Material which is bendy at 80 C and stiff at 40C

I am building a handle for a concertina. Just as I am getting it finished, I have thought that I should have done it altogether
differently. Ah, that's life!
Man has risen from the apes because he can hold things with his hands, that involves the fingers, but with a concertina that is a problem because you want the fingers for pushing the buttons.
Some players use straps across the back of their hands, but I find that unsatisfactory.
So I making a "thing" which will lie in the groove at the backside of the gap between the thumb and the bony plate which makes up the hand. That way the palm of the hand can rest on the crown of the handle and the hand can be held onto it by gripping round the "thing" to pull the palm back onto the crown of the handle. Concertinas have to be played on both the push and the pull, but the forces are not very great.
So what I want is a material which is reasonably pliable at not too high a temperature, say 80C, though that's negotiable. The hand can take that for a few seconds while trying it out. Then the "thing" can pushed into shape and tried again. The pliable material can be covered with flexible material, say rubber, so that even if the pliable material is sticky, it won't stick to the hands. The pliable material is heated by embedded electrical wires, low voltage from something like a battery charger. When the material cools, it must stiff enough. Body temperature is 38C but I can't see a handle getting hotter than 30C in British conditions. It doesn't matter if the pliable portion bends slowly, it can always be heated up again and re-shaped. In fact the ability to re-shape would be an advantage.
Any suggestions?
Michael Bell
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Michael Bell wrote:

Talk to a friendly physiotherapist. They use a plastic material that will do what you want to make splints that mould to human joints. Heat in hot water until pliable then mould to suit. Fine adjustment with a hot air gun.
Bob
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On Fri, 21 Dec 2012 16:58:55 +0000, Bob Minchin

Greetings Bob, That plastic the physiotherapists use is great stuff. I was going to suggest it but you beat me to it. I had several splints made over the course of two years and one of the great things about the stuff was that after the swelling went down from a surgery and the splint loosened all I had to do was warm the splint with steam from a kettle and re-form the splint. And once cool the plastic was quite rigid. I saved the splints and now use the plastic on occasion for fixturing difficult to hold parts. Eric
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Michael Bell beweerde :

A while back "polymorph" was suggested here.
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On Fri, 21 Dec 2012 16:35:54 +0000, Michael Bell wrote:

Polycaprolactone it's called...
http://en.wikipedia.org/wiki/Polycaprolactone
probably available from eBay but definitely from the 3D printer people, search for Reprap and look for material suppliers.
- Brian
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On Fri, 21 Dec 2012 16:35:54 GMT, Michael Bell
Caprolactone polymer aka polymoph
http://www.remap-internet.org.uk/remapedia/tiki-index.php?page=Low+Temperature+Thermoplastic+-+Polymorph&highlight=polymorph
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On Fri, 21 Dec 2012 16:35:54 GMT, Michael Bell

Michael -
If you wanted a natural material rather than man-made plastics, it would be worth looking at the techniques used to make walking stick handles out of buffalo horn - that is basically a process of heating up the horn in hot water and/or steam to make it pliable. Similarly, worth considering bent wood techniques - laminate it out of several thin strips. The latter couldn't be re-shaped, but you could maybe do a prototype in plastic and then use it as a template for a laminated version.
Regards, Tony
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Thank you for that. I am using modelling clay to design my shape, much delayed by Chistmas-New Year festivities. As to the rest, one of the problems which I didn't mention was weight. Many play the concertina on their knees, but I want to hold it. It is a lightweight instrument, and I don't want to add to the weight.
Regards and a Happy New Year.
Michael
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http://www.alumilite.com/howtos/SlushCasting.cfm
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On Mon, 31 Dec 2012 06:30:58 GMT, Michael Bell

I thought it was more usual to play it sitting down... ;-)
I'll get my coat...
Regards, Tony
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