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Old 10-08-2012, 21:31   #41
dkf
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Quote:
Originally Posted by tkglazie View Post
yes, it has a mode button and toggles between several measurements.

for calibration, it uses the 2-weight method using the 2 provided 10gram weights.
I may try one to try since they are inexpensive. I already have a good Dillon Eliminator to test it against.

I do understand what some are saying. Just because the display reads down to .02 grain does not mean it is accurate to .02 grain. Kind of like an electronic caliper that displays down to .0005". It may have .0005" increments but nobody but a fool will depend on it below +-.002".

Last edited by dkf; 10-08-2012 at 21:34..
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Old 10-08-2012, 21:35   #42
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Why do you get so wound up about it? You reported about what the docs say exactly right. No one is doubting you. I've been using analog and digital scales for a long time and I simply don't buy their printed information as correct.

Flash
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Old 10-08-2012, 21:36   #43
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Originally Posted by dkf View Post
I may try one to try since they are inexpensive. I already have a good Dillon Eliminator so I have a very good scale already to test it with.
if nothing else its a handy backup or double/trlple check scale to have on hand. if you have any problems with yours please do share, I would be as interested as anyone since I do use mine quite regularly.
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Old 10-08-2012, 21:40   #44
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Originally Posted by ROGER4314 View Post
Why do you get so wound up about it? You reported about what the docs say exactly right. No one is doubting you. I've been using analog and digital scales for a long time and I simply don't buy their printed information as correct.

Flash
Sorry, I am just pretty offended by SARDG's post and the way some have just assumed I have no idea what I am talking about. I try hard to be a positive, helpful presence on these boards. Reloading forums got me off to a good start in my reloading life and I am grateful for that and would like to return the favor.

For the record, I have a BS in Mech Engineering and worked on some of the cooler toys in our national arsenal for one of the big defense contractors back in the day, I think I can run a little old scale
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Old 10-08-2012, 21:56   #45
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SO you are trying to tell me it measures 2/100 of a grain?
From the manual, yes it does. Since it reads to 0.001 GRAM, reading to 0.02 GRAINS is not a problem. These are not typos, the numbers are straight out of the user manual.

It would be interesting to see how it works against check weights.

Richard
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Old 10-08-2012, 22:00   #46
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They claim +- .02 grain accuracy and the norm is +- .1 grain (good) or +- .2 (fair). It could be a coincidence but it seems likely that there was an error.

If I get a chance, I'll order the Gemini and try it. For the tiny cost, it would be worth buying if it's a reliable unit. I have several digital scales that didn't work well for powder charges but they still work great for weighing bullets or other components.

For the record, I have a Masters in technology but once you get old and retire, folks think a lifetime of training and experience simply evaporates. I don't care if folks believe me or not.

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Old 10-08-2012, 23:15   #47
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Wow, I went away for a couple of hours and 25+ posts showed up before me.

I am generally a fact-checker from way back, but it is so grossly uncommon for anything costing $22 to have an actual accuracy of .02gr that no checking was deemed necessary.

However, the specs don't claim an accuracy of .02gr, they claim a resolution of .02gr. tkglazie, your original post claimed that the scale "measures to .02grains". Measures to (?), accuracy, resolution, and precision are all different animals. Take a look at this article, especially the Real-world Example at the bottom of the page that cuts to the chase:
http://www.tutelman.com/golf/measure/precision.php

The other parts of this page demonstrate how manufacturers hedge on precision and accuracy, by claiming good scores for resolution. Built in weighing algorithms may help perpetuate the illusion to the scale's end user. Repeatability and reliability are also mentioned regarding actual precision.

I too would like to prove-up actual accuracy and real precision, and therefore repeatability and reliability in such an economical package - but fear it won't measure up (no actual pun intended).

Of course, normal reloader's check-weights don't go down to .02gr, mine starting at .5gr.; so how we check the Gemini is unknown. There is another related page "Testing a Digital Scale" which seems to give correct procedures for accurate testing if you have the time and patience:
http://www.tutelman.com/golf/measure...lScaleTest.php

If I am found to be wrong, I most definitely would owe you an apology, but I am not yet convinced. My statement was actually made to convince ADK to choose wisely regarding which random posters to believe and I fear I was somewhat insensitive in the way I did that and apologize now for the insensitivity of my 'sell'.

Kitty N.
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Old 10-09-2012, 01:44   #48
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Well, for $25, I'll buy one & use it in my reloading class, the ammo is never shot, so I won't care. It certainly can't be worse than the $25 Hornady that never stays zeroed. I would expect a guy w/ a BS in engineering would know better. but hey, college isn't what it used to be. Check wts BTW, start @ 10grain & go down, not up. Check w/ certified check wts & get back to me. Weigh the same 10gr wt 10 x, it should never vary.
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Last edited by fredj338; 10-09-2012 at 01:47..
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Old 10-09-2012, 02:21   #49
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...Check w/ certified check wts & get back to me. Weigh the same 10gr wt 10 x, it should never vary.
It may NOT vary during that test. The website article I referenced above claims that circuits built into cheaper scales can mask inconsistent measurements. If a 10gr weight is placed on the scale and actually measures 10gr, the circuits will take subsequent readings within a 'range' (as an example, 9.8-10.2gr) and display them as 10gr. The author suggests "cleansing the palette" of the scale between test weights by weighing a much heavier or lighter weight in between test weights.

These algorithms are allegedly how low-cost scales can use resolution to mask inaccuracy and imprecision.
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Old 10-09-2012, 06:14   #50
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Gemini 20.

I copied this from a conversion site:
0.001g = 0.0154323580gr

I copied this description of the Gemini 20 from an on line store:

"Get quality and accuracy with the Gemini-20 digital gram scale. The Gemini-20 is accurate to 0.001 grams.

So the scale is accurate to (rounding off) 0.02 grains
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Old 10-09-2012, 06:40   #51
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I came across this some time ago and found it informative on digital scales.
http://www.mnguntalk.com/viewtopic.php?f=12&t=34414
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Old 10-09-2012, 07:04   #52
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Originally Posted by ADK_40GLKr View Post
I copied this from a conversion site:
0.001g = 0.0154323580gr

I copied this description of the Gemini 20 from an on line store:

"Get quality and accuracy with the Gemini-20 digital gram scale. The Gemini-20 is accurate to 0.001 grams.

So the scale is accurate to (rounding off) 0.02 grains
What that specific online store has done is taken Gemini's "resolution" claim from the Gemini manual, and directly equated that to "accuracy", which we've determined are not the same.

Manual (from Richard's link (Page 5):
http://www.americanweigh.com/pdf/man...-20_manual.pdf
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Old 10-09-2012, 07:51   #53
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Originally Posted by SJ 40 View Post
I came across this some time ago and found it informative on digital scales.
http://www.mnguntalk.com/viewtopic.php?f=12&t=34414
SJ 40
Well, that guy sure paints a grim picture. I'm certain that there is some correlation between this and the link(s) I posted - just not sure I'm smart enough to figure out what it is.

The scale addressed in this post is the Dillon and this same kind of conversion error isn't mentioned in the [my] former articles.
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Old 10-09-2012, 08:52   #54
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Originally Posted by SJ 40 View Post
I came across this some time ago and found it informative on digital scales.
http://www.mnguntalk.com/viewtopic.php?f=12&t=34414
SJ 40

He made a very basic mistake in that post. The D-Terminator is measuring to .003 gram NOT .01 grams as he seems to think. Look at the response from CED below.

Quote:
“The current D-Terminator electronic scale is measuring in gram and then convert the reading to grain. The error due to unit conversation will be within +-0.05 grain (equal to 0.003 gram)

No matter how, the error due to unit conversion will always be there. It is just a matter of which unit measure is more important for the application. “

Respectfully, Charles Hardy - CED
You need to be real careful reading this internet crap.
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Last edited by Colorado4Wheel; 10-09-2012 at 08:59..
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Old 10-09-2012, 08:57   #55
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Originally Posted by SARDG View Post
Well, that guy sure paints a grim picture. I'm certain that there is some correlation between this and the link(s) I posted - just not sure I'm smart enough to figure out what it is.

The scale addressed in this post is the Dillon and this same kind of conversion error isn't mentioned in the [my] former articles.

That is a very interesting article! It is WRONG, but it is interesting.

In the section "First response from me on Oct. 2, 2010:", there is a table that indicates that certain readings, in grains, aren't possible due to mathematical oddities related to rounding. For example, 4.7 grains should never show up on the scale. If the table is correct...

So, how is it that I can walk out to the garage, load up a trickler and dispense a 4.7 gr charge? In fact, I watched for missing increments on the way up to 4.7 and, except for the occasions where I was overexuberant in twisting the knob, every single reading appears.

There is certainly some technical basis for some of the author's ideas but the problem with 'facts' is that, sometimes, 'experiments' disprove them.

I think that when a reloader moves from a quality beam scale to a digital scale, they have accepted the 0.05 gr error. I know that my Chargemaster and my D'Terminator don't agree to 0.1 gr. If I set the Chargemaster to dispense 42.2 gr, I will, more often than not, get 42.1 gr on the D'Terminator. I figure there are two round off errors going on and I'm willing to accept the variance.

I use check weights in the range of interest. For a 42.2 gr charge, I use a 50.0 gr check weight. Both scales read EXACTLY 50.0 gr. That's great! But the engineer inside me also knows that I have no idea whether or not the check weight is anywhere near 50.0 gr. All I know is that three things tend to agree. They could all be wrong. But they would be wrong together!

Another thing I learned: Your measuring device needs to resolve 10 times better than the thing you want to measure. If you want to measure 0.1 gr, you need to be able to resolve 0.01 gr, accurately. Which means that none of our common reloading measurements are worth a darn - engineering wise.

But, darn, they seem to work anyway... Experiments...

Richard
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Last edited by F106 Fan; 10-09-2012 at 09:03..
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Old 10-09-2012, 09:00   #56
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I think if I was CED I I would sue him and make him get rid of that slander.
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Old 10-09-2012, 09:03   #57
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Originally Posted by F106 Fan View Post
In the section "First response from me on Oct. 2, 2010:", there is a table that indicates that certain readings, in grains, aren't possible due to mathematical oddities related to rounding. For example, 4.7 grains should never show up on the scale. If the table is correct...

So, how is it that I can walk out to the garage, load up a trickler and dispense a 4.7 gr charge? In fact, I watched for missing increments on the way up to 4.7 and, except for the occasions where I was overexuberant in twisting the knob, every single reading appears.

Richard
Because the article is wrong. The Scale measure to .003 grams which means it's accurate to .05 Grains (actually a little better) and then the scale rounds to .1 grains. So it has more resolution then it needs for it's given task. Not less as he falsely is asserting.
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Old 10-09-2012, 09:07   #58
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Don't be surprised if you see a correction in that website in the near future.
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Old 10-09-2012, 09:09   #59
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Because the article is wrong. The Scale measure to .003 grams which means it's accurate to .05 Grains (actually a little better) and then the scale rounds to .1 grains. So it has more resolution then it needs for it's given task. Not less as he falsely is asserting.
Exactly! As you pointed out, Internet stuff isn't always correct.

Richard
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Old 10-09-2012, 09:18   #60
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Originally Posted by ADK_40GLKr View Post
I copied this from a conversion site:
0.001g = 0.0154323580gr

I copied this description of the Gemini 20 from an on line store:

"Get quality and accuracy with the Gemini-20 digital gram scale. The Gemini-20 is accurate to 0.001 grams.

So the scale is accurate to (rounding off) 0.02 grains
Yeah, so it says. Let's see, they are trying to sell you something and?????????
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