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Accuracy of new coin scale
Prethen
Posts: 3,454 ✭✭✭
I just acquired a new coin scale that supposedly has an accuracy of 0.01g. It didn't come with a calibration weight so I have none, however, the scale will zero itself out on turning on. Not sure if this means much.
I placed a 1986 Silver American Eagle on the scale. It's documented to have a weight of 31.101g. My scale measured it at 31.16g (a difference of about +0.19%). I tried weighing it with a flip and without the flip...same exact weight.
Here's my question, is it about as accurate as I will get from most scales of 0.01g accuracy or do I need to return it?
I placed a 1986 Silver American Eagle on the scale. It's documented to have a weight of 31.101g. My scale measured it at 31.16g (a difference of about +0.19%). I tried weighing it with a flip and without the flip...same exact weight.
Here's my question, is it about as accurate as I will get from most scales of 0.01g accuracy or do I need to return it?
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If you find a particular year weighs more I would sure like to know.
ZeroHedge makes debut at White House press corps briefing
1987 (2 - diff coin)=31.44g
1987 (3 - diff coin)=31.25g
1991=31.19g
Unusual? Or, simply wrong?
<< <i>I tried weighing it with a flip and without the flip...same exact weight.
Here's my question, is it about as accurate as I will get from most scales of 0.01g accuracy or do I need to return it? >>
I would think a scale accurate to 1/100th of a gram should be able to discern the presence of a flip vs a coin weighed without a flip. I'd return it.
<< <i>
<< <i>I tried weighing it with a flip and without the flip...same exact weight.
Here's my question, is it about as accurate as I will get from most scales of 0.01g accuracy or do I need to return it? >>
I would think a scale accurate to 1/100th of a gram should be able to discern the presence of a flip vs a coin weighed without a flip. I'd return it. >>
I noted that with and without the flip the weight was the same for the coin (after subtracting the weight of the flip).
Oh, I see. Never mind.
<< <i>1987 (1)=31.40g
1987 (2 - diff coin)=31.44g
1987 (3 - diff coin)=31.25g
1991=31.19g
Unusual? Or, simply wrong? >>
Weigh these coins several times. If you get the same exact weights each time, your scale is probably quite accurate.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
It's amazing how much a coin wears away. Maybe weigh them when they're less than AU.
Then instead of "Guess The Grade" with photos, we can do it in grams.
As to the accuracy of the scale, Perry hit it on the head.
I'm gonna have to start asking my bank teller if she has any in the drawer!
ZeroHedge makes debut at White House press corps briefing
I suspect your scale has higher resolution than it has accuracy. Lots of scales will post numbers down to 0.01g, but their accuracy is more like 0.05g, 0.1g, or is expressed as a +/-%.
Mine is only one digit right of the decimal point. But, I now carry that ASE whenever
I need my scale, as a check. Mine is made in China. Had it about 5 years and no
problems whatsoever.
When I weigh the same coin on my Ohaus Beam Scales it's exactly 31.1. I suspect
that your new scale is dead on.
Trick is finding a check weight or coin that you know the exact weigh on.
bob
<< <i>Weigh these coins several times. If you get the same exact weights each time, your scale is probably quite accurate. >>
What you define is precision, not accuracy.
<< <i>AU American Silver Eagles?
I'm gonna have to start asking my bank teller if she has any in the drawer! >>
I know a lot of fellows who keep one in their drawers..
2 newer BU Lincoln cents - 2.47g and 2.48g (documented weight=2.5g)
3 BU state quarters - 5.69g, 5.71g, and 5.76g (documented weight=5.67g)
I weighed each one at least 2-3 times and the weight came up the same each time for each.
This was brought to the manufacturer's attention and the Americans were told that it was necessary to create the failures in their manufacturing environment, in order to meet the American standard.
Go figure. That's "accuracy" and precision.
<< <i>
<< <i>Weigh these coins several times. If you get the same exact weights each time, your scale is probably quite accurate. >>
What you define is precision, not accuracy.
I understand and agree with what you are saying. My point was that if the scale was precise, that would be a good indication that it's a quality piece of equipment and would indicate that it's also probably accurate. It doesn't surprise me that the ASE's are slightly heavy. These coins have manufacturing tolerances and the mint purposely makes them slightly heavy so those ASE's that are on the light side of the tolerances still contain at least one full ounce of silver.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
Kove and Au and AG are correct.
To check the calibration of your scale Find a piece or two that are close to full scale values on the ranges of your scale.
see if you can get them weighed by a lab or college student in a chemistry class
with their very accurate scales (hopefully a good more accurate than 0.01 gm). Use these pieces with these measured values as your transfer check standards to see how much off your scales calibration is. You can if desired note the difference and apply it plus or minus as necessary to all your readings as a correction factor. These cheap scales may not be linearly accurate down scale so ideally a check standard at full scale and half scale would be better. Measurements at or near full scale are the most accurate. This should give you more confidence in your scales measurements.
Buying calibration weights 4 to 10 times more accurate then your scale is way too expensive for what you are doing with it.
Krueger
I also have a coin scale that is suppose to be accurate to 0.01g. It comes with a calibration weight and I
have found it to be accurate.
If you want to compare notes, give me a call.
Mark
Life member of ANA
<< <i>Early on when the Chinese were first being used in manufacture for an American company, the requirement was no more than 15 parts per million could be defective. It was determined later that there were 15 parts per million failing.
This was brought to the manufacturer's attention and the Americans were told that it was necessary to create the failures in their manufacturing environment, in order to meet the American standard.
Go figure. That's "accuracy" and precision. >>
Sounds like a failure to communicate. 15 ppm max should be a limit and not a standard. It makes little economic sense to make out of spec product on purpose just to achieve/approach an acceptable defect level. If they had a bunch of off spec stuff laying around I suppose they could blend it off rather than scrapping it.
I paid $5.22 delivered and it weighs to .01 gram. I grabbed some pennies from my pocket and threw them on one at time, all around 2.5 gm untill one was 3.11 gram. Copper.
So in response to this thread I weighted an ASE. 2011-W. 31.17 gm. I weighed several 100 grain Sierra Hollow point boat tail copper jacketed 6mm bullets and they all weighed 1.53 gm which would be .01 gm light but maybe accurate.
I'm happy for $5.22. If you paid a lot more, maybe you should consider returning it and buying the one I bought.
--Jerry
<< <i>Bah Humbug and a Pox on your newfangled toys. I've got a century old balance scale with weights and aluminum discs down to 1/2 grain. It is always correct and though slower to use its astoundingly accurate. >>
Sounds like the powder scale that I use.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
<< <i>How much did you pay for this high precision scale? Coincidentally I received in the mail today this little jewel.
I paid $5.22 delivered and it weighs to .01 gram. I grabbed some pennies from my pocket and threw them on one at time, all around 2.5 gm untill one was 3.11 gram. Copper.
So in response to this thread I weighted an ASE. 2011-W. 31.17 gm. I weighed several 100 grain Sierra Hollow point boat tail copper jacketed 6mm bullets and they all weighed 1.53 gm which would be .01 gm light but maybe accurate.
I'm happy for $5.22. If you paid a lot more, maybe you should consider returning it and buying the one I bought.
--Jerry >>
Jerry, thanks for the info. I put that scale on my watch list. I'm still considering keeping my scale. But I must admit that your scale does seem very accurate.
Oh, how do you guys carry that balance beam to in home appointments???
lol
bob
I couldn't agree more. Strongly stated, but the only way to go when seeking to accurately determine the mass of coins.
it's accurate per my beam scale and cheap, too!
bob
edited to add pic: