weighes and measures

I have an 1859o seated dollar, it has been cleaned (harshly) at some point. This was a learning experience for me. I had the coin weighed and it weighed 26.6 where specifications call for 26.73. I am aware that this is due to wear. However the diameter measured 37.850 and spec calls for 38.1, my question is will normal wear cause this much wear on the diameter.

 

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Is the reeding worn/gone? That might explain the discrepancy in the diameter as well as the weight loss.

 

It is not worn down completely. Here is a picture.

 

I think the weight is within mint tolerances.
I'm sure that someone that knows more about this coin will come along soon with more info to help you.

 

The tolerance on those is +/- .097 grams. Although most weigh quite close to the specification of 26.73 grams, a range of 26.633 to 26.827 is considered within 'specs'. That is for newly minted coins, so some would come off from wear. It would be an interesting experiment if one took a UNC. common date Morgan , weighed it carefully and then used it as a pocket piece and record the weight at AU, EF, to see how much weigh decreases with wear.

 

The funny thing is that I am doing that now. I am not using a morgan ( I could not bring myself to do it) I am using a MS Eisenhower.l have carried it to work in my pocket for the past 6 months. I am starting to see wear already.

 

Did you weigh it before you started ?

 

Yes it was 22.64g . But my experiment was more or less based on the old tootsie roll commercial about how many licks it would take to get to the center. Same concept except I wanted to see how long it would take to get to the copper center.

 

How long did it take to get that much wear?

 

No. A loss that great on the diameter would eliminate most of the reeding from the edge. With that diamet I would strongly suspect a fake.

 

I would be worried about that one.

 

I wouldn't. I never worry about the weight or diameter of coins in my black cabinet.

Seriously, bear in mind that the weight of a planchet can vary somewhat, but the diameter is a completely different matter.

The planchet is placed in a collar and squeezed under mucho, mucho pressure, which invariably causes it to spread to whatever space is within the collar. In other words, diameter isn't going to vary to any measurable amount.

 

I have a couple of morgans that are worn to about the same degree, I will measure them and compare.

 

In doing the math the diameter is only off by 0.651%. The morgan was less than spec as well but not as much (0.42).

 

How are you measuring the diameter? Getting 1% accuracy may be a bit tricky if you're using the wrong tools.

I (still) haven't done the detailed weight vs. grade study that I've been talking about for years, but weights start to decrease substantially as you get down to the AG-G range, with smaller coins showing greater percentage losses than larger coins.

 

Is the diameter determined by the dies/collar? or by measurements taken by sample afterwards. I have always assumed the former, but don't know if the end product is measured or examined. The reason I ask is that it has been widely said that the striking of a coin produces a good amount of heat, so is it possible that the planchet/coin is in a heat expanded state when it is limited by the collar device and then decreases a small %, when it is measured in a room temperature environment? Thus a slightly smaller diameter might be normal. The best I have is a digital caliper to .01 mm and on 4 Au or better Morgans within reach, the diameter was 38.14, 38.10, 38.07, and 38.09. The only calibration that I have is to set at 0.00, but I will try to find a calibration standard that is calibrate to a certain temperature, but if anyone else has a laser or lab device and standard, please measure some $, and see what you get.

Jim

 

I wasn't arguing that. I was fairly sure at what point the 38.5 is determined as the nominal diameter as I can see where the collar would be a limiting wall when struck normally, but I am wondering what the temperature is of the coin when the dies begin to pull away from the struck coin and the collar releases. I could then calculate how much negative expansion ( shrinkage) of the diameter . A quick calc based on .999 silver shows that if the coin hit 400 degree F., and then cooled to room temp., the shrinkage on a 38.5 mm coin would be about .17mm. The idea that if the collar was 38.5 mm diameter, the coin in hand show be also if uncircuated is very common, and I think may well be incorrect.

Jim