fully flexible tail (several joints) with minimal actuation required
 

You haven't mentioned the total length of the tail yet. 8 to 10 ' is what I envision. Close? Now would be a good time to get a estimate of the weight of the flowers. If the entire tail is articulated, then you maybe running into some structural issues. If the strength - weight becomes an issue you could make say the first 4' ridged and the last part of the tail articulated. A 10' articulated tail may exceed the limits of plywood unless you help it.

Re: Building fully flexible tail (several joints) with minimal actuation required
 

Well, we built the tail. It's not quite done yet but it's getting there. It is six links total and made from 2x2" by 3/16 or 1/4" wall steel box tubing and it has UHMW in every joint to help it move freely. Even with it all the way assembled (10-11' out there) it moves very freely at the first joint. I think it can definitely take another 100lbs on it without a problem.

I'll try to get some pics soon.

So, right now, we have a beautiful freely moving set of joined links. In fact, they move a bit too freely. Somewhere something went wrong so that they don't stop rotating at 15 degrees at each joint like they were supposed to. Some links will move a full 90 degrees in relation to the other one. So, we need stops. But rather than building in a hard stop (because welding on/around greased metal is not good), I was wondering if I could put stops on the cable instead. It is 1/4" aircraft cable that runs through loops all along the tail. And I was thinking maybe I could put a cable clamp at the correct position on the cable so that when the cable is pulled, the clamp hits the loop, and then that segment of cable cannot move anymore, and then the segment of cable on the next link will will move until it's stop hits that loop, and so on. Do you think it will work?

Also, right now we plan to have another cable running down the other side with a garage door spring at the end to provide the counter force to bring the tail back to nearly straight. Does that sound okay?

Re: Building fully flexible tail (several joints) with minimal actuation required
 

That sounds like it should work just fine. Be advised that the mechanical stops need to take some pretty big forces if the tail is moving fast. Try to think that you might have a windy day and what that might do to the tail. You don't need to weld in mechanical stops, you can clamp something onto the tubing. You might also be able to attach cables internal to the tail diagonally across the joints. (from left to right) These would be slack until the joint reaches the angle you want and then go taut to stop motion.

Re: Building fully flexible tail (several joints) with minimal actuation required
 

Well, it's almost done. The limiting cables are in and the acuation cables are in and the cylinder is mounted and hooked up. We just have some tweaking to do, like keeping good tension on the actuation cables for well controlled movement. We did a cable along each side and the cylinder is affixed to a lever arm such that when one cable is pulled, the other is released. (a lot of the above stuff isn't shows in the pic). No springs currently but we may need to add some somewhere. Once we get it all dialed in, it looks like it will work just fine.

Anyway, sorry it took so long to get a pic up. Been coming home very late from working on the float. Well, without further delay, here it is :)

Re: Building fully flexible tail (several joints) with minimal actuation required
 

Try to see if you can get a good video up, either of it almost done, or in real action. I can't always catch the Tournament of Roses parade.

Re: Building fully flexible tail (several joints) with minimal actuation required
 

Sanddrag,
It looks realy cool! Very robust and made to last. I hope it works as planned. Hey, what is your name anyway?

Re: Building fully flexible tail (several joints) with minimal actuation required
 

How about covering the whole tail in that black corrugated drainage pipe they sell at Home Depot? While the 4" stuff may be too thin, 6" looks (from the photo) to be just about right. It is stiff enough to hold its own and not get damaged from the knobs sticking out of the tail mechanism, felxible enough to bend just right, and it won't bend enough that the folwers will fall off or show gaps. Just thinking out loud.

Don