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 Replies: 15 / Views: 3,413 |
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Pillar of the Community
Australia
4411 Posts |
Found a 50c today with a distinct crack right around the edge. It sounds very tinny when dropped. I'm fairly sure its split right through so I've been trying to split it into two halves.
Ive tried dropping it and heating and the cooling it very quickly but that hasnt worked.
I there another method that people can think of?
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Pillar of the Community
Australia
908 Posts |
Would be good to see a picture of it Matt
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Bedrock of the Community
Australia
21788 Posts |
This type of error is common enough. It comes about when the strip from which the blanks are are cut, laminates.
I don't know what causes the strip to laminate, but I can guess at two different hypotheses:
1. The strip is rolled then folded, then rolled again, much like commercial puff pastry. Intuitively I do not think that strip for coin blanks is rolled in this way.
2. The strip is rolled from a billet, and the temperature of the billet is outside of specification during the rolling process. When the strip is rolled to thickness, there must be internal shear within the billet, that would cause a layering effect.
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Pillar of the Community
 Australia
4411 Posts |
Theres really no point posting pictures until it splits. It is simply a 1980 50c coin with a crack right around the edge. I think your second hypothesis sounds the most plausible sel. Thanks
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Valued Member
Australia
318 Posts |
I've got a couple of 1976 50c coins that have a fault through the centre - you can see the weakness through the middle when holding edge-on. I've tried boiling water, then freezer, then boiling water - but no luck......
Maybe a whack with a (covered) hammer to one side of the edge may do it, but that may cause damage to the coin itself, that's why I haven't tried this. If done in the right place it may shear off along the plane of the weakness.
Am curious to know if anyone's successfully split a coin.....
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Pillar of the Community
Australia
674 Posts |
I remember a bloke who split an atom- didn't turn out all that well.!  |
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Moderator
 Australia
16829 Posts |
Quote:
Am curious to know if anyone's successfully split a coin..... I've heard anecdotal stories of kids back in predecimal days, who whiled away their spare time throwing the sixpence they'd been given by their mum to spend on the ground at an angle. If they got lucky and if they threw it just right, the coin would split clean in half and, hey presto, they'd now have two sixpences to spend - provided the storekeeper didn't catch them. As I understood the story, you want to flick it into the ground at a shallow angle - almost as if you were skipping it across water. This story is also why I'll never, ever pay the big bucks some folks pay for "split planchet errors". I fear that they're too easy to synthesize. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
1119 Posts |
differences in hot and cold will be the best option to seperate the layers without using tools
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Pillar of the Community
1119 Posts |
maybe try freezing the coin when its frozen stick a hose clamp around one half of the split if possible and apply heat, if it works be careful a hot coin might jump up at ya
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Bedrock of the Community
Australia
21788 Posts |
erkle: Perhaps you already know.
Splitting by frost shattering is the way to go, provided the split has developed over the whole area of the coin.
The method relies on the fact that water has it's maximum density at 4 deg. Celcius. It then expands as it freezes.
That is why mountains in the European Alps, where rock is exposed, have sharp edges. eg. Mount Matterhorn. This the result of natural frost shattering, where water gets into crevices, freezes and expands, and cleaves off large pieces of rock.
enworb:
Method:
1. Put the coin in a glass of water, and chill the water to 4 deg. Celcius. You will need an accurate thermometer to do this.
2. Put the glass containing the water into the coldest part of the freezer compartment of your fridge. The water will expand as it freezes, and hopefully cleave the two halves apart, without leaving a mark on your coin.
One problem: Your wife may think you are trying to be some sort of mad scientist!
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Valued Member
Australia
490 Posts |
I think the reasons for this are that the slag (the impurities in the metal) are not taken off and somehow mixed into sheet before stamping. I have several of these, some fully split, some still together, but they all have markings in the splits which look like slag to me (have a mate who has a steel factory so have seen the slag first hand...)
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Pillar of the Community
1119 Posts |
was told this by a steel works worker, when making rolls they sometimes run out of steel, when it happens they quickly place the next section in and lay it over the top of the previous section to then be rolled to the same thickness.
maybe when this does not happen quick enough and the metal cools below a certain level the 2 sections do not meld as they should? which then creates this type of metal flaw.
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Pillar of the Community
Australia
7096 Posts |
Quote:
Found a 50c today with a distinct crack right around the edge. It sounds very tinny when dropped. I'm fairly sure its split right through so I've been trying to split it into two halves.
Ive tried dropping it and heating and the cooling it very quickly but that hasnt worked.
I there another method that people can think of?
Why not simply leave the coin as it is  If you split it it would simply be a PMD coin. |
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Pillar of the Community
Australia
4411 Posts |
I need to clarify; I would not say the coin has a split but it definitely has a large crack through the metal. I can not see into the gap. As it is it is worth 50c and no more guaranteed. It is nothing special unless its split open more or cracked into two pieces. I'm going to give the freezing idea a go overnight.
Edited by enworb
12/20/2012 11:14 pm
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Pillar of the Community
1119 Posts |
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Pillar of the Community
Australia
4411 Posts |
Thanks for the tip erkle but I actually gave up after a few days of freezing then dropping in hot water etc. I dont think it was split enough to start with. I tried throwing it as hard as I could against a brick wall and even that didnt work, just mutilated it. I've released it back into the pond.
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Replies: 15 / Views: 3,413 |
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Posted 12/19/2012 11:56 pm
