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Flexinol 'Muscle Wire' — Parallax Forums

Flexinol 'Muscle Wire'

manxstampmanxstamp Posts: 57
edited 2005-03-01 03:04 in General Discussion
Having read the books about the Stiquito robot, I decided to build one. This robot has so-called 'muscle wires' made of a nickel-titanium alloy called nitinol (trade name Flexinol) which contracts when heated by passing a current through it. Nitinol has many medical uses, including making 'stents', small mesh tubes which expand in coronary arteries to reopen·narrowings.·There is a new book coming out about a microprocessor controlled version of Stiquito and the other books mention using a Basic Stamp to control the current via a Darlington array. This made me rather rashly invest in some Flexinol and Stiquito kits for a project to build a stamp-controlled 'muscle wire' walker.

I don't know if any of you have tried building a Stiquito. It is a nightmare! Think of precisely placing knots in·several short·strands·smaller than·the finest human hair and then crimping it in tiny sections of small aluminium tube. Finally, after many a 'robust expression',·I took to using·some microsurgery equipment (in electronics it helps to be medical - artery forceps·make excellent heatsinks for example) and built the damn thing·over three frustrating evenings. I now have a tiny feebly twitching 'stick insect' which walks precisely nowhere as it cannot grip any surface and overcome its own inertia. It is an understatement to say that it was a great disappointment.cry.gif

So before I decide whether to even bother to try anything more, I should be interested in any other experiences with this curious metal, particularly anything positive!·Otherwise, I will not pursue it further.


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Manxstamp,
Isle of Man, British Isles

Comments

  • Robert SchwartzRobert Schwartz Posts: 141
    edited 2005-02-17 03:28
    I too built the stiquito. The only way to do it well is with a magnifying glass and patience. I went through a bunch of wire and piano wire before I got it to work well. It just takes time. Also, building a microcontroller based stiquito will be very hard. They have tiny bases and can't carry much load. If you want to build a microcontroller based muscle wire walker howver, get some higher strength flexinol, and use the lightest materials available.
  • The Dead BugThe Dead Bug Posts: 73
    edited 2005-02-18 01:33
    I agree with Robert, I built the Stiquito, and it did work, but in a former life I was a watchmaker (no, really!) and I have the loupes, the tweezeers, and the patience to work with the hair-thin nitinol. I tried having a few of my students work with it in a lab once and it was a disaster.

    The stuff is fascinating and I think it has tons of potential in robotics, but it's not for the faint of heart or the far of sighted. [noparse];)[/noparse]

    Manxstamp, I would encourage you not to quit on it now, now that you know what this tempermental stuff needs to make it work. You have so much invested in the learning curve already!

    Bruce

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    Name: Bruce Clemens

    Work:· Clemensb@otc.edu
    Good Stuff on my Bolg: http://theDeadBug.journalspace.com
  • WhelzornWhelzorn Posts: 256
    edited 2005-02-23 18:17
    I tried building this damn thing as well. I had all the equiptment required to do it, and I built it without much frustration, but then I tried to make it walk. well, the walking gait made no sense because it doesn't lift it's legs, so it would be better off throwing it's legs foreward all at once and hoping the nitinol expands slow enough to pull the weight foreward. The other problem was crimping it. It does not hold on to the nitinol firmly enough, because it's really slippery, and you cannot solder it for obvious reasons. So the brilliantly designed insect ripped it's own muscles out of the crimps, and if the crimps were strong enough, the piano wire was too stiff, snapping the nitinol in half.
    Anyway, if you wanted to, you might be able to use conductive epoxys or metal filler to hold the nitinol in place instead of crimps, and hopefully the epoxy is stronger than the nitinol.

    Justin W.
  • CharlesCharles Posts: 3
    edited 2005-03-01 02:09
    I wonder how a tiny drop of silicone adheasive would work as a non-slip foot for this project?
  • dandreaedandreae Posts: 1,375
    edited 2005-03-01 03:04
    Charles,

    If you want to try, I will send you a kit for free.· Please send me your mailing address.

    Dave





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    Dave Andreae

    Tech Support
    dandreae@parallax.com
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