articulated fingertips

hello everyone

I hope this is the right space for this question and to get some help in understanding this mechanical concept please.
I am trying to come up with some articulated finger extensions for a costume. The best exisiting example I can give are the skeletal fingers of Death in BBC´s "The Hogfather".

As far from these pictures and from what I ve understood here on the website, the mechanics for hands is that there is a spring or recoil mech on the top of the fingers, and a pull mech on the underside, and restricions in the movement of the mechanic makes the finger curl. Is that correct? Because when applying that principle to the fingers extension, I have no idea from where to generate the pulling force. I d be super happy for some enlightment here, guys.

There´s some images of what little I have from my own mind and potato screen caps.
Thanks already


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    you guys do not know either?
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    Hi Wolf,

    In the case of finger extensions, the pulling force is created by the bending of the finger.

    This video may help you visualize the process:

    Here's one example that shows a possible linkage:

    And here as well:

    hope that helps.


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    wow Chris, that is super fast. I just sent the email.

    Alas, I do know all the videos, but they do not help me understand. All of these are basically not finger extensions(apart from the Xfinger), but hands worn on hands, no? And the XFinger mechanics, I can´t make head or tails off it I m sorry. I m not looking to create an extra hand, I just need one articulated fingertip on top. I simply do not understand the mechanical forces at work. The first video, I even have found hight res images of those extensions but they are ludicrously complicated and THICK while the Death fingers are super thin and light in comparison.

    Even when having a good metal spring in it, the finger bends, sure, but I need it to curl. You can see Death Fingers curl, and they are super thin compared to the others. Thank you for the help, but, maybe you have some more or can get someone else in the band to help out, please?

    Because either ppl do not talk about it or they dont know.
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    Hi Wolf,

    All of the videos above have curling fingers, but their design and materials differ.  In the example images you provided the mechanisms would be internal.

    Those executions may be bulky, but the same principals can be slimmed down.  For example:

    While this video is for a different type of finger extension, the mechanical linkage within the individual fingers are similar and the animation helps visualize it a bit better:

    Here is a better look at the linkages from one of the videos above:

    And here is a simplified cardboard example with oversized linkages to help illustrate:

    And here is an exploded breakdown of each component and how they connect to each other:

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    Wolf ReicherterWolf Reicherter ✭✭✭
    edited February 2017
    ooohhh, super nice Chris. Some I already new but the first 3D animation and the last schematic shall help me understand. Thank you. Much oblidged. Let see if I can wrap my brain around it now.
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    Just found this video that covers these as well


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    Is there a link to the diagram showing above with dimensions thats available somewhere. Ive been looking everywhere 
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    You can make up your own dimensions based on the size fingers/hands you are creating.  As a starting point, I would keep the scale relationship between the individual pieces the same, but you can scale it as large or small as you like.

    A good way to get started would be to print out the image and cut out templates and do start prototyping your design from there.

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    gary is the Master of these. In the end I just bought a pair of his 3D printed extensions. Wonderful product

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