Fuichris said:
The snapping into shape is because there is too much current.
Are you sure about that? I haven't looked into Flexinol; I've been leaving that up to you. BioMetal, as I mentioned, has a hysteresis loop in its thermal cycle. At low temperatures, you can pull it to about 105% (or whatever disappointingly small percentage) of its normal length and it will stay there. When you heat it, it doesn't react at all until you hit its transition temperature (let's say 150° C as an example, but I really have no idea) at which point it spontaneously snaps back to its "resting" length within a millisecond or two. You can't deform it again until it drops to maybe 120° (again, just an example). I thought that since you had settled on Flexinol, it must be more controllable, but maybe it isn't. Does the literature state that it is, or did you just buy some to experiment with? If the latter, maybe what I was thinking of as the way to go with BioMetal is worth trying. Instead of what you're currently using as a return spring, (I would be using a leaf-type (no, not because you're making a flower, smartass...)) try one that perhaps has a more aggressive progression factor. I don't know whether or not that can be accomplished with a single leaf, or if you would have to go with multiple leaves like in a car suspension system. The bad aspect of that is that unless you have some very tiny shock absorbers in your parts bin, it will uncurl just as rapidly at it would curl without the spring. That would be okay if the flower that you want to model is a Venus flytrap, but your pictures sure don't indicate that. :p The whole issue is why I was hoping that the metallurgy had improved significantly since I dealt with it, so that a gradual transformation could be achieved. It's obvious from that one video that it's possible with some memory substance, but I don't know what it is.
Aw, nuts! Now I'm starting to think that my design won't work either. :(
I'll keep thinking on it.
edit: Actually, I'm currently too tired to keep thinking on it. Instead, I'll resume tomorrow (well, later today).
