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  1. #1
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    Default I need help with a kinetic machine

    Hello Everyone,

    My name is Gavin and I am 50 years old - I want to make this kinetic structure - that of Arthur Ganson's Exploding Yellow chair

    Arthur Ganson - Little yellow chair - YouTube

    I can not get it clear in my head how to design the dwell action to stop the process can anyone help.

    The entire cycle lasts 22 seconds and the rpm of the motor is 27 rpm if I have counted correctly

    I have a thought pattern to do away with the mechanical version and go a stepper motor - but I transfixed to not let it beat me (a purist if you will).

    I am of the mind machinists are an extremely strange breed of men - I still love my profession

    If anyone can help it would be greatly appreciated.

    Kind Regards
    Gavin

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    WTF? You should ask your doctor if Zoloft is right for you. Seriously...what dwell are you talking about? Do you mean when the chair comes together you want to stop it in the assembled state momentarily?

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    pretty sure he means the variable speed at which the individual segments are driven. you can see the entire belt drive to all the segment actuators varies in speed so the ratio change happens at the input.


    this would do it.

    perhaps with a missing tooth for the slight pause?

    oblong gear - Google Search

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    That's a neat mechanism. Watching it in slow motion, it looks like the main drive runs at a constant speed. The second drive (with the short spinney bits that look like anemometers) runs fairly slowly through most of the cycle, then speeds up as it's almost closed and stays sped up until the dwell is complete and it has opened. The dwell looks to occur between the second drive and the link arm assembly.

    Without a close up, it's hard to say how it works. You could do it with a stepper, but that misses out on a lot of the coolness.

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    Google "ingenious mechanisms" good book


    Sent from my iPhone using Tapatalk

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    I'm guessing you want the mechanism to stop briefly at the complete end of the cycle.

    There are lots of ways of doing this, usually in volving cams or cam like mechaisms. Have a look at Dr Thangs animations on youtube e.g.

    Linkage for oscillation with dwell 1 - YouTube

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    I would agree that doing this with stepper motors would totally remove the cool factor. You can make just about anything do just about anything with steppers but then it is just a common robotic function. It's all in the gearing.

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    Quote Originally Posted by Billtodd View Post
    I'm guessing you want the mechanism to stop briefly at the complete end of the cycle.

    There are lots of ways of doing this, usually in volving cams or cam like mechaisms. Have a look at Dr Thangs animations on youtube e.g.

    Linkage for oscillation with dwell 1 - YouTube
    This is sort of what I had in mind. The arms are on a sort of springed dog clutch or similar, with possibly a friction clutch to help the arming, watch the flys (the anemometer looking things), they chug along then speed up- spring fully armed- arms come in under spring pressure then slight lag as the clutch catches up once the chair is together. Since all are on a toothed belt it's timed, and without thinking too deeply into it really only needs one of the arms to have the clutch.

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    I think it would be a lot more fun to design your own machine. I wouldn't have much fun reverse engineering someone else's thing and then building my own. Use your own ideas and fool around until you figure something out.

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    Quote Originally Posted by John Welden View Post
    I think it would be a lot more fun to design your own machine. I wouldn't have much fun reverse engineering someone else's thing and then building my own. Use your own ideas and fool around until you figure something out.
    I agree but you learn a lot reverse engineering. It often humbles then if you have the goods inspires.

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    Thank you for your replies, assistance and thoughts.

    I like the igneous mechanisms book idea.

    The you tube link I have seen and will continue to struggle though.

    The momentary stop does occur at the secondary point of drive - the main motor is a constant velocity the driven drives the chain - you will notice the arm with the long prongs rotating it catches on a cam and at a point aligns to momentarily stop the rotation.

    There is a blurb that explains the process - it is in German and English

    I am struggling to get the visual arrangement in my head to get some numbers to a drawing.

    With being a manual machinist the manufacturing of components to their "fit for purpose" end point is a long road pavement in failure and constant tweeking

    Reverse engineering is an interesting concept something us machinist do every single day - introduce me to the next unique idea if you can find one the closest I have seen is the POCKET CNC machine - the idea of doing this was to achieve an engineering capacity to apply to other design ideas as well pay tribute to the original guy (most definitely not take any false credit).

    The artist is amazing and well worth a look for his old school approach to engineering concept - I have made his wire gear tool and it works amazing and have made several gears and have plans to use them in kinetic machine of my own.

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    I think it uses a scotch yoke sort-of thing incorporated into the mechanism. Arthur Ganson has made some pretty neat pieces.

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    Assuming we're talking about the moment when the chair is together, to me that looks more like a kinematic motion where the velocity becomes zero just for an instant, rather than a non-zero dwell length. That can be arranged with four-bar linkages (also planetary gear arrangements which are kinematically equivalent), as an alternative to cams.

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    Just fuel for thought...
    if you look at a crankshaft and connecting rod, you see fairly smooth motion.
    Now try to shorten the connecting rod so it is almost as short as the throw of the crank..
    It will dwell for a while at the bottom of the stoke, and speed way up at the top of the stroke..
    Ultimate would be a connecting rod as short as the crank throw.
    It will actually try to dwell for 270 degrees of crank rotation. (if it doesn't jam up)

    Combine that short con rod idea with a four bar linkage and you might have what you want to do, or some new variation.

    This might inspire some thinking for what you are trying t do..

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    Thanks 3t3d Diamond - I think it is a case of taking all suggested answers and trial and error - the combination of crank concept with a four linkage system is the go with sprag bearings on each station

    I am a visual learner and trial and error is me
    Last edited by curseperfection; 05-05-2016 at 09:47 PM. Reason: did not feel comfortabel with first response

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    This might help a bit, especially if you can slow it down- https://vine.co/v/OwnpmQY3L9F

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    +1 for anything Arthur Ganson has made. I was lucky enough to see one of his exhibits locally about 5-8 years ago. I tried (unsuccessfully) to copy-ish a couple of his pieces, just to see if I could do it. He is absolutely brilliant at coupling mechanical constructs with organic, vegetable pieces.

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    I still prefer the bottle opener by Rob Higgs. Gadget Man Bottle Opener - YouTube

    His knife is also an elegant textbook of interesting mechanisms. Rob Higgs - The Knife for Heston Blumenthal's Perfectionists' Cafe - YouTube

    Larry

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    Quote Originally Posted by L Vanice View Post
    I still prefer the bottle opener by Rob Higgs. Gadget Man Bottle Opener - YouTube

    His knife is also an elegant textbook of interesting mechanisms. Rob Higgs - The Knife for Heston Blumenthal's Perfectionists' Cafe - YouTube

    Larry
    Rob Higgs' YouTube channel should pick up a few new subscribers as a result of this post.

    I'm one of them.

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    My favourite piece of Arthur Ganson's work is the baby watching the ball

    I am buying an Orion Pulse Arc welder to attempt something like a wire sculpture - I live in Australia so the Aussue Dollar is not what it use to be and currently all unused machines (not that many - mainly wood working hand me downs from my father) are for sale so as to afford this machine.

    I have tried soldering / brazing brass and stainless steel rod the impatient side of my personality can not cope with it not being easy and perfect so pulse arc welder is the next must have.

    Working with metal is such a privilege - so much can be achieved with a welder / grinder / mill + lathe - I have been doing machining for 35 plus years and have loved it day one.


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