4.58 gram 1984 Dollar

[markn]

My main concern with the image, is the small lip on the rim. This appears to be raised.
If this is the case, then the press pressure was good. The mint called this "squirting". Seen on a lot of coins today.

I agree that's exactly what it is.  But if the coin had been through a rimming machine it would have had high rims before being struck and this would easily explain the "squirting" as you call it or the "wire rim" as I call it.

[Fulvio]

... if the coin had been through a rimming machine...

"IF"? What planchets don't normally get rimmed?

[markn]

... if the coin had been through a rimming machine...

"IF"? What planchets don't normally get rimmed?

I am not sure all one cent coins were.  At least some 3d's didn't (I've seen genuine 3d and 1c clips without Blakesley effect).  Dodecagonal 50c coins don't.

[Fulvio]

I am not sure all one cent coins were.  At least some 3d's didn't

Well, ya live and learn! Thanks Mark. Clearly I meant to say round coins...

[robbiegal]

Several years ago the Mint had a display of coins that had gone through the start up process. Basically getting the press pressure right. I don't know if the display is still there or not, if it is, it is worth taking a look.

The scan of the dollar does not look consistent with a weak strike but more like uneven wear.
A near 30 year old coin that looks different, is thinner than normal does not mean it is an error.
The link to the $1 struck on a 10c planchet shows a reasonably good strike, so good strikes can occur on cu/ni planchets even though the presses are set up for al/br.

do you mean this one?

[markn]

I am not sure all one cent coins were.  At least some 3d's didn't

Well, ya live and learn! Thanks Mark. Clearly I meant to say round coins...

Don't take my word as gospel.  Just because I've seen clips without Blakesley doesn't mean they weren't rimmed intentionally.  Perhaps they missed the process accidentally.

Here's an example of a 1c that wasn't rimmed:

http://www.thepurplepenny.com/966,broadstrike-error-australian-1966-1-cent.html

But is it an error (uh flaw :dodgy:) because is wasn't rimmed?  Perhaps the larger diameter meant it didn't sit in the collar and was thus struck out of collar?

Now that I think of it I don't believe I've ever seen a rimmed 1c blank.

[Fulvio]

flaw

Yup, flaw. And a lovely one at that... you open to offers?

[markn]

Yup, flaw. And a lovely one at that... you open to offers?

There's an offer button on the page.  Offer away, I am sure PPH will be kind.

[robbiegal]

I sold one like that a million years ago on ebay and it went for far more that that asking price
they are tremendously cute those mis-struck 1 c pieces
and fairly uncommon as well

[Cobwebs]

Thanks PPH & Robbiegal that is what I remember. When I was at the Mint I was with an employee and we chatted several minutes on the subject of weak strikes. I thought there was a coin there that had more than 140 tonnes pressure but obviously I was mistaken. In our chat he told me that over pressure caused squirting so the pressure was backed off. On circulation coins it occurs at times due to mass production, they aim for good die life and good strikes.

markn - back to the inconsistent weak strike, 1st the definition.
"Weak strike - A coin exhibiting an incomplete strike (not fully formed) all over, or a partial incomplete strike of the design. Caused by insufficient pressure to push metal into all the nooks and crannies of the die, improper die spacing, or the planchet being thinner than normal."

On a weak strike the centre of the coin will be bolder than the outside

The inconsistencies I am talking about are.
There appears to be a strip across the Obverse from ZA in elizabeth to ST in australia which is bold, the whole legend should be more even.
On the Reverse the middle roo has eyes this is near the rim, yet the 2nd roo behind the 1 does not, this is closer to the centre.
There appears to be a depression from the base of the 1 across to the A in dollar.
The R in dollar appears to be too bold.
Then there is the wire rim, to me that suggests a good or reasonably good strike. Will it have weak spots, I would say yes, but this doesn't mean it is a weak strike.
It appears to be something else that has happened to your coin.

A better image comparison would be another coin that is a weak strike.

Re; the thin planchet, it obviously is, my comment was a poorly worded one, wanting to say that thin planchets don't always mean you get a weak strike.

If it is a cu/ni planchet, the only ones I'm aware of are the Tonga (1975 to 1990) 23.6mm, 5.69gms, for their 10 seniti, cu/ni.
To the best of my knowledge the mint only produce blanks for overseas in the early 70s, but I'm not sure which type.


Fulvio - It's an error.
Flaws occur on the die then transferred to the coin.

Blanks; 1c where rimmed, I have or had both clipped blanks and planchets. The 50c has a very thin rim for its size, the smaller 20c is larger and needs to be rolled.

markn - I hope the broadstrike isn't the coin you are referring to as not being rimmed as I would disagree.

[Fulvio]

Fulvio - It's an error.
Flaws occur on the die then transferred to the coin.

Meh. Semantics. Call it a Fault then, if you want to use Flaw for dies. Regardless, its not like a consistent Error as we know them.

[markn]

markn - back to the inconsistent weak strike, 1st the definition.
"Weak strike - A coin exhibiting an incomplete strike (not fully formed) all over, or a partial incomplete strike of the design. Caused by insufficient pressure to push metal into all the nooks and crannies of the die, improper die spacing, or the planchet being thinner than normal."

On a weak strike the centre of the coin will be bolder than the outside

That generalisation (putting aside issues of die concavity and relief of the design being struck) might be right if we were talking simply about a press with low pressure but this is clearly a different situation.  As I have already said, this coin is clearly fully struck around the rims and in some of the design.  If the coin was thin when it was edges the formed rims could easily be high enough to cause a localised area of high striking pressure.  If you have some exposure to presses you'd understand that pressure varies across the surface of the piece being struck and pressure varies as the amount of plastic deformation increases.  And that pressure is a function of force and area.  Higher than usual rims (from the thin planchet) means more deformation at the outside of the coin and more pressure resulting in a coin that is not fully struck in other areas.  Not to mention a 4.6 gram planchet could simply not have enough metal to fill the design completely.

The inconsistencies I am talking about are.
There appears to be a strip across the Obverse from ZA in elizabeth to ST in australia which is bold, the whole legend should be more even.
On the Reverse the middle roo has eyes this is near the rim, yet the 2nd roo behind the 1 does not, this is closer to the centre.
There appears to be a depression from the base of the 1 across to the A in dollar.
The R in dollar appears to be too bold.

Assuming that this is a regular low pressure strike which it isn't.  It's less than half the weight of a dollar coin so we're talking about a completely different set of circumstances to those shown in the 50c die pressure images shown above.

Then there is the wire rim, to me that suggests a good or reasonably good strike. Will it have weak spots, I would say yes, but this doesn't mean it is a weak strike.
It appears to be something else that has happened to your coin.

You're inventing complexity.  It's an undersized and underweight planchet.  It was rimmed.  The high point of the planchet (the rims) were struck properly and probably provided enough resistance to trip the pressure limit on the press.  Not to mention the fact that there may simply not be enough metal to fill the high points of high relief on the die.

A better image comparison would be another coin that is a weak strike.

No, it wouldn't.  This is completely different to a regular weak strike.  To be honest I am gob-smacked that you cannot see the similarities between this coin and the $1 on a 10c planchet.  In hand they are REMARKABLY similar.  In fact if I didn't know one weighed 1g less than the other I'd swear they were the same error.

markn - I hope the broadstrike isn't the coin you are referring to as not being rimmed as I would disagree.

What evidence to you see of that broadstrike having been rimmed?

[trout]

@Cobwebs
There is absolutely NO doubt in my mind that this coin is  genuine.
The origin of the substitute planchet is the most interesting part of this discovery as far as I am concerned :ok:

[Fulvio]

The origin of the substitute planchet is the most interesting part of this discovery as far as I am concerned :ok:

I'd go along with that. What IS the planchet, and was it made here for a foreign client, or were our planchets purchased from a foreign supplier who also made it for someone else?

Fascinating detective story. Can't wait to get to the last chapter.

[trout]

The origin of the substitute planchet is the most interesting part of this discovery as far as I am concerned :ok:

I'd go along with that. What IS the planchet, and was it made here for a foreign client, or were our planchets purchased from a foreign supplier who also made it for someone else?

Fascinating detective story. Can't wait to get to the last chapter.

You and me both mate, my bum is getting sore sitting on the edge of my seat waiting for a definitive answer :angel: