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PETAL SPINE - flexibility and durability — Parallax Forums

PETAL SPINE - flexibility and durability

fuichrisfuichris Posts: 26
edited 2014-10-11 20:04 in Robotics
Hi folks,
Working on making a mechanical project to make an artificial flower move two of its petals using plastic spine within the petals, fishing wire, Parallax servo and a homework board.

See video: https://vimeo.com/108456552

ISSUE: the tiny (2-3cm) plastic spine (within the petals that makes it move) doesn't retract back to the original position after extensive use. Muscle memory not happening.

MATERIAL: I've tried tuperware plastics, folder plastics (see attached pics).

HELP! What kind of material is flexible enough in this 2-3cm size and retractable? Pls see the video.

Thanks!
IMG_7119.jpg
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spine - retractable.jpg
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P002_011113.jpg
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Comments

  • Mark_TMark_T Posts: 1,981
    edited 2014-10-09 05:47
    I'd look for something like transparent silicone rubber sheet - possibly consider
    sandwiching several thin layers together to adjust the stiffness,
    possibly looking at how leafsprings work for inspiration.
  • Hal AlbachHal Albach Posts: 747
    edited 2014-10-09 08:33
    If the sheath runs nearly the full length or can be made to run the full length to the servo I think a thin steel wire would give pull and push capability. Something like piano or guitar strings.
  • PublisonPublison Posts: 12,366
    edited 2014-10-09 11:20
    I would suggest hinges, (http://www.kavanrc.com/IndexText/0129E.html) , and a Push-Push method on the servo. It would require two strings up the tube. That way you do not have to rely on the petal to close it's self.

    A really good read on RC type linkages is at:

    http://www.bpesolutions.com/bpemanuals/Servo.Info.pdf
  • fuichrisfuichris Posts: 26
    edited 2014-10-09 19:06
    Publison wrote: »
    I would suggest hinges, (http://www.kavanrc.com/IndexText/0129E.html) , and a Push-Push method on the servo. It would require two strings up the tube. That way you do not have to rely on the petal to close it's self.

    A really good read on RC type linkages is at:

    http://www.bpesolutions.com/bpemanuals/Servo.Info.pdf

    HINGES - PETAL SPINE: unfortunately they would be too big as the petals range about 1.5-2cm, and secondly, the hinges would be too stiff...it needs to bend slightly.
    PUSH PUSH METHOD: yes, ideally if I could control it opening and closing, but it's a fishing line so pushing would be impossible, no? I've read the full document on RC type linkages and not sure how that would work in this case with fishing line strung up about 10-15cm of copper tubing. But the doc was a real informative read though. I'll start a separate thread on this i think :D
    Tks!
  • fuichrisfuichris Posts: 26
    edited 2014-10-09 19:19
    Hal Albach wrote: »
    If the sheath runs nearly the full length or can be made to run the full length to the servo I think a thin steel wire would give pull and push capability. Something like piano or guitar strings.
    Tks Hal!
  • Mark_TMark_T Posts: 1,981
    edited 2014-10-11 04:50
    stiff (stainless?) steel wire in teflon tube should work nicely - I've used spectra cord in teflon tube under high tesion force and its
    a great pull-only method, so little friction.
  • fuichrisfuichris Posts: 26
    edited 2014-10-11 20:04
    Mark_T wrote: »
    stiff (stainless?) steel wire in teflon tube should work nicely - I've used spectra cord in teflon tube under high tesion force and its
    a great pull-only method, so little friction.
    Let me try Mark, but I'm i'm hesitant because the wire will have is within a 15-20cm copper tube and that can't be changed...afraid it may bend at some point and replaced. But I like the prospect of a push/pull though.
    I'm currently testing the leaf spring method and fishing line...currently on it's 3rd day and going well. Needs to last 3 months ;p
    Tks!
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