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Posted

Could be they drilled a small hole in the die to limit the crack. It is a well known technique to drill a small hole at the end of a crack as it reduces the stress at the tip and so makes it less likely the crack will propagate further.

  • Like 1
Posted
56 minutes ago, Paddy said:

Could be they drilled a small hole in the die to limit the crack. It is a well known technique to drill a small hole at the end of a crack as it reduces the stress at the tip and so makes it less likely the crack will propagate further.

Interesting, do you think the images show that progression? A crack formed, two holes drilled and then the die deteriorated further to show the pronounced crack we see in the first image.

Posted (edited)

I just noticed the following; 

https://aboutfarthings.co.uk/catalogue/farthing-varieties/

"Obverse 2e Die Fault resembles colon between 8 & 5 in Datal Figures (Image shows early stage of flaw, advanced stage can be seen in the enlarged image"

I saw a coin listed as having a colon and when looking at other 1851 farthings I noticed the example with the crack, aboutfarthings.co.uk has it spot on.

Edited by absence of uniformity
Posted
10 hours ago, absence of uniformity said:

Interesting, do you think the images show that progression? A crack formed, two holes drilled and then the die deteriorated further to show the pronounced crack we see in the first image.

I cannot say definitely that is the case, but it certainly seems a possibility. I suppose the other way would be if parts of the die were fragile and broke off around the nascent crack, but I don't think the metal used in the dies was usually that brittle.

Posted (edited)
2 hours ago, Paddy said:

I cannot say definitely that is the case, but it certainly seems a possibility. I suppose the other way would be if parts of the die were fragile and broke off around the nascent crack, but I don't think the metal used in the dies was usually that brittle.

I engraved some coin dies in 1/12 scale for Dolls house money. I used mild steel and after striking 20 coins the mild steel dies deformed. I dont know but would imagine real coin dies are tempered to a certain degree making them less likely to deform like the dies I made. I tried striking gold, silver, bronze and copper all soft metals compared to mild steel, the fact my dies were not tempered they deformed. I quickly understood a highly polished die and more force when striking the dies produced much higher quality strikes. When I try it again I will anneal 01 tool steel engrave my obverse and reverse then temper them in order to harden the metal so I can strike more than 20 coins. There will be a trade off between a soft of a die that deforms with subsequent strikes and tempering the metal too hard the dies crack rather than deform.

If a metal cracks rather than deforms it suggests it is tempered or work hardened and with each subsequent strike the metal is probably hardening itself also. At a guess I would think a pair dies slowly harden over the working life of a pair of dies which may lead to crack dies??

I made a steel tube/collar inserted the bottom die into the collar then placed my metal blank into the collar then presented the other die and struck it with a hammer. Initially I was getting weak strikes, then started hitting it harder which produced much nicer strikes but ultimately deformed the dies.

637824137_10164847320746514_1972425868737022780_n.jpg

638247753_10164847320741514_4944973904580405969_n.jpg

638739896_10164847311441514_699585515610293094_n.jpg

639136732_10164847311701514_3905495404046990235_n.jpg

639825484_10164847311656514_5561591360269339241_n.jpg

Edited by absence of uniformity
  • Like 1
Posted
18 minutes ago, absence of uniformity said:

I engraved some coin dies in 1/12 scale for Dolls house money. I used mild steel and after striking 20 coins the mild steel dies deformed. I dont know but would imagine real coin dies are tempered to a certain degree making them less likely to deform like the dies I made. I tried striking gold, silver, bronze and copper all soft metals compared to mild steel, the fact my dies were not tempered they deformed. I quickly understood a highly polished die and more force when striking the dies produced much higher quality strikes. When I try it again I will anneal 01 tool steel engrave my obverse and reverse then temper them in order to harden the metal so I can strike more than 20 coins. There will be a trade off between a soft of a die that deforms with subsequent strikes and tempering the metal too hard the dies crack rather than deform.

If a metal cracks rather than deforms it suggests it is tempered or work hardened and with each subsequent strike the metal is probably hardening itself also. At a guess I would think a pair dies slowly harden over the working life of a pair of dies which may lead to crack dies??

I made a steel tube/collar inserted the bottom die into the collar then placed my metal blank into the collar then presented the other die and struck it with a hammer. Initially I was getting weak strikes, then started hitting it harder which produced much nicer strikes but ultimately deformed the dies.

637824137_10164847320746514_1972425868737022780_n.jpg

638247753_10164847320741514_4944973904580405969_n.jpg

638739896_10164847311441514_699585515610293094_n.jpg

639136732_10164847311701514_3905495404046990235_n.jpg

639825484_10164847311656514_5561591360269339241_n.jpg

What great fun! That is really rather clever, nice job!

Jerry

Posted
19 minutes ago, jelida said:

What great fun! That is really rather clever, nice job!

Jerry

Thanks ! I started out with intentions to try and engrave reverse and obverse design of a penny, I quickly gave up on that. Impossible. I have a pantograph that I can mill metal but struggled with that because the dies are 4mm diameter even with a 6:1 reduction. In the end I engraved the designs freehand using a loupe, it was tricky. For a normal size coin I could print a guide/stencil on the 3d printer and using the pantograph mill the design into a steel die then temper it.

The more simple designs of hammered coins I could make something that resembles the real thing. Although I have no intentions of forging any coins.

Posted (edited)

Here is the pair of dies and the coin I struck with them. This was the largest I made and because I spent a while engraving them I was more gentle with the hammer. The image shows the dies and the coin made using them.

20260704_125237_optimized_500 (2).jpg

637824137_10164847320746514_1972425868737022780_n.jpg

638247753_10164847320741514_4944973904580405969_n.jpg

Edited by absence of uniformity
  • Like 1
Posted (edited)

Those little pieces are stunning, I’m so impressed! 🙌

Also, aboutfarthings was very active member on here…last time I contacted him, he’d been swamped with work.

Around 25 years ago I used to make little refectory tables from dendro-dated Tudor oak. Great fun!

And @Paddy really great point re drilling the die…not sure what Colin (from AF) said, I haven’t looked at @absence of uniformity’s link, yet?

Edited by Coinery
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