Expanded coin making

[raynerd]

I've always been into magic just for fun, I'm no good but always been impressed by it. One gaff coin I've made on a few occasions is a shell coin. It's just a coin totally 'bored' out so that it sits over another coin. They are very effective, I've a £2 I made that sits above a 10p, 20p, 2p or 1p and you can do some nice tricks with it. I've not tried it yet, but you can also turn down an identical coin I.e bore out a 10p and turn down the rim of a 10p so that the turned down 10p sits inside the shell. As you can imagine. They hold together looking like a complete coin and yet drop out to give the illusion of a new coin appearing.

There is something called the expanded coin shell. This is 10p or £2 that has been hollowed or bored out to create a shell but also "expanded" so it sits over an original matching coin (as apposed to the above, where the coin needs to be turned down). I'm curious to know if anyone has any ideas as to how to go about making one? Magicians say they show signs of stress so they are clearly made from originals. Anyone any thoughts as to a process of making these?

Looking forward to your replies.

[chipenter]

It's got to be like a very small english wheel , after it's bored out .

[BillTodd]

The press shop guys at work, use a thing like an expanding collet to expand rings. (I'll ask about it when i next see them) .

typically, expanding metal, for curved seems etc. is done by  gripping with a split jawed 'vice' with a tapered wedge (*or rocking jaws) that pushes the jaws apart as the gripping force is applied . The motion only moves a few thou" .

I would have thought, that a set of segments making a disc, tapered on the inside at an oblique angle , could be  fitted inside the bored coin. If the segmented parts are pressed by another tapered part it would stretch the coin.

* shrinker-stretcher jaws http://www.frost.co.uk/shrinker-stretcher-spare-shriking-jaws.html and taper type https://secure.wf-api.com/www.daggertools.com/3m5/metal-shrinker-extended-reach/shrinker-stretcher-jaws.html

[awemawson]

Is "defacing the Coin of the Realm" not still a treasonable crime 

I don't think we can come and visit you when you're banged up in the White Tower awaiting execution 


(Coinage Act 1971 makes it a criminal offence)

[RobWilson]

I just knew that was coming   


Rob

[Arbalist]

(Coinage Act 1971 makes it a criminal offence)

Apparently not. This page says it was repealed in its entirety in 1981:

https://en.m.wikipedia.org/wiki/Elongated_coin#Legality

They refer to this page.

https://en.m.wikipedia.org/wiki/Forgery_and_Counterfeiting_Act_1981

[awemawson]

Spoilsport 


 .... but imagine the YouTube video of his execution on Tower Hill - now that WOULD go viral

[NormanV]

I remember the time that I wanted some "Penny Washers". I found that they were 3p each, so I drilled some 2p coins and saved money!

[raynerd]

I just knew that was coming   


Rob

Yes, was hoping that it wouldn't come up on this forum but yes, "In the UK, the Coinage Offences Act 1936 prohibited the defacement of any current coins. This was repealed in its entirety by the Forgery and Counterfeiting Act 1981, thus removing the prohibition on coin defacement."

Spoilsport 


 .... but imagine the YouTube video of his execution on Tower Hill - now that WOULD go viral

Thanks. :-/

BillTodd, interesting suggestion, I think you would struggle getting a grip on such a small rim around the coin shell.

What would happen if it was tapped/hammered gently onto gradually increasing Mandrels so it sat on the end of each one like a cap. It would need tapping off and then moving to the next one. Or would it cause too much stress to the rim and rip it rather than stretch the material on the top/face of the coin.

Another thing, what about approaching it the other way. Could it be flattened I.e hammered, rolled or somehow increased in diameter and then bored and hollowed?

[BillTodd]

I think you would struggle getting a grip on such a small rim around the coin shell.

It doesn't grip on the rim it grips on the inside face . If you tried to expand the coin using just the rim it would certainly tear off.

Another thing, what about approaching it the other way. Could it be flattened I.e hammered, rolled or somehow increased in diameter and then bored and hollowed?

You could probably stretch it by doming it with a ball-pein hammer and a leather sand-bag , it might expand a bit when press flat again ???

[DavidA]

.. but imagine the YouTube video of his execution on Tower Hill - now that WOULD go viral..

Or you could get £250 if you sent it to You've been framed.

Dave.

[Joules]

Surely Chris would need to get another member stitched up for it to make "You've been Framed"

[R.G.Y.]

In the 1940's on our way to school past the dock railway. a halfpenny placed on the line would be the size of a penny after the train had past. No inscription remained though. This is only hearsay as the coinage act was still in force at the time.

[efrench]

Do it the same way a jeweler expands a ring...

[raynerd]

How is that? I thought they hammered it on a mandrel.

[Sid_Vicious]

What about an expanding mandrel? Think like an lathe chuck with inside jaws expanding out and stretching the outer ring.

[efrench]

They use a mandrel and a hide mallet. 

[raynerd]

They use a mandrel and a hide mallet.

But there isn't a central hole to hammer it onto.

What about an expanding mandrel? Think like an lathe chuck with inside jaws expanding out and stretching the outer ring.

Yes,I can imagine that but foresee it splitting the edges.

[efrench]

How about a set of short mandrels? 
Does the metal in the coin work harden or is it already hardened?

p.s. How about using a metal spinning technique on the lathe?

[j1312v]

Hi,

I was thinking about your problem  and I belive you need to make the cavity as close to the wall as you can, leaving a 0.02" wall thickness or less, then expand the coin with a mandrel  by just a tiny bit say 0.005-0.010''.
What you want is to fit another coin in that cavity so just file the sides of the other coin so it fits in to the cavity.

You may get away from expanding the coin if the you can manage the leave a 0.015" wall thickness and then file/machine the other coin to fit.
I reckon per side 0.015 can't be noticed by eye.

Best,

Joe

[raynerd]

Joe, I don't want to file or turn down the covered coin as this is what is know as a shell coin, which would only fit over a turned down matching coin or smaller coin. The expanded shell gaff coin, specifically fits over an none tampered with matching coin - does that make sense?

I did mention tapping it down on a mandrel but everyone said it'll split, which it probably will expanding if by the amount needed.

I'm still desperate to do this but I must admit I've not commited to any suggestions mentioned yet as I'm not totally clear that it would work or the method/equipment involved.

Chris

[R.G.Y.]

I have not tried this, but I think it would be better to expand the coin before boring it out. Placing it on lead (or annealed copper)will preserve the face wile striking the side to be bored. 
The coin will need to be struck near to the edge but not on it. R.G.Y.