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Possible to make a 9.55" diameter Conical spring on my own?

  1. Jul 24, 2016 #1
    Hello all,

    I am 100% untrained in even reading about spring making let alone making them. There's a project I want to complete though and I need to make some props involving them. I say these conical springs would be roughly the diameter of a basketball to start with (9.55") and cone to a point for a very basic explanation.

    The image I attached is the best form to show what I'm trying to accomplish. I'm looking to make some costume props (4 exactly) resembling arms that would be attached to the person's back, be held down, and spring out when released and return when not in use. Ultimately the four "arms" would point to the front like in the image as well though not looking for springs to do all of that on their own. I will make some sort of wire attachment so the wearer can guide them.

    I'm posting here in hopes of getting a direction and not necessarily a complete guide on how to accomplish this though more information the better. From what I've been told so far this seems like a very near impossible tasks (this came from a veteran Mechanical Engineer so I'm guessing I'm above my head here) but I still have interest in making it work. If anyone can give some pointers or simply a direction for me to go in order to figure this out, it would be much appreciated.
    maxresdefault.jpg
     
  2. jcsd
  3. Jul 24, 2016 #2

    Tom.G

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  4. Jul 25, 2016 #3
    Thanks. I've been googling for results already, watched videos, and even found the document you suggested. Was hoping for some more insight since I can struggle a bit to learn just from reading. Thank you for the input again.
     
  5. Jul 25, 2016 #4

    Mech_Engineer

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    The manufacturing equipment for larger springs is very large and strong, due to the forces involved in bending large coils of metal. Whether you can make the spring yourself will depend on the diameter wire you want to use for the coil. I would say that for anything larger than maybe 0.25" the forces to bend it would be prohibitive.

    Have you looked to see if there's anything available that you can buy to achieve what you want? You may be able to achieve what you want without a large spring, maybe smart application of wires and slides...
     
  6. Jul 25, 2016 #5
    Thanks for the input.

    I haven't figured out what the diameter of the wire itself would need to be though I know the two bottom arms would need to be heavier than the top. I would need the springs to hold itself in shape with fabric being wrapped around it. Fabric wouldn't be too heavy, least hope not, and would resemble something like a spring wire hamper that you can fold up and pop out when needed.

    Unfortunately these hampers don't come in a long enough size nor have I seen anything that I could use instead of making it from scratch myself. Had a good suggestion on reddit to check out sky diving places in my area and see if I could use there old deployment springs shown in the image below but they also don't seem to be long enough. I'll keep looking though. Thanks again for the suggestion.

    ResvSpring.jpg
     
  7. Jul 26, 2016 #6

    Mech_Engineer

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    I kind of get the feeling you'll have a hard enough time figuring out how to mount these large arms on a person's waist. Any spring would wobble and oscillate with motion, and you would have to guide the motion with some linear guides. Sounds like a little too much complexity for a start... maybe consider arms first and see what problems you run into before trying to make them spring out?
     
  8. Jul 26, 2016 #7

    Nidum

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    Pneumatic sausages .
     
  9. Jul 26, 2016 #8
    Thanks for the reply.

    Do you mean I may want to work on making the arms with springs but focus on just having them be stable or to not use springs at all? If with springs, wouldn't the same issues be present or does creating springs with the ability to spring out make it that much more complex and a lot easier to not worry about that aspect?

    What I have in mind is having lines of wire connected down each arm in hopes that would keep them in line enough when they are released.
     
  10. Jul 26, 2016 #9

    Mech_Engineer

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    Well maybe I need to understand your concept better to make a real decision. I'm imagining that you basically want a spring at the wearer's waist, and when triggered the spring would cause all 4 arms to "spring forward" as if attacking. Is this somewhat accurate?
     
  11. Jul 26, 2016 #10
    In the simplest form yes though I'm not looking for the springs to do all of the work nor do they seem possible to do so. I would have the springs attached to something which would be held on the back and held down by a belt of some sort. When the belt is released, I would like them to simply extend to their full form and have some sort of wire or rig to guide them to the front and resemble something like in the picture I posted. Mainly want it this way not just for the effect but also to allow the wearer to move around easier if there isn't the best of space for having the arms extended.
     
  12. Jul 26, 2016 #11

    CWatters

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    I think Nidum has the best suggestion. If you can make the arms inflatable then they will pack away and can be made to "spring out" simply by inflating them from a small air or C02 tank.
     
  13. Jul 26, 2016 #12
    Have you thought about the safety issue involved with springs?
    Springs in the compressed state store energy, and depending upon how robust the springs are the release of energy can be problematic. There is a chance that one may release accidentally. If not following the direction of a guide wire, anyone in the vicinity of its extension can be whipped in the face and lose an eyeball. I think you have to take into account the welfare of your performance actors with whatever design you come up with other than springs. You need something that is reasonably controllable.
    And, putting the springs back into the receptacle is unwieldy.

    The air sausage is a good suggestion. It may extend more slowly than a quick spring, but than can be more of a "wow" experience for the audience with the stage presence and background music leading up to a full extension. The drama of suspence can be more entertaining than quick actions. But that is not what you are asking, so forgive me if my response is overextending.

    Othe ideas would be something along the lines of a telescoping antenae, or one of those extending arms and hands that one sees in cartoons ( forget what they are called ). Good thing about them is that they are fully and easily retractable, and more rigid along the length. As is the air sausage.
     
  14. Jul 27, 2016 #13
    I have not so thank you for bringing it to my attention. In no shape or form do I have experience with springs, especially how to make them, so I've been researching them which led me here. With that in mind I probably won't be pursuing spring use in my project.

    Not sure what you're referring to by cartoon extending hands but the telescoping option doesn't seem like a good fit. Using air to inflate them some how seems like the next best avenue to go. Thank you very for the input.
     
  15. Jul 27, 2016 #14

    CWatters

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    One problem I see is with the weight of the arms causing them to droop. I think that could be hard to solve whichever method you use to make them extend.

    I think the cartoon extending hands use a scissor like mechanisim...

    OperatorXXXXXXXXXXXXXXHAND
     
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