1979 Kennedy Half Struck On Susan B Anthony Dollar / SBA Stock?

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Author	Replies: 9 / Views: 4,307
jack jeckel Pillar of the Community United States 5208 Posts	Posted 10/29/2017 5:45 pm So I have found more than a few 1971D Kennedy half dollars struck on quarter stock weighing 8.8 grams. Today I found another one as well as a 1979 Kennedy half that had the same "ring" to it. Ont he scale it comes in at 9.5 grams so I know it is not on quarter stock but it got me thinking what other coins were being minted at the same time and what stock it could be. Well the SBA dollars were out at the same time. Are there any math wizards out there want to calculate if a normal quarter weighs 5.67 grams and a half on quarter stock weighs 8.8 grams then if a SBA weighs 8.1 grams what should a half on SBA stock weigh? I came up with 12.57 grams so if that is the case then what is up with this one. Edited by jack jeckel 10/29/2017 5:58 pm Report this Post to the Staff

Mark1959 Pillar of the Community 7234 Posts	Posted 10/29/2017 6:41 pm Stamping half rounds out of SBA stock? Does that really happen? And when do they find that out? After being stamped the upsetting mill produces the semi rim on the planchet. Report this Post to the Staff
Earle42 Bedrock of the Community United States 10038 Posts	Posted 10/29/2017 8:53 pm I think a ratio would suffice: SBA is 8.1 grams per 26.5 mm diameter Alleged half is X grams per 30.6 mm So set them equal to each other: X/30.6 = 8.1/26.5 Solve for X by multiplying both sides by 30.6 (left side cancels out) x = (8.1 / 26.5) / 30.6 x = 9.35 grams It may be your piece is within tolerance levels. Now I need to check the light sounding ones I have sometime. Since the thickness differences is 2.00mm for SBA and 2.15 for JFK, Halves, the thicknesses may not be a good indicator as this small of a difference may well be within acceptable tolerance levels. You may have solved the mystery on these lighter halves! How much squash could a Sasquatch squash if a Sasquatch would squash squash? Download and read: Grading the graders Costly TPG ineptitude and No FG Kennedy halves https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2 Report this Post to the Staff
coop Bedrock of the Community United States 62064 Posts	Posted 10/29/2017 9:34 pm Here is a gauge I found some time ago: It might be what you are wanting? Report this Post to the Staff
Halo1st Pillar of the Community United States 2775 Posts	Posted 10/29/2017 9:48 pm More food for thought. Thanks, Doug. https://www.coinworld.com/news/us-c...-wr.all.html Report this Post to the Staff
Earle42 Bedrock of the Community United States 10038 Posts	Posted 10/29/2017 9:59 pm The above website has the same process I used for calculating the mass. I got the weights from online and the diameters. So I wonder why there is a discrepancy in the chart and the calculated result? The calculation is 9.35 and the chart says 10.81 However, the website does say: Quote: The weight of the actual coin may deviate up to 0.15 gram from the expected weight. Deviations greater than 0.2 gram in either direction probably mean you've got a rolled-thin error instead of a wrong stock error. So according to the website, the deviation of calculated 9.35g + .15g would be 9.5 = the weight of this half dollar. Unlesss someone can point out an error in the measurements I used, or the final calculation, I am wondering how the makers of that chart got their numbers? Did I miss something? How much squash could a Sasquatch squash if a Sasquatch would squash squash? Download and read: Grading the graders Costly TPG ineptitude and No FG Kennedy halves https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2 Report this Post to the Staff
jack jeckel Pillar of the Community United States 5208 Posts	Posted 10/29/2017 11:29 pm I found this thread http://goccf.com/t/234073#234073 I also have a at least 10 halves that are all 10.5 grams over several years. When you have a few examples of the same year and mint I think it lead credence to a legit error. Report this Post to the Staff
Earle42 Bedrock of the Community United States 10038 Posts	Posted 10/30/2017 4:57 pm Found my mistake - and should have seen it before. For some reason my cloudy mind was only taking the diameter and not the area for each coin into consideration. The thickness is not a factor since all that is allegedly involved are SBA thicknesses for both. The calculation is still a ratio (as the website confers). The specs of the SBA are: 8.1 g Diameter: 26.5 mm - so radius is 13.25 Area of a SBA (circle): Area = pi; * r^2 = 3.14 * 13.25mm^2 = 551.55 mm^2 For the half: X = weight to be calculated Diameter = 30.6 => radius is 15.3 Area = 3.14 * 15.3^2 = 735.42 mm^2 The ratio (and per the website also) is: weight of SBA = expected weight of wrong stock half area of SBA ............area of half dollar (Had to add periods b/c the forum does not support strings of empty spaces) ... 8.1 g .... = .....X..... ....551.55.....735.42 .0015 = X / 735.42 .0015 * 735.42 = X 10.8 = X This is closer to the chart's 10.5, but is still off. The website says the error can by .15, however this still puts the calculation at 10.65 The chart, the math (as conferred by the website), and the actual picture of this coin weighing 9.5 g all disagree. Since the math and the reasoning behind it are sound, I would go think a half on SAB stock would be 10.65 to 10.95 using the website's tolerances. The website says a difference of .2 grams is likely a rolled thin error. If someone sees a mistake in the application of the numbers I did, please let me know. But I think this time it is correct. Do we have the source of that chart coop? Why don't the chart and the math agree? So just how does a half dollar get all the way down to 9.5 as in jack jeckel's pics? How much squash could a Sasquatch squash if a Sasquatch would squash squash? Download and read: Grading the graders Costly TPG ineptitude and No FG Kennedy halves https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2 Report this Post to the Staff
Coinfrog Bedrock of the Community United States 94367 Posts	Posted 10/30/2017 5:06 pm I was told there would be no math. Report this Post to the Staff
Earle42 Bedrock of the Community United States 10038 Posts	Posted 10/30/2017 5:10 pm I am ashamed to admit it after my blunder, but I was a math teacher for years. Oh well - humble pie time. How much squash could a Sasquatch squash if a Sasquatch would squash squash? Download and read: Grading the graders Costly TPG ineptitude and No FG Kennedy halves https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2 Report this Post to the Staff
	Replies: 9 / Views: 4,307

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1979 Kennedy Half Struck On SBA Stock?