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Old September 16, 2011, 03:50 PM   #26
FlyFish
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"The digital comes with 2 check weights, one 20grams and another 30grams."

I hope you mean 20 and 30 grains.
No, I'm pretty sure he means grams - my PACT digital came with 20 gram and 30 gram weights. I wouldn't really call them check weights; they're intended for use in calibrating the scale, and at one point you actually put both weights on together to give you 50 grams. I'd hesitate to "check" the accuracy of a scale with a 20 gram (= 308.6 grains) weight and then proceed to use the scale to adjust my powder measure to throw, for example, a 10 grain powder charge. Much better to check the scale with a weight close to the charge you want to throw.
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Old September 17, 2011, 08:29 AM   #27
Mike Irwin
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I'm actually surprised that you found that much variation. Coins are supposed to be held to pretty exact tolerances.

What may be the case, though, is that given that coin compositions have changed over time, you might very well have gotten some older coins with different cladding or blank standards.

I think it would be more indicative if you were to weigh coins from the same time frame.

That said, just about anything can become a check weight, including a coin, a metal nut, etc., as long as you weigh it carefully to establish its weight and hang on to it.
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Old September 17, 2011, 01:03 PM   #28
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you can order individual check weights from the Ohaus website. I ordered a 20g one fro $10. I didn't want to order a whole set and end up spending as much on weights as the scale costs
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Old September 17, 2011, 01:11 PM   #29
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I have a dime that I wrote "35" on with a Sharpie that I use for a check weight. The key is that i use the same dime every time. It doesn't matter what its weight really is; it is close to 35 grains and I decree it to be exact

For the kitchen scale, I use whatever few nickels I have handy. They weigh 5 grams each, the composition doesn't change as much year-to-year as pennies and once-silver coins, and they are plenty close enough for a kitchen scale.
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Old September 17, 2011, 03:38 PM   #30
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Yeah, sure. It weighed 35 grains before you wrote on it, but what it is now?

The father of a friend of mine used to say there was no point in arguing about a fact. It was either so or it wasn't. Just look it up or measure it.

For nickels, I didn't find a single pair in the house from the same year. But here's what I got. The year is noted. There was no obviously severe wear on any of them, but the wear would be different, off course. The newest one looked sharpest and had the highest weight. I ordered them from lowest to highest weight and you can see the years jumping around some. Interestingly, the second oldest (1981) had the second highest weight.

Code:
   Weight	        Year
74.59 grains	1980
75.50 grains	1997
75.68 grains	1995
76.27 grains	1994
76.31 grains	1998
76.80 grains	2002
76.88 grains	1977
77.02 grains	1999
77.06 grains	2001
77.20 grains	1974
77.22 grains	1981
77.76 grains	2007

76.52 grains	Mean
 3.17 grains	Extreme Spread
 0.90 grains	Std. Dev. (estimated for total population (all nickels in existence) by n-1 denominator method; 0.86 for this actual 12 coin population.)
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Last edited by Unclenick; September 17, 2011 at 03:44 PM.
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Old September 21, 2011, 10:01 AM   #31
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This should work for you:

http://www.scalesgalore.com/product/?product_id=12314

Just a little over your budget, but DEFINITELY worth it.
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Old September 21, 2011, 10:18 AM   #32
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Glad they have free shipping.
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Old September 21, 2011, 10:32 AM   #33
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Yep, US coins are more than exact enough to be used as check weights.
Only if they are brand new.
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Old September 21, 2011, 10:54 AM   #34
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Wouldn't you just pick one, weigh it, verify it on another scale, write down what it weighs, then use it over and over. If you are careful with it, it is probably not going to change weight.
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Old September 21, 2011, 11:03 AM   #35
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wow,this thread seem to make the process difficult, i have a Lyman balance beam and an RCB 750, when I start a new batch I calibrate the 750 compare it to the Lyman if the match up good to go after 2 years only found small variance if the Lyman was moved from it's position. I do like having both as an extra safety measure,
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Old September 21, 2011, 11:45 AM   #36
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I use the check weights that came with my BBK scale, or for a quick check I use a .308" 168gr SMK that I've verified to weigh 168grs on the nose.
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Old September 21, 2011, 03:31 PM   #37
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gram weights are a mass produced item, and have been used to calibrate digital powder scales for a while.

My older pact uses a 20 gram and a 50 gram, and points of zero, 20 grams, 50 grams, and 70 grams to calibrate and align.

This gives it a 4 point fit.
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Old September 24, 2011, 06:21 AM   #38
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cheap vs smart-n-safe

Really?
A Lyman or RCBS scale weight check set costs too much?
Please......

I consider a check set MANDATORY, like eye protection.
I use my set to confirm a charge weight on my scale each and every time I set up; without exception.
Always.
Every single time.
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Old September 24, 2011, 09:35 PM   #39
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I'm not disagreeing that a standard check weight is worth the cost, as I don't want to feel foolish about the 20-odd ones that I own. But I will point out that if you cut a length of stainless wire to match a load at the time you weighed the charges for the load development work, and it suddenly doesn't read the same as it did before, you know something happened to the scale, and know that something affects the scale at the exact weight you are trying to measure. That gets you around any kind of linearity error a particular design might have.
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Old October 8, 2011, 02:12 PM   #40
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Just one last one on coin precision. I finally got someone who's been collecting state quarters to lend me 35 Utah quarters. These all have the Philadelphia mint P symbol (there were some D's, but not enough for a significant sample size so I excluded them) and all are 2007. None appears worn significantly. The results were:

Mean Weight: 87.68 grains
Standard Deviation: 0.45 grains
Extreme Spread: 1.96 grains (Highest: 88.70 grains: Lowest: 86.74 grains)
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Old October 8, 2011, 02:26 PM   #41
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Mean Weight: 87.68 grains
Standard Deviation: 0.45 grains
Extreme Spread: 1.96 grains (Highest: 88.70 grains: Lowest: 86.74 grains)
Prety bad when we are trying for 0.1 grain accuracy and repeatability.
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Old October 8, 2011, 03:33 PM   #42
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Again, you are not weighing coins. Pick one, verify the weight and keep it.
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Old October 9, 2011, 03:27 PM   #43
brickeyee
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Again, you are not weighing coins. Pick one, verify the weight and keep it.
All that tells you is if something changed.

For that matter you could use a bullet, or any other object.

It does nothing for actually meeting a standard.
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Old October 9, 2011, 05:06 PM   #44
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All that tells you is if something changed.
Isn't that enough? Why not?
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Old October 10, 2011, 10:12 AM   #45
brickeyee
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Isn't that enough? Why not?
Not if you are trying to use loading data developed by someone else.

Now you need to be certain that their scale and your scale are at least reading reasonably close to each other.
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Old October 12, 2011, 10:53 AM   #46
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Yep. A grain of error can take you well over the top with some loads, especially in small capacity pistol cartridges. And that's just for those UTAH 2007 coins from the Philadelphia mint. As soon as you mix the coins, be it quarters or nickels (I still don't have a large enough sample of dimes to see if they're any different, but I don't see why they would be) it looks like about 4% spread is what you have to accept. If you can keep them all the same year and mint, you might cut that in half, but only if the year isn't so long ago that some have a lot of wear.
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Last edited by Unclenick; October 12, 2011 at 11:02 AM.
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