How reliable are electronic scales?

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Balrog

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I have been using an RCBS electronic scale. Using a Dillon powder measure and Winchester 748, I am getting a spread of about 0.5g (I am loading with 26.5g, and am getting anywhere from 26.2 to 26.7g).

Is this more likely to be the electronic scale causing variation or the Dillon powder measure?
 
Probably some of both.

• Not all powders work well in all measures. Someone with 748 experience will check in and tell us about that particular combo.

• Electronic scales can be more sensitive to outside influences such as voltage, air conditioning drafts, even florescent lamps I understand. The only way to be sure is to buy some check weights.
 
That's a pretty large variation for either of those instruments, but I would blame the powder measure before the scale. Do you have a beam scale to check them both? (If not, I would get one, not only for this, but for any future questions about scale accuracy.)
 
Winchester 748 is one of the best metering powders on the market. It's my "go to" powder for loading .223 Remington.

If you don't have a set of check weights to check your scale, I'd suggest buying a set. They don't cost much and they're worth every penny. Also, have you calibrated your scale recently? It should be done periodically, especially after a change in temperature.

Another thing to check is to make sure the slide on your powder measure is travelling the full distance in each direction.

Hope this helps.

Fred
 
I believe I have the powder measure set correctly. I calibrate the scale each time I use it. I just don't see why I am getting so much variation.

I don't have a beam scale, but am thinking about getting one to be able to compare. Who makes the best? Which model should I get?
 
If the powder measure meters by volume and not weight then you're going to see some variance. The finer type powders like 748 will show a larger variance than a larger extruded powder like Varget. Volume is not accurate.
 
I wouldn't trust any electronic scale without a beam to compare it to or check weights to use prior to and after a session. I'd probably only ever get one if it was combined with an electronic powder dispenser, and even then I'd have to be running out of other reloading junk to buy.

I'm spoiled and come from a laboratory background where an "inexpensive" reagent scale for measuring chemicals costs $2,000 and was rated to an accuracy of around 1/6th of a grain (10mg). If a $2,000 scale can't be relied upon to consistently measure down to 1/10th of a grain, then I have trouble trusting a $100 or even a $200 scale to do it.

I have a 40+ year old Redding oil-dampened beam balance that has never been recalibrated and it measures 175 grain MatchKings at 175.05 grains. It runs off basic laws of physics, and there isn't much there to screw up. It doesn't even use that new-fangled magnetism to dampen the beam. I can't imagine my dad paid more than ten bucks for it when he got it.

You kids don't know how good you have it. ;)

The finer type powders like 748 will show a larger variance than a larger extruded powder like Varget.
Click to expand...

I get the opposite. Imagine a bucket full of sand versus a bucket full of rocks.

748 meters to +/- 0.05 grains out of my Uniflow, I haven't used a Dillon measure. The only thing that meters better is Bullseye or Power Pistol. For comparison VV-N150 is +/- 0.2, IMR 4064 is +/- 0.3. The bigger the grain, the more variability in my hands.

-J.
 
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I have a Dillon D'Terminator. Also a set of check weights. That scale is dead on.

When I load 748 (it's my go-to powder for .223), I tap the powder measure with a large allen wrench to settle the powder. Until I do that, it doesn't throw very well.

People usually say it takes 15 or so throws for a measure to settle down, but in my case I determined it was just powder settling. So I accelerate that w/ the tapping.

+1 on the check weights. I don't know how anyone can use a scale unless they have something to validate it against, whether it's electronic or a beam.
 
Get the check weights. Having 2 scales is like having 2 watches. You never really know what the right time is. Myself, I prefer the balance beam. But even for that I want check weights.
 
Once again - someone has to explain to me how using check weights is going to solve the problem Balrog is having with a wide swing in weight readings of his powder. Check weights are an excellent accessory to have, but they don't solve this particular problem.

me said:
If a scale is out of calibration, it will be consistently incorrect.
Click to expand...
His measurements aren't consistent.
 
I saved the "check weights" that came with an electronic scale (that were used for calibration) to use with a beam scale.

After using them a couple of times, I realized I was calibrating the scale every time I set it up (with the zero knob) and that it was unlikely to lose "span" accuracy as long as I kept it clean and didn't damage the knife edges or agate blocks.

So, I am also puzzled about beam scale check weight use. Nice to know Ohaus knows how to make a scale, I suppose, but the mechanical scales generally don't suffer from the equivalent of transducer drift... :)
 
Once again - someone has to explain to me how using check weights is going to solve the problem Balrog is having with a wide swing in weight readings of his powder. Check weights are an excellent accessory to have, but they don't solve this particular problem.
Click to expand...

OK, the check weights will determine if your scale is accurate. Or needs calibration. Then you know when dumping powder on the scale pan that it's measuring the weight of the powder correctly.

I have been using a RCBS powder pro for 14 years,(made for them by pact). It has only failed me once, it needed to be re-booted. A call to pact gave me instructions on how to do that, I was calling for shipping instructions.

It is paired with the pact dispenser. But mostly I use it for weighing bullets, and setting measures.

I have the smaller set of check weights from Lyman;

http://www.midwayusa.com/viewProduct/?productNumber=212586

212586.jpg


They come in the following increments;
Check weight set includes:
# Two 20 grain
# One 10 grain
# One 5 grain
# Two 2 grain
# One 1 grain
# One 1/2 grain
For a total of 60-½ grains. That pretty well covers all non-magnum powder charges.

Another thread recently, one person who was a lab tech. said these weren't all that precise. But on my pact/RCBS scale they always weigh what they're supposed to. If they don't, then it's time to calibrate.

Another thing that most don't bother with, or just plain don't know. The surface your scale sits on must be LEVEL. No bones about it! Level in one direction, then at 90 degrees, not just level one way.

Take a carpenters level to see if your bench is level. If it is not, then you will have to either level the whole table, or provide a stiff level surface for the scale to sit on. Unless you have some weird iron rock formations underground, gravity runs at exactly 90 degrees straight up. If the scale is tilted off center, you've induced an angle into the equation.
 
I got a set of the above check weights about 6 weeks ago. That luxury was after four years of using the best reloading investment I've made in the last 20 years -- an RCBS Chargemaster/Dispenser combo.

Prior to this I've just kept a 50gr, a 69gr, and a 77gr .223 bullet to weigh at the beginnning of each reloading session. Even when I started from scratch and hadn't pre-Cal'd with the two big calibration weights RCBS supplies, that scale has always been dead on. Dead on.... (My hat's also off to Sierra & Hornady for such precise bullet making as well.)




All of which is not to say that I don't still have my 40-year old Texan beam scale on the other table when I feel paranoid. :neener:
 
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snuffy said:
OK, the check weights will determine if your scale is accurate.
Click to expand...
I seriously hope you don't think I don't know what check weights are used for! ;)

The info in your post in no way explains how there can be a variation of 1/2 grain from one weighing to the next one.

It's the variations in the weights that is puzzling both Balrog and me. All the check weight advice, while normally good advice, doesn't help at all in this case. Why is this so hard to get across?

I still say it's the powder measuring - the measure itself or the technique used.
 
I still say it's the powder measuring - the measure itself or the technique used.
Click to expand...

Agreed.... although an honest-to-golly half grain is a bit much. (Maybe +/- 2 tenths I could see were it stick powder and inconsistent powder pack-down in the column.)
 
There are two common ways to weigh powder with confidence. The old way was to have a beam scale and know it would read correctly. Today, some still work the old way while others get an expensive digital scale AND a beam scale to keep the digital honest. (This is modern "progress"?)
 
Well, one way the check weights could be used to help isolate the problem would be to bracket the powder readings with check weight readings:

weigh check weight -- get correct value
weigh powder -- get some value, maybe the same as previous one, maybe not
weigh check weight -- get correct value again

I agree that this method is not conclusive, but if the above scene actually gets played out, it suggests that the powder measure, and not the scale, is the culprit.

Tim
 
Another thread recently, one person who was a lab tech. said these weren't all that precise. But on my pact/RCBS scale they always weigh what they're supposed to. If they don't, then it's time to calibrate.
Click to expand...

That was probably me. Don't get me wrong, I believe that reloading grade electronic scales can be accurate and precise, but I'm not surprised that they might have short service lives or start doing weird things like having inconsistent measurements described above. They just don't have the over-engineering that a professional balance would have. Also, every time you move the darned thing you risk damaging the strain guages that do the measuring.

I think you just have to treat them as fickle and prone to failure and check them at the beginning and end of each session to make sure that this session isn't the one where it decides to crap out.

If you weigh every charge, bullet, or case, then you are pretty much dedicated to needing an electronic scale because beam balances are incredibly frustrating for that task by being so slow to settle down.

-J.
 
I don't think repetitively weighing the same charge will help my problem. I think my problem is that I had the scale close to the press, and manipulating the press was causing enough vibration and movement in the bench that it was affecting the scale, effectively knocking it out of calibration a little. At least that is the theory I am working with now. I have moved my scale to another table not attached to the press and am about to go throw 10 consecutive charges and see what I get. I will report back.
 
Ok with the scale moved to a table not attached to the press, here is what I got:

Winchester 748:

26.2g
26.2g
26.1g
26.3g
26.1g
26.1g
26.2g
26.1g
26.1g
26.2g

My goal was 26.2g, so I would say that I am +/- 0.1g. That is acceptable to me for my purposes. I think my problem was that slight movements in my bench as I operated the press were causing the zero of my scale to fluctuate and give me funky numbers.

One thing I have noticed with my Dillon Powder measure though is that if the press sits for a while, the first charge I throw is always high. Have other people experienced that?
 
Well, sounds like you've solved the variable weighing problem. I'm not sure how though. You weren't operating the press at the same time you were weighing a load, were you? If the zero of the scale goes off, it won't display 0.0, it will display something else, and that should be noticed when you dump the powder on the scale. If the small vibrations of the press throw the scale off zero and it stays off, then it's not a very sturdy scale.

... the first charge I throw is always high. Have other people experienced that?
Click to expand...
Yep. I automatically dump the first two throws of a session back in the hopper without even weighing them.
 
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