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Topic: Perpetual Motion Coin Myth. Can Anybody do it?
Message: Posted by: Carron (Jan 30, 2005 02:37PM)
Hi there guys, I was having a look through my AoA series today and I came across this in book one. Can anyone here do it?

Message: Posted by: Jonathan Townsend (Jan 30, 2005 02:57PM)
I got as far as two spins and then got tired of picking up coins off the floor after they roll all the way across the room.
Message: Posted by: mike gallo (Jan 30, 2005 06:46PM)
I have never tried it... but I have seen a person doing it with poker chips in a casino once.

Message: Posted by: Jonathan Townsend (Jan 30, 2005 06:55PM)
Somebody gonna make up a set of coins that lets you do this ;) ?
Message: Posted by: Daegs (Jan 30, 2005 10:10PM)
Dr. Jakks claims he could do it for 30 seconds or more I believe....

Message: Posted by: Shane Wiker (Jan 30, 2005 11:04PM)
Awhile ago, I was able to do about 8 spins.

Shane Wiker
Message: Posted by: tgroenjes (Jan 30, 2005 11:54PM)
I read the other thread on this, and it sounds like a great flourish. I will have to give it a try. I also noticed that quite a few people were asking for 'proof' that this could even be done, but no one ever posted a link to a video. They even said they didn't care if it was for only 5 seconds, they still wanted to see it done. So, does anyone have a vid of it? Or a cam so they can video it?
Message: Posted by: MrCyNic (Jan 31, 2005 04:51AM)
I commited a full day of my life to this once.

I got as far as two full rotations, but the motion would always stop. I switched coins and got three rotations. Progress, I thought.

Only it wasn't. I stalled at three.

Switching back to my first set of coins, I was suddenly stuck back at two rotations. Switched back again. Three rotations.

Eventually, I worked out that the number of turns I was getting was directly related to the surface contours of the coins I used. The milled surface of the rotating coin was following the contours of the supporting coins, turning as it did so. Once it reached a countour it couldn't negotiate, it jammed.

My guess is that those who've had greater success with the move have found some way of getting around the contour jam, or just have a better understanding of how the wretched thing's supposed to work.

Whenever the topic crops up, I consider going back to AoA and trying to learn the move. Then I remember the day I committed to it and wonder what else I might have been doing with that time. Like buying grapes, for instance.

I could use them - the ones I'm chewing on now are awfully sour.


Message: Posted by: IanKendall (Jan 31, 2005 05:10AM)
Right, I played with this a while ago, but now I think I've found a new target for my obsessive nature. No rest till it's taped :)

Take care, Ian
Message: Posted by: Carron (Jan 31, 2005 08:21AM)
Thanks guys, good to see so many responses in such a short time, I look forward to see a video of this somewhere

Message: Posted by: Dean A (Jan 31, 2005 08:27AM)
On 2005-01-31 06:10, IanKendall wrote:
Right, I played with this a while ago, but now I think I've found a new target for my obsessive nature. No rest till it's taped :)

Take care, Ian

I imagine that fathering two infants is quite enough for your obesessive nature right now.

Message: Posted by: IanKendall (Jan 31, 2005 09:55AM)

I'm still borderline obsessive/compulsive (and teetering on the wrong side of the border, at that). Have a look at the link below for some of my output!

How's you brood coming on?

Take care, Ian
Message: Posted by: BlackShadow (Jan 31, 2005 12:50PM)
I'm assuming this the effect with one coin spinning between two others.

You need to give some input to the system in order to compensate for the bearing friction and air resistance losses. Presumably this takes the form of rotating the bearing using a smaller radius in the direction of rotation of the inner coin, the same as swinging a weight on a rope. (I don't have the benefit of having read AoA). This force has the effect of destabilising the coin, and the only restoring force available is an increase in reaction force to produce more bearing friction. This in turn slows the coin faster and also contributes to an unstable sytem if the axis angle tilts of 90 degrees. In other words it can't be done consistently for any length of time, because the forces at the bearings are forever liable to spiral out of control until the friction can't hold the system together.

I'd suggest two gaffed outer coins with minute jewelled bearings inset and matching minute spindles on the inner coin. A pretty effect is thus produced which you could keep up for 1 or 2 minutes while you patter about perpetual motion or crack some jokes. The minute bearings are hidden by the bulk of the coins. You could then hand the coins out for examination, but effect a CP switch for 3 plain coins, and of course the spectators have no chance of repeating it.

Another way of producing it may be strong magnetic bearings in the outer coins and a 2mm diameter steel rod drilled and inserted on a diameter of the inner coin. A switch would be needed for examination but the bearings would be to all intents invisible, thus strengthening the effect.
Message: Posted by: ragtop (Jan 31, 2005 12:53PM)
I gave up trying to get this one down.
Message: Posted by: BlackShadow (Jan 31, 2005 01:43PM)
I'm now thinking all that would be needed is a drill and a couple of small ball bearings. Drill holls in the centre coin on a diameter and inset 2mm ball bearings with superglue. Drill small pits in bearing coins. It could be cheap to make and invisible from 6 feet away.
Message: Posted by: IanKendall (Jan 31, 2005 02:18PM)
That's cheating :)

Take care, Ian
Message: Posted by: BlackShadow (Jan 31, 2005 02:33PM)
I know! But so is "perpetual" motion done the hard way, cos you need some input to the system to keep it going. Let us know if you have any success without cheating ;)

I've had a further thought as well. The centre of the the 2 coin has a small circle on the tails side and I've got it going for 7 or 8 spins. More practice may mean better results. Or you could make a semi gaffed version by hollowing out the the metal in the circle just slightly. This might bear casual examination if you did it on all three coins.

(Love your site BTW. Very entertaining vids)
Message: Posted by: BradleyNott (Feb 1, 2005 12:13PM)


There is no such thing! It's all about efficiency. Is spending frustrating years trying to perfect an insanely difficult feat of juggling efficient if the same feat can be acheived with a gaff? Is the work for your sake or for the effect's sake?
Message: Posted by: IanKendall (Feb 1, 2005 12:19PM)
It's _entirely_ for my sake. I enjoy overcoming challenges, and to use a gaff (for pretty much anything) just does not satisfy me.

Take care, Ian
Message: Posted by: BlackShadow (Feb 1, 2005 12:32PM)
This would be a pretty flourish if it were possible to do consistently. One has to ask the question why it isn't sprinkled all over the magic texts, like the coin roll or the roll out. Now both of those seem pretty impossible when you first start working with them, yet they are achievable. I wonder if that's an omen.
Message: Posted by: harris (Feb 1, 2005 04:41PM)
I am guessing that Roy Kuepper who makes some interesting coin toys er profesional props could come up with something. He has some coins that spin on a different axis.

Harris Deutsch