1965 kennedy 11.65 grams
bigMACnoCheese
Posts: 110
Hello,
first time posting.
I have a question on a 1965 SMS Kennedy
It comes up as 11.65 grams and doesn't show a copper core band.
Nowhere can I find math info to calculate the core weight to see if it is greater that the .209% silver.
But this is what I have come up with.
Can someone check my math to see if I am coming up right?
This is based off of calculating a pre 1965 90% silver then running the numbers against a 40% for the clad and the core and it seems the core would have somewhere around 32% silver.
Notes on my calculations, the diameter and thickness are trimmed to account for the reeding and the obverse and reverse depression of the strike, since I am making the assumtion that the stated dimensions of the 50 cent piece is post strike and not the planc. size.
Square of diameter X thickness X 0.785 X density of alloy = weight of a circle. (lbs column is the result)
diameter in inches, thickness in inches, density cuin, lbs, grams
1.1811, 0.0675, 0.323, 0.023886561 = 10.83476174 for pure copper at a known volume
1.1811, 0.0675, 0.378, 0.027953932 = 12.67969021 for pure silver at a known volume
running with these known weights I get
0.1000 1.083476174 copper
0.9000 11.41172119 silver
12.49519736 1964 weight
now for calculating the 1965 based off these numbers.
clad, core, clad grams, core grams, totals, % of each metal
0.20, 0.6750, 0.541738087, 5.485098131 = 6.026836218, 0.517171899% copper
0.80, 0.3250, 2.535938042, 3.090674489 = 5.626612531, 0.482828101% silver
0.2500, 0.7500, 1.538838065, 11.65344875 total grams
the .25 and .75 are assumtions to the ratio of clad to core in volume, which equals 11.49 grams when core silver is set to .209 and core copper is set to .791
1.53 grams is the individual clad layers
Even if I move the clad layer up from 25% to 33%, which I can't believe the clad layers would be 33% of the volume of the coin, the total weight still only reaches 11.58 grams.
Anyone care to shoot me in the head and tell me where I am wrong..
or is 48/52 close enough to 40/60 for government work? (just joking)
sorry for the commas, but tables don't post.
thanks
John
first time posting.
I have a question on a 1965 SMS Kennedy
It comes up as 11.65 grams and doesn't show a copper core band.
Nowhere can I find math info to calculate the core weight to see if it is greater that the .209% silver.
But this is what I have come up with.
Can someone check my math to see if I am coming up right?
This is based off of calculating a pre 1965 90% silver then running the numbers against a 40% for the clad and the core and it seems the core would have somewhere around 32% silver.
Notes on my calculations, the diameter and thickness are trimmed to account for the reeding and the obverse and reverse depression of the strike, since I am making the assumtion that the stated dimensions of the 50 cent piece is post strike and not the planc. size.
Square of diameter X thickness X 0.785 X density of alloy = weight of a circle. (lbs column is the result)
diameter in inches, thickness in inches, density cuin, lbs, grams
1.1811, 0.0675, 0.323, 0.023886561 = 10.83476174 for pure copper at a known volume
1.1811, 0.0675, 0.378, 0.027953932 = 12.67969021 for pure silver at a known volume
running with these known weights I get
0.1000 1.083476174 copper
0.9000 11.41172119 silver
12.49519736 1964 weight
now for calculating the 1965 based off these numbers.
clad, core, clad grams, core grams, totals, % of each metal
0.20, 0.6750, 0.541738087, 5.485098131 = 6.026836218, 0.517171899% copper
0.80, 0.3250, 2.535938042, 3.090674489 = 5.626612531, 0.482828101% silver
0.2500, 0.7500, 1.538838065, 11.65344875 total grams
the .25 and .75 are assumtions to the ratio of clad to core in volume, which equals 11.49 grams when core silver is set to .209 and core copper is set to .791
1.53 grams is the individual clad layers
Even if I move the clad layer up from 25% to 33%, which I can't believe the clad layers would be 33% of the volume of the coin, the total weight still only reaches 11.58 grams.
Anyone care to shoot me in the head and tell me where I am wrong..
or is 48/52 close enough to 40/60 for government work? (just joking)
sorry for the commas, but tables don't post.
thanks
John
0
Comments
Russ, NCNE
San Diego, CA
<< <i>
Square of diameter X thickness X 0.785 X density of alloy = weight of a circle. (lbs column is the result)
diameter in inches, thickness in inches, density cuin, lbs, grams
1.1811, 0.0675, 0.323, 0.023886561 = 10.83476174 for pure copper at a known volume
1.1811, 0.0675, 0.378, 0.027953932 = 12.67969021 for pure silver at a known volume
running with these known weights I get
0.1000 1.083476174 copper
0.9000 11.41172119 silver
12.49519736 1964 weight
now for calculating the 1965 based off these numbers.
clad, core, clad grams, core grams, totals, % of each metal
0.20, 0.6750, 0.541738087, 5.485098131 = 6.026836218, 0.517171899% copper
0.80, 0.3250, 2.535938042, 3.090674489 = 5.626612531, 0.482828101% silver
0.2500, 0.7500, 1.538838065, 11.65344875 total grams
the .25 and .75 are assumtions to the ratio of clad to core in volume, which equals 11.49 grams when core silver is set to .209 and core copper is set to .791
1.53 grams is the individual clad layers
Even if I move the clad layer up from 25% to 33%, which I can't believe the clad layers would be 33% of the volume of the coin, the total weight still only reaches 11.58 grams.
>>
This is a little too heavy I believe. The core on these is very difficult to see on
some silver clads.
Without more info my best guess is that the core was a little too thick or the blanking press was worn.
Let's see what the experts think.
I hope that doesn't mean it was a stupid question.
<< <i>I hope that doesn't mean it was a stupid question. >>
There are no stupid questions, only stupid people, and they're all over in the open forum.
Russ, NCNE
San Diego, CA
And I think something is wrong with the calculations that gave you your densities of copper and silver. Density of copper in 8.9 grams per cubic centimeter or about .33 pounds per cubic inch. Silver in 10.5 grams per cc or .38 pounds per cubic inch.
This formula strikes me as odd as well
<< <i>Square of diameter X thickness X 0.785 X density of alloy = weight of a circle. (lbs column is the result) >>
I use Pi X radius squared X thickness X Density = Weight of cylinder.
Density of the core material is (8.9 X .785) + (10.5 X .215) = 9.24
Density of clad layers is (8.9 X .2) + (10.5 X .8) = 10.18
Weight of core = thickness core ((Pi X (1.53cm)^2) X 9.24) or thickness(core) X 67.95
Weight of clad layers = thickness clad (( Pi X (1.53cm)^2) X 10.18) or thickness(clad) X 74.87
thickness(core) + thickness(clad) = .16 cm (I am assuming that the 40% clad planchets are the same thickness as the 90% planchets.
running a few test it works out that if the core is .07 cm (.7mm) thick and the total thickness of the clad layers is .09 cm (So each layer is .045 cm or .45mm) the weight works out to 11.49 grams.
This makes the weight of the core 4.76 grams and the clad layers weigh 6.74 grams or each layer weighs 3.37 grams.
<< <i>
Russ, NCNE >>
WELCOME BACK RUSS!!!!!!!!!!
Hell, I don't need to exercise.....I get enough just pushing my luck.
11.5......grams.........
edited to add...................
There are tolerances in the weights that typically run slightly under 10%. Not sure exactly what they are for 40% silver clad halves.
Sight alone is not enough to determine anything....it's a first step.
Ike Specialist
Finest Toned Ike I've Ever Seen, been looking since 1986
More and more these days I find myself pondering how to reconcile my net income with my gross habits." - John Nelson.
Also, if trying to do this mathematically, remember that you can only get an accurate measurement of the thickness by measuring a type one blank. Struck coins get thicker at the rim or on the head than the blank was, and thinner at opposing fields because the metal that got pushed up into the head had to come from somewhere.
Tom D.
using your numbers
"running a few test it works out that if the core is .07 cm (.7mm) thick and the total thickness of the clad layers is .09 cm (So each layer is .045 cm or .45mm) the weight works out to 11.49 grams.
This makes the weight of the core 4.76 grams and the clad layers weigh 6.74 grams or each layer weighs 3.37 grams. "
this provides
2.3714 total silver grams
9.1286 total copper grams
or
silver content of 20.6%
copper content of 79.37% this would be far under 40% silver
So I believe your clad layer weight (assumption on thickness) is too much.
in http://www.minterrornews.com/ issue 15 there is an article on $.50 40% silver that states a clad layer is approximately 2 grams.
Interesting........
But:::::::
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If you increase the thickness of the core to .11cm then you get a core weight of 7.47 grams and a (total) clad layer weight of 3.74 grams . You get a total silver weight of 4.6 grams, which when compared to the specified weight of 11.5 grams gives you 40% silver. The problem is as you increase the thickness of the core the overall weight of the coin declines. With a core of .11 cm the actual weight of the coin drops to just 11.21 grams. Still within the mint tolerance but it is a bit extreme.
I think where the error comes from is the assumption that the 40% clad planchet was the same thickness as the 90% silver planchet.
Ran some more numbers and you have to make the planchet thicker .165 cm, and increase the core thickness to .12 cm
That gives a core weight of 8.15 grams and (total) clad layer weight of 3.37 grams (Two layers each .0225 cm thick, each weighing 1.685 grams) for a total weight of 11.52 grams, total silver weight would be 4.45 grams and the overall percentage weight of silver would be 39%
my point exactly, except 1
hold the core and thickness constant and increase the silver content of the core. The weight goes up.
My belief in that the silver content of the core is greater than .791 to .201 for copper
.201 for silver
.791 for copper
If the silver fineness of the core was a little higher you could get it to work with the thinner planchet, but as I have shown you can get it to work with the official finenesses and the slightly thicker planchet. Since there has never been any other evidence that the content was anything other than what the official specifications call for why do you think it would be otherwise?
<< <i><smile>
my point exactly, except 1
hold the core and thickness constant and increase the silver content of the core. The weight goes up.
My belief in that the silver content of the core is greater than .791 to .201 for copper >>
Then have an assay done on the coin and melt it.
Or accept the simple explanation that the piece is slightly off-weight, though still within mint tolerance.
TD
good density test if you can weight it in water. Just assume the cladding is normal
and look for a discrepancy in density.
Ed. S.
(EJS)
I'm just trying to figure it out.
I have been given some great things to think about.
Conder101
thanks for your information on the ratio on the core. I have corrected my calculations using your numbers, but I still see the core being heavier than it should be.
Please look at the attached spreadsheet.
http://www.yousendit.com/transfer.php?action=download&ufid=58A007C867012855
Clad king, I did what you suggested, not by water though, even though I am sure that would be more accurate.
but by ignoring the clad layer, or making assumptions to the weight of those to the coin, I see a density difference.
If anyone cares to review my spreadsheet and provide additional insight to where I am wrong.
I guess the only way would to really know is take one and put it on the old gas grill heat it up real nice and hot and throw in on a big ice cube and see if I can get the clad layer to pop off. (just joking here)
Thanks to all, except the guy who wants me to melt it.
John
It does look interesting that you figured 33% for yours if so.
Link to above spreadsheet.
results are after 4 tests
SG = 9.7 for the coin
thats a 50/50 silver/copper