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excelfreak

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Hi guys,

I was in a magic store (an ordinary store selling magic tricks) and saw something called an expanded shell coin. In essence it is a silver half dollar (they had quarters and other coins too) that somehow has been cut out and then stretched so that it fits over an ordinary silver half dollar. With some clever manipulation and misdirection feats that look like miracles can be shown.

Now I am not a magician (neither am I a machinist) but I was wondering, how would one make a coin like that?

The outside of the coin was still knurled yet it was larger in diameter so that it fit over a regular coin.

I can figure out the "cutting out" part, but how do you "expand" a coin?

Any ideas how this is accomplished?

Curiosity is killing me.


Here is a link to one of those - there are literally hundreds of manufacturers.

http://www.johnsonmagicproducts.com/shop/index.php?main_page=product_info&products_id=44


Thanks

excelfreak
 
I don't think its a modified coin, but rather a fabricated coin.
 
I don't think it is fabricated - the coins looked perfect - and they had numerous varieties, quarters, Kennedy halfs, Walking Liberty, Morgans - it would take a real expert to copy a coin. Casting doesn't produce this fine detail, e.g. you could clearly see each feather on the eagle. Very very fine detail.
 
I can think of no manufacturing process that can uniformly stretch the existing surface contour of a coin.

If they look perfect, then they are probably stamped out of Cu-Ni plated copper sheet, just like regular coins are. . .
 
I agree - I cannot think of any manufacturing process either, hence my question. However, I am convinced they were modified. Since they have different coins you would think they all cost the same, but they don't! A Kennedy half from 64 (which is silver) costs more than a quarter (accounting for using an actual coin as raw material). A silver Morgan costs even more as the base coin is more expensive.

Wouldn't it also be cost prohibitive (and unlawful) to make those dies to stamp the coins? Given that this is a magic gimmick and they will not sell 100,000's of them?


Perhaps someone knows.
 
I don't think they are modified coins, and I'm pretty sure that's illegal anyway. But don't quote me on that.

But to scan a coin and enlarge it a hair and stamp out one doesn't seem that hard. It would be interesting to know how they make them.

I googled a couple of videos and they can pull off some pretty slick tricks whith those!

John.
 
I don't wear finger jewelry, but those rings are cool. All the detail is still preserved, that's pretty amazing. I would have thought by deforming it to such a degree it would be just plain metal at this point.

Damn, now I want to know how they make those too.... ;-) although the engravings kind of give it away. They probably drill a hole and then pound it on a tapered mandrel.

But how would you stretch a coin?

If you hammered the coin flat - which would make it increase in diameter - its thickness would be less. So if you subsequently cut out something so that it could slip over another coin it would not cover the coin completely. The ones I saw did. These "shells" where larger in diameter and height to conceal a regular coin.

Mysterious......
 
I just did some googling of expanded shell coins and how to make them. It's pretty clear that they are real coins that are, indeed, expanded. There is one person I found who is selling plans, and says a lathe is required. I'm guessing that they hollow out the coin first, machine an anvil to be a press fit in the machined hole, and then give it a whack with a plastic or leather faced mallet. May have to repeat a few times with slightly larger diameter anvils, and may have to anneal the coin to get it to expand without ripping. Very similar process to how the coin rings are made.
 
oh, and as to legality, I researched this when I was doing coin rings. Not illegal to modify a coin unless you are doing it to defraud someone.
 
If they are modified coins, someone knows how to make them. . . .
 
There are some magic forums too, where people discuss these things, but they are all so dang secretive and proprietary.
 
Title 18, Part 1, Chapter 17, section 331 of the US Code states:


"Whoever fraudulently alters, defaces, mutilates, impairs, diminishes, falsifies, scales, or lightens any of the coins coined at the mints of the United States, or any foreign coins which are by law made current or are in actual use or circulation as money within the United States; or
Whoever fraudulently possesses, passes, utters, publishes, or sells, or attempts to pass, utter, publish, or sell, or brings into the United States, any such coin, knowing the same to be altered, defaced, mutilated, impaired, diminished, falsified, scaled, or lightened— Shall be fined under this title or imprisoned not more than five years, or both."


I'm not a lawyer. That being said, I see two ways to read this.

(1) you cannot fraudulently mutilate a coin
or
(2) you cannot mutilate a coin.

Either way, you can bet I'd be seeking legal advise prior to modifying any US coin for profit. . . .
 
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they are allowed to be secretive about their craft and their illusions
this is purely a "how do they make this item" kind of question

Paulsv - where did you find the guy that sells the plans? I have been googling this for days and not found anything but retailers and tricks. Do you have the link? I would like to look around there.
 
Entropy

I'm no lawyer either, but I think the "fraudulently" applies to all subsequent words.

Making a ring out of a coin is not a fraud - but art. Similarly making a trick coin for a magician is not fraudulent either. I think what they meant is - don't melt coins down for metal value - or shave stuff off - or take a silver slug and imprint a higher denomination.

Furthermore, all these folks are still in business - i.e. have not been shut down - so I guess its ok.
 
But what happens to the metal that is machined away from the expanded shell? Wouldn't it be unlawful to recover and profit from that shaved away silver?

Just playing devils advocate :hDe:

An expanded shell coin has been defaced - in that one face of the coin was literally removed.

An expanded shell coin has been lightened - in that a significant amount of material was removed.

An expanded shell coin has been scaled - in that the size of the coin has been enlarged.

It's reasonable to say that an expanded shell coin has been mutilated.

You could also say that the coin has been impaired, and diminished.

Here's where it gets interesting - you could even make the case that the alteration was done with the intention to commit fraud - aka to deceive -as deception is the root of all magic tricks, right?

After giving it more thought, I agree with your assessment - in that modifying a coin for a magic trick is probably legal. Mainly because the coin is being sold for significantly more than face value - it is not being spent for a false value.

Also consider those penny smashing machines that you see at science museums - those appear to be factory manufactured legal devices, intended to deface US coins for profit. . . .
 
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now that we got the legality clarified lets refocus on the puzzle at hand ;-)

how do they make them
 
Here’s how I think it’s done.

Step 1: machine socket into back of coin.

Step 1.1: heat coin and quench to anneal.

Step 2: place coin over an expandable mandrel. (similar to what’s used to expand exhaust tubing – however this mandrel is made to grip within the shallow depth of a coin.)

Step 3: slowly expand coin.

Step 3.1: heat coin and quench to anneal again, if unable to reach desired diameter with one plastic deformation (cracking).

Step 3.2: continue expanding coin to achieve new diameter.

Step 4: touch-up machine the socket for a final fit.

I think we’ve got it!
 
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The lost wax casting process is easily capable of reproducing coin detail , the "secret" is how to make a pattern that is larger than real.
There are pattern plasters that expand on setting , this is one method that could be used. Injecting wax under pressure into a flexible mould could also be used.
I have some experience in the latter and it does work.
 
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