Got my new coin scale yesterday

Hi all,

I bought a DigiWeigh DW-100AX scale for weighing my coins, and it arrived yesterday. Before I purchased it, I made sure that it weighs down to .01 grams. That was a great suggestion that I picked up from this forum. The scale only cost me $25. The seller paid for shipping.

It does seem to be a rather delicate piece of hardware, but I think that's to be expected for something purchased for $25. It's something that I'll have to keep out of the reach of my 21 month old son

I haven't started checking the weight of the coins in my collection as they're at the bank. However, I did practice by weighing some nickels, dimes, and quarters from regular change.

Something that I noticed while weighing the regular change is that what my scale was showing as the weight of the coins was just slightly different than what my Redbook shows as the official weight. For example, I weighed several Roosevelt dimes, which Redbook shows as 2.27 grams, but my scale showed them as 2.25, 2.24, and 2.28 grams. I gather that there's probably some standard deviation in weight that acceptable. Is this correct?

When I bring my collection home and start checking the weight of the more valuable coins, at what point should I get worried? If one of my half eagles shows .05 grams difference than Redbook, does that mean that it's likely to be counterfeit?

What are the standards that you all use to test the weight of your coins?

-StephenS

 

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I prefer Tanita take it back or have it re-scaled at the shop.

 

I bought one of these as well. Minor fluctuations in weight are to be expected. Some here told me that tolerances were actually tighter back in the 1400s than they are today. Today, as in the 20th, 21st century, tolerances became much looser.

I don't know at which point you should start to worry but I think it would be pretty obvious. I've noticed well worn coins to be sometims 0.15 grams under weight. While some good condition coins are slightly higher than book weight.

I calibrate it every time I start it up, with the weights that came with it. I've noticed it's sensitive enough to where you can't even breathe near it or the weight fluctuates. I like mine so far.

Edit: BTW, 0.15 grams sounds like a lot but this is 0.0048 of a troy oz. So before you would get too concerned, realize this is a very minor amount of material. This should put the 0.05 grams in perspective.

 

Would normal wear on old silver coins account for the .02 gram difference?

 

Yes, and then some, would be my guess. They may have been made 0.1 grams under tolerance to begin with and then had 0.02 or more worn off of them in circulation. This is a very small amount. Look at an old worn quarter. A lot of the design can be totally gone around the outside.

 

I noticed that it registers a weight when you breathe on it.

So, assuming the fact that there may be a small difference in weight in legitimate coins, would counterfeit coins be significantly different? If so, by how much? I guess that's a hard question to answer because there isn't a 'standard' counterfeit coin to compare weight to.

I guess what I've been looking for is a clear number variance to look for when weighing to determine if a coin is genuine or not. Perhaps there isn't one, and what I should do is look at the readout of what my scale says and use my better judgement.

 

I used to scales where you can watch water evaporate.....

Oh well, not for the house

Ruben

 

I've wondered the same thing myself. I imagine good counterfeits would match the weight close enough to where you couldn't tell.

I know there have been people who purchased common St. Gauden's $20 coins, melted them down and produced counterfeit gold coins worth much more out of them. So the metal composition would be correct. If they got the size right, the weight's going to match. Probably hard to pin point some counterfeits by weight alone, if they're good.

 

FWIW, if anyone runs across this thread down the road.....

The book "United States Gold Counterfeit Detection Guide" by Bill Fivaz, lists the mint's weight tolerances and proper diameters of all U.S. gold coins, in the back of the book. Just remember circulation wear can have a 'minor' effect as well.

 

I have noticed that there will be varience (sp?) due to the scale changing temperature as well.

 

I've got the same scale and I see similar variances as you're finding. I don't intend to weigh all my coins but whenever I have any doubt, I use the scale.

Bruce

 

As a rule of thumb on all measurement devices, especially low cost ones. A 1% overall accuracy of full scale is considered very very good. Thus %1 of 100 grams = 1 Gram. The number indicated for this device is only in reference to it's RESOLUTION an extremely deceptive number if not fully understood. If your meter has .01 resolution it will display but the accuracy is still +-1 gram if it is %1 percent accurate. Considering this meter is such a low cost device and the manufacture has not speced this accuracy % it may very well be higher and 5% number would not be out of line.

Not sure how this meter will effect the true weight of your coin(s) under test. One way to better the odds would be to find a true standard and use this to measure the meter's accuracy (not the one sent with the meter ) before basing any expensive purchasing decisions on this or any meter's readings.

 

No way these are off by 1 gram. As I said, I calibrate with the two 50 gram bars every time. I also happen to have some test weights for calibrating a scale for gun powder. Only these are in grains, which are much, much smaller. The 1 grain weight is a tiny, straight piece of metal about 1/4" long that is so light, you cannot feel it in your hand.

I set the scale to 'grains', set it on there and sure enough, it registered 1.0 grains exactly. One grain is 0.0648 grams. The other calibration weights were dead on every time as well. Never off by even 0.1 of a grain.

I do have one smaller though at half a grain. The 0.5 grain weight was too light and didn't register on the scale. FWIW.

As far as the low cost, from what I've seen, it has more to do with the limits of the upper end of the scale. These only weigh up to 100 grams or roughly 3.5 troy ounces which isn't much. Low end accuracy isn't sacrificed. Surprisingly. You start paying much more when they can be this accurate but can still weigh heavier objects.

 

That model has a readability of .01gram as stated by the manufacturer. The algorithm for rounding .00x will determine the centigram reading. If x =0-4, then the 2nd digit will round to the lower number ( i.e. .074 = .07 , if .076 = .08g ) unless the platform is covered, air flow can cause a flicker between 2 numbers on the last digit. Because a carat is only .20g and a .98 carat diamond sells for much less than a 1.01ct diamond ( over 1 carat don't you know ~advertising) most jewelers have a scale that is .001g or .0001g readability.

By the way, be careful with the pan of the scale. lifting it instead of the scale can really mess up the strain gauge sensor which does the measuring, as can putting much heavier weights than the maximum.

Jim

 

There are two aspects to a scale which need to be considered. One is the minimum weight that it can accurately weigh according to some standard, and the second is the precision.

For example, a scale might need a minimum weight of 0.5 grams. Anything less it can not weigh accurately. And then it has a precision of 5 mg. So is a weight of 5mg causes a 0.5 g weight to tip, but a 1mg extra weight can not be read on the scale with a 0.5g weight.

It doesn't tip the scale accurately.

Of course there is a max weight that a balance can take as well

Ruben

 

http://balance.balances.com/scales/1293/

 

http://www.pharmacybalances.com/display/show/36
cheap and great for coins

 

http://cgi.ebay.com/Mettler-H31AR-Balance-Scale-Used-Clean-and-Works_W0QQitemZ400002682556QQcmdZViewItem?hash=item400002682556&_trkparms=39%3A1|66%3A2|65%3A1|240%3A1318&_trksid=p3286.c0.m14

This is like the one I have and use. I converted the support pivot to allow weighing a stone or coin in air and then is a basket in water to determine the specific gravity. Good way to estimate if a gold coin is close to correct % gold, as well as weighing it. It has a resolution of .0001 or .1mg. These are usually available from college labs changing over to all electronic ones as these can be tempermental to align after the UPS man "delivers" them.

Jim

 

There's no way to lift these by the pan. They're a pocket scale. I know there are more accurate scales. But I am shocked at how good these are for how cheap they are. I think there's something to be said for the technology. It's gotten better and cheaper.

I have to believe these are more than an adequate for weighing coins, for what we're trying to do, as long as you keep them calibrated.