Ever Checked Your Electronic Scale?

[ROGER4314]

I've studied up on digital scales and found that a scale weighs using a specific standard. If you press the button to convert the scale reading from (for example), grains to grams, it still reads on the design standard but the microcomputer converts the reading to the one that you choose. In conversion, changes occur due to rounding of decimals.

I use a desk lamp on my reloading bench and it uses the new fluorescent type of bulb. One night, I was loading 44 magnums and the scale began to vary a lot. It turned out to be the desk light and I suspect it was either the very small amount of heat produced by the light or interaction with the transformer built into the bulb.

Let's be honest about these scales. There are 7000 grains to the pound and we expect +- 1/10 of a grain accuracy. Most instrument accuracy is expressed in % of full scale. A 1000 psi gauge of 1% accuracy can vary +10 psi to -10psi and still be in tolerance.

By expressing accuracy of a flat +- 1/10 grain, that is an extremely accurate instrument! These little digital scale have fantastic accuracy and are very sensitive to outside variables like heat, wind or vibration.

Think about that. If a scale is a 1500 grain full scale unit with +- 1/10 grain accuracy (2/10 grain total allowable error). The percent accuracy of that scale is .00013333%! Accuracy like that was only available in laboratories 50 years ago!

Help me out here, I'm trying to understand the problem if my scale is incorrect. I guess what I'm trying to say is, if the end result is always the same, why should I be concerned about a problem that doesn't seem to exist?

If you want to measure 10 grains of powder with an accuracy of +- 1/10 grain, the scale can read 9.9 to 10.1 grains and still be in tolerance.

I was a fanatic about accuracy long ago but found that minor variance in powder charges had very little influence on accuracy. My .308 reloads were chronographed at 15 feet per second extreme spread for a string of rounds. That's way beyond good! Don't sweat the powder charges. They just don't cause large variance in accuracy. Work on your marksmanship skills. That is a HUGE variable!

Flash

[tbird1960]

Whether the scale is exact or not is immaterial. They are mechanical devices and are subject to being wrong. If you reduce your loads 10% and go from there you will be safe. If you load the cartridge and it flattens or blows the primer it is too hot. Unless you want to spend a couple of thousand dollars for a scale that is laboratory grade you are beating dead horse. Use the same measuring device every time and you will have no problem. Better yet quit loading maximum loads. The deer will not know if it is shot with a bullet that is a little slower.

[darkroommike]

[QUOTE=tbird1960;1957205]Whether the scale is exact or not is immaterial. They are mechanical devices and are subject to being wrong. If you reduce your loads 10% and go from there you will be safe. If you load the cartridge and it flattens or blows the primer it is too hot. Unless you want to spend a couple of thousand dollars for a scale that is laboratory grade you are beating dead horse. Use the same measuring device every time and you will have no problem. Better yet quit loading maximum loads. The deer will not know if it is shot with a bullet that is a little slower.[/QUOTE

I see a lot of confusion here between the terms: exact, accurate, and consistent

For reloaders the most important of these concepts is consistent. Forget exact, exact can only be achieved by something like the National Bureau of Standards.

Accurate is good but it's not important. On reloads the difference between 34.5 and 34.6 grains of powder while working up a load is insignificant, your powder meter will vary that much. To get good reloads neck tension and case volume are much more important (and if you're using a progressive press with range brass your manufacturing process is much more loose than your scale).

Consistent is what we are shooting (groan) for. We want a powder measure that throws the same load every time (within practical limits). We want YOUR scale to measures YOUR loads consistently after you use YOUR check weight to ensure that nothing on the scale has gone out of whack.

It's a check weight NOT a Bureau of Standards "gold plated calibration weight".

If you have five scales, that's four too many to use.

[HATCH]

I bought a electronic scale from Brian enos
I calibrated it using the weight and instructions.
It read 100.00 at that time.
It reads 99.99 right now.
I can live with the 1% shy reading.

We aren't doing brain surgery here so being off a tenth of a grain isn't a big deal.
In fact if it is repeatable every time then there isnt a problem for you.


sent from my mobile.

[dragon813gt]

Help me understand. I've been through all the posts and I think I'm missing something.

I didn't to quote the entire post so I cut it off. Let's say the scale is off .3 grains. Do you know if it's off high or low? With cartridges with small charges this can be a big issue. With rifle it won't really matter. But you can easily exceed max charge in a small charge cartridge if the scale is off. Some cartridges only have .5 grain difference between min/max.

Yes you want the scale to weigh the charge correctly. But you also want repeatability. This is why I have major problems with the battery powered scales. The weight can vary drastically depending on where you place the item on the scale. This is what's unacceptable to me. I need the scale to give the same reading irregardless of where the item is placed on the scale.

Unless you are working with small charges the scale being off a few tenths of a grain isn't going to matter much. But if you have a scale that will vary a grain or so, depending on where the item is placed, I wouldn't use it. You have no way of knowing what the curve looks like in regards to how much it's off as the weight goes up/down.




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[ReloaderFred]

I calibrate my PACT Professional Scale on a regular basis with the supplied check weights. I also occasionally check it with the Lyman Check Weight set that I purchased many years ago. I very seldom find that the scale has changed, but if the ambient temperature changes quite a bit in my shop, it will affect the results.


One thing I do to check the tolerance stack in the accuracy of a charge is to make whatever adjustments I need to with my powder measure to get to the desired weight for the given powder. Then I'll throw 10 charges of that powder and see if the powder measure is throwing a consistant charge, but it also checks the accuracy of the scale at the same time. Say I'm looking for a charge of 3.4 grains of Bullseye. I'll adjust the powder measure to throw that charge, then by extrapulation 10 charges should weigh "exactly" 34 grains. Most times it will be a couple of tenths of a grain plus or minus, which simply means the scale "may" be reading at the upper, or lower, end of 3.4 grains, which is a very small measurement. Then I adjust accordingly, if at all.

Hope this helps.

Fred

[sgabel1]

Guess what? You get what you pay for. I have a used Mettler PE balance accurate to +/- 1 mg
or 0.001 gms. I got a good deal on Ebay for $135 they retail new for around $1600. If you know statistics there are two measures. Accuracy which measure a values closeness to a known and precision that is a measure of repeatability. Generally the cheap balances do a poor job at both. .1 gr = 6.4 mg so the cheap scales can read +/- this value so you could expect a scale capable of .1 gr allowance of 19.9-20.1grs if your target weight was 20.0 grs.

Now look at the Mettler above if you do the math this scale is capable of +/- 0.016 grs.

The only drawback I found with my Mettler balance if that i need to create a chart in Excel that converts grains to grams as it does not have the capability of reading in grains!

Another note is your calibration weight should be close to the powder weight you are going to dispense if you want to check accuracy.

I think darkroommike has a good suggestion that if you stay 10% below max you should be safe.

[winelover]

I started reloading before electronic scales were the norm. As a result, I have a RCBS and Lyman beam. Bought a RCBS Chargemaster when they came out and I use it exclusively. However I always calibrate it first and secondly, I compare it's dispensed charge against one of the beams. They always match!!!!!!!!!!!

Winelover

[Kevin Rohrer]

I checked my 10-10 using the 2-weights provided with the 750. Before doing so, I leveled the 10-10 as best I could. According to it, the 20-gram weight that should weigh 308.65gr weighs 308.3gr, and the 30-gram weight that should be 463gr. weighed 463gr. Does that mean that the 20-gram weight is actually .35gr light, and does it matter? I also checked the weights on the 750, and they weighed 308.7gr and 463gr respectively.

My concern was for accurately weighing small charges like 2.8gr of Bullseye, but a check of the load range for the 38Spl shows 2.5-3.1gr in the acceptable range.

But what does it say about the calibration of the 750 if the smaller weight is actually .3gr less that it should be? Perhaps it is Parallax error on my part as Roger4314 suggests; I don't know.

I don't experiment with maximum charges, except with the .221FB. But as I have just purchased Quickload, will make sure I don't go overboard. But it would be nice knowing if I want to throw a charge of 17gr of L'ilGun for the cartridge, that I am not actually throwing 17.3gr, which might be a problem.

I am currently loading for my M1A using BLC-2. I threw 10-charges on my Quick-Measure and weighed them on both scales. Here is what I saw:


750 10-10
46.4 46.1
46.4 46.1
46.4 46.1
46.5 46.2
46.3 46.0
46.4 46.05
46.4 46.05
46.1 45.85
46.4 46.1
46.4 46.1


Which one should I trust, and does it matter?

[Sonnypie]

Those are nominal weights. What tolerance does the mint specify?

Ima,
That was from a web search. http://wiki.answers.com/Q/How_much_does_a_dime_weigh
Got there from here: https://www.google.com/search?q=How+...a&channel=fflb

Facts is, money gets dirty from handling, finger oils, boogery fingers, and such.
Then there is wear from pockets and other change.

Makes me think of the Machinist lament...
10 machinists could read something, and all 10 readings could be infinitesimally to grossly different.

I can put something (bullet) on my cheap-O digital and get a slightly different read each time I take it off and let it 0, then set it back in the pan.
Oddly enough, my Lyman 505 balances the same each time with the same bullet. So I rely on it for my needs. Which is to check random powder throws.
And the trigger goes plink, and the hammer goes clunk, and the firing pin goes whack, and the primer goes pop, and the gun goes BOOM!
Humm, missed that bulls eye again. Must be that darn scale.

[imashooter2]

Ima,
That was from a web search. http://wiki.answers.com/Q/How_much_does_a_dime_weigh
Got there from here: https://www.google.com/search?q=How+...a&channel=fflb

All the observed weights were under 2% variance from nominal. So we're right back where we started. We don't know which, if any, of the scales were correct weighing that particular dime.

[Moonman]

I use a Brian Enos Electronic, I check it with RCBS Check Weights and against

another electronic scale, I have several.

I only load handguns also.

[ROGER4314]

I'll repeat something that I posted earlier. As a former accuracy obsessive person, I proved to myself that powder charges can vary a bit between rounds without a measurable change in consistency. I check my charges, reload ammo and pause to recheck the charges every so often. Beyond that, I'm just not going to worry about it.

The biggest factor in dropping consistent charges is banging around on the bench where the powder measure is mounted. That will pack the powder in the reservoir as you work and vary the charge drop weight. If you DO bump the bench, do it the same way for every charge. The measures convert powder volume to weight in grains. If you supply a denser powder supply to the volume chamber of the measure, the weight of the charge must increase.

As a former instrument tech, I enjoy fiddling and experimenting with the scales but that has NO bearing on my reloading procedures. I have two sets of calibration weights and I actually handle the weights with tweezers but that's because I know how to calibrate and maintain my equipment properly. I turn the fans off when weighing my test charge and keep heat sources away from the scale. That's all.

Don't sweat the small stuff, work on your marksmanship and have fun! Your marksmanship techniques are the biggest variable in shooting accurately.

Flash

[Mike Kerr]

I have found that the scales generally available to us as reloaders are not perfect when compared to "more scientific " models, but they are still ahead of us "as shooters".
However, I guess we all need something to blame, and a scale can be a good scapegoat in a pinch.

regards,

[LUBEDUDE]

Roger/Flash has excellant points. Afterall, take a good look at your bench, or even pics posted here. Most, mine included, are not exactly laboratory spec. Or in a sterile environment for that matter. Just taking that into consideration, an awful lot of guys manufacture some pretty awesome accurate ammo here. Many put factory ammo to shame.

For garage/basement operations, we ask and expect a heck of a lot of performance.

[Awsar]

i check mine before every load session its a dillon had it close to 20 yrs now still working good.has a built in calibration feature.

[Kevin Rohrer]

i check mine before every load session its a dillon had it close to 20 yrs now still working good.has a built in calibration feature.

That's my point. It appears that one of my calibration weights is .3gr short, which means it calibrates that much over. Or does it?

My next step is to get a set of check weights. I am off to Midway.

[Kevin Rohrer]

This is a followup.

I got a set of RCBS check weight scales and tested them on both scales. On the 750, the weights were spot-on; on the 10-10, they showed to be a bit light (am guessing .4gr; I will check it later today).

Soooo, from now on, whenever I use the 10-10, I will first use the check weights to 'zero' the scale. And I will trust the 750 when it has been calibrated.

[jrkoop]

I just got a Horizon Pro-50A electronic scale on Amazon for $45.99 shipped. It's accurate down to .02 grains and I'm actually quite impressed with how good it works. Of course, always back up everything you do with a good beam scale, but for convenience and good accuracy this scale is hard to beat. I'm actually surprised not more folks in the reloading community know about this little scale. For the money I've not found any other digital scale that comes even close; and I've scoured many reloading forums and read hundreds of posts and articles to research which scale to get. As far as I'm concerned this is a supreme deal for the money. Got it today, calibrated it, tared it. Everything appears to work flawlessly.

[Lloyd Smale]

I agree. .1 of a grain means about nothing. Ive got a pact dispensor a lyman dispensor and a rcbs beam scale and they all weight the same charge within a .1 of a grain. Even if all of the are showing heavy it doesnt matter much to me as long as next time i use them they do the same so i get the same load.

I have both the RCBS Chargemaster and the Dillon scale. When using the Chargemaster and the scale says it dispensed 18.0 gr & instead of pouring the powder into a case I pour it into the Dillon pan, Dillon says 18.0 gr. On a rare occasion there will be a 0.1 gr difference. When I weigh a boolit on the Dillon and it says 188.2 gr & then weigh the same boolit on the RCBS it also says 188.2 gr. On a rare occasion there will be a 0.1 gr difference.

The Chargemaster per instructions is calibrated before each use with the supplied weights. The Dillon is not but I check it on occasion with the weights.

I figure the scales are plenty close for me, if they are off, inaccurate or faulty they are both off, inaccurate or faulty pretty much the same.

Rick