Need help with nitinol motor Bribe offered

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Subject Author Date
Need help with nitinol motor Bribe offered Larry Snyder 07-04-2008
Posted by Larry Snyder on July 4, 2008, 3:48 pm
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HI All. I am developing a motor using super elastic nitinol wire and have
problems.
Picture at: http://www.pacificsites.com/~snyder/motor.jpg The most
frustrating problem is joining the wire together. I bought some tiny
stainless steel tubing from Ebay. The idea is to use this as a sleeve and
solder/braze it together. It hasn't arrived yet. I have been unable to
find small high pressure crimp fittings.
The second problem is the wire slipping on the pulleys. I will send anyone
coming up with a solution to either of these problems a piece of wire to
play with, assuming it is something I can use. Wire description at:
http://www.pacificsites.com/~snyder/Ebay/Flexinol%20Test%20Data.htm
This wire has a transition temp ~100C. This helps resolving the cooling
side. The heating side can be easily insulated with cheap
materials(styrofoam). I am hoping to put this on a bicycle and operate with
solar power. Any comment/suggestions are welcome. Thanks in advance.
Larry




Posted by Larry Snyder on July 5, 2008, 1:32 pm
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> HI All. I am developing a motor using super elastic nitinol wire and have
> problems.
> Picture at: http://www.pacificsites.com/~snyder/motor.jpg The most
> frustrating problem is joining the wire together. I bought some tiny
> stainless steel tubing from Ebay. The idea is to use this as a sleeve and
> solder/braze it together. It hasn't arrived yet. I have been unable to
> find small high pressure crimp fittings.
> The second problem is the wire slipping on the pulleys. I will send
> anyone coming up with a solution to either of these problems a piece of
> wire to play with, assuming it is something I can use. Wire description
> at: http://www.pacificsites.com/~snyder/Ebay/Flexinol%20Test%20Data.htm
> This wire has a transition temp ~100C. This helps resolving the cooling
> side. The heating side can be easily insulated with cheap
> materials(styrofoam). I am hoping to put this on a bicycle and operate
> with solar power. Any comment/suggestions are welcome. Thanks in advance.
> Larry


HI All. I posted this on several newsgroups and got a lot of responses. I
would like to thank everyone for their input.
The answers that I like are:
capstain/multiple turns around pulleys
use tubing for guide and spot weld
grooving pulleys for more surface area
crimp fittings from fishing supply store
idlers/belts to apply extra pressure on pulleys
Answers I didn't like:
coating pulleys with nonslip stuff- wire pressure too great. will fail too
fast.
I have notified people with the above ideas and will offer wire only for
some other ideas.
Thanks for your interest.
Larry



Posted by John Nagle on July 7, 2008, 4:09 pm
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Larry Snyder wrote:
>> HI All. I am developing a motor using super elastic nitinol wire and have
>> problems.
...
>> I am hoping to put this on a bicycle and operate
>> with solar power.

This is one of the more inefficient schemes for converting
thermal to mechanical energy ever developed. Only a tiny fraction
of the energy in the water bath (on a bicycle?) will be transferred
to a thin wire running through it. Nitinol only converts a few
percent of the heat energy to mechanical energy. So you get to
multiply the efficiencies of two low-efficiency processes to get
a very tiny number.

Nitinol is mostly a solution looking for a problem.

> HI All. I posted this on several newsgroups and got a lot of responses.

Please don't do that.

                                        John Nagle

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