I have read that die adjustment strike coins are produced during the setting up adjustment of the dies and or coin presses. The striking pressure is started low and gradually wound up until sufficient pressure is present to make the coin metal flow correctly into the design elements of both the obverse and reverse dies. I believe it is done this way as starting with too high a striking pressure could damage the dies or collar. These coins would also be produced if there was a press failure during striking and the striking pressure was reduced for any reason but it is not possible to prove which of these circumstances a coin has been struck under. However die adjustment strike coins should not make it out of the mint in normal circumstances as the person setting up the press is watching them being struck. For a coin to be a die adjustment strike the strike weakness should be equal and regular on both sides of the coin. I reckon any edge milling should also be weak or not there at all. The coin should also be the correct weight for a normally struck coin of it's type. The central part of the design will generally be struck up first.
Here is a five cent coin to get the thread started.
(http://i243.photobucket.com/albums/ff235/Blunderstruck/5centdieadjustrev.jpg)
(http://i243.photobucket.com/albums/ff235/Blunderstruck/5centdieadjustobv.jpg)
Superb coin!
I rarely see these coins. A friend of mine has a $2. I'll get an image probably on Tuesday. Really interested in seeing if others have examples of these in Australian coinage. I see them slabbed a bit with PCGS in US coinage.
You can just make out the portrait on this $2. Bought as a blank planchet.
(http://www.australian-threepence.com/images/die-adjustment-strike-1.jpg)
Here is the $2 I mentioned before.
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[attachment=209]
Ooooh nice.
Picked this one up last week. I am a sucker for a 64 penny.
(http://www.australian-threepence.com/images/australia-1964-1d-die-adjustment.jpg)
Before the RAM's big renovation they had a display showing the effect of increasing the strike pressure from low to normal for a 50 cent piece. I understand from RAM staff they 50 cent pieces are the hardest to get a good strike. Did anyone see it? Is it still there? I have not visited the RAM since the renovation.
Had this one penny for some time.
(http://i243.photobucket.com/albums/ff235/Blunderstruck/DCP_0214a.jpg)
(http://i243.photobucket.com/albums/ff235/Blunderstruck/DCP_0213a.jpg)
Quote from: 'caivel' pid='1133' dateline='1349177259'Before the RAM's big renovation they had a display showing the effect of increasing the strike pressure from low to normal for a 50 cent piece. I understand from RAM staff they 50 cent pieces are the hardest to get a good strike. Did anyone see it? Is it still there? I have not visited the RAM since the renovation.
These pics were taken in March 2011, the display was there then.
(http://www.australian-threepence.com/images/strike-pressure-50c.jpg)
Cool :P
The RAM should make up sets. Would sell very well I suspect.
The error display was still there during the Enlighten Festival this year. I haven't been back since so I am not sure if they still have it up.
I have a large number of photos from that event and the error displays. I'm just not sure what memory card they are on. When I find it, I'll make a topic showing them.
I got to opening the CAB yearbook today and on page 39 there is a halfpenny which Ian McConnelly cant seem to identify. I really wouldnt have much of a clue but it looks like a die adjustment strike to me. Does anyone else think this?
Yes it is enworb.
Found this one a few days ago, i had put it away years ago & forgotten i even owned it, i'd have hundreds of coins i've forgotten i own LOL.
(http://i389.photobucket.com/albums/oo339/appeangel07_photos/29-9-08/new%20coin%20album/007-2.jpg)
(http://i389.photobucket.com/albums/oo339/appeangel07_photos/29-9-08/new%20coin%20album/008-1.jpg)
What a nice coin to foget about and refind.
Those are the best coins because they don't cost you anything.
Lovely coin- turns a common date into a "One Off"