Beam scale is off

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grubbylabs

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So I just got my beam scale back from Hornady. They were supposed to check it out and make sure it was weighing correctly. I was specious because I was getting different results between it and my RCBS Charge Master. The Charge Master seemed to be more along the lines of what I would suspect. I was weighing match grade bullets and the charge master said .1-.2 grain difference, so a 200 grain bullet would weigh 199.9 or 199.8 but my beam scale put the same exact bullets at 200.6 to 200.8.

So I called Hornady and they had me send it in. I got it back and it was still off. It zeros out just fine, but it is still off. So I had my wife take it to work and check it against the test weights they use in their lab at the Hospital.And sure enough, my scale is off from their weights. And it seems that the more weight you add the worse it gets. at 30 grams it was 1 full grain off. the bullets that I weighed on my Charge master came back the exact same weight. So I know at least the charge master is on.



So what beam scale do I try next?
 
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Bullets, even match quality bullets make a very poor standard to check the uncertainty of a scale. Typically a match bullet like a Sierra 168 grain HPBT Match King has an allowable tolerance of +/- 0.3 grain.

While I find it hard to believe Hornady would rework a scale and release it with an out of tolerance error sometimes stuff happens. Fortunately your wife can take the scale into work and have the hospital lab guys run some standard weights across it.

What I would try next? Have your kind and considerate wife take the scale back to work and ask the nice lab guys to check the scale calibration again. This time annotate the results with real numbers. Have them, if they would, run the scale checking Maximum weight and divide the scale Max weight by five and check about 5 cardinal points. That means if your scale is a Hornady LNL Beam Scale like this one the specifications should look like this:
Capacity: 500 Grains
Material: Cast Aluminum
Units: Grains
Accuracy: +/- 0.1 Grains
Features:
Hardened Pivot Pins & Bearings
Molded Pan Hanger
Made in USA
Easy-to-read laser etched bar
Magnetic Damper
Click to expand...

Set up zero and check the scale with test weights applied of 100, 200, 300, 400 and 500 grains. Note the exact weight the scale indicates for each applied weight. You want to see if the error is linear in nature. You also want to note the error. Again, bullets, even match bullets, are not test weights.

Then with the new data the scale goes back again to Hornady.

Ron
 
I know bullets are not test weights, that's why she took it to work and used the check weights she uses to calibrate her lab equipment.

But I agree, I will have her check it at different weights to see if there is a pattern.

It just baffles me that a been scale can have problems like this.

She did take some notes, but she only wrote down the information I asked her about.


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grubbylabs said:
I know bullets are not test weights, that's why she took it to work and used the check weights she uses to calibrate her lab equipment.

But I agree, I will have her check it at different weights to see if there is a pattern.

It just baffles me that a been scale can have problems like this.

She did take some notes, but she only wrote down the information I asked her about.


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Click to expand...
I agree it is unusual to return from the factory out of calibration. Possibly it took a hit somewhere along the way? There are procedures and methods to calibrate and return to tolerance beam scales like this but the procedures, while similar, vary from scale to scale. A simple Google of "balance beam scale calibration procedure" will bring up some suggested methods and videos on the subject.

Your options are pretty limited in that you can attempt to fix the unit yourself or it takes another road trip.

It just baffles me that a been scale can have problems like this.
Click to expand...

Most of the times and there were not many, problems with beam scales being out of tolerance were the result of them being hit or dropped. Bad knife edges and broken or cracked stones the knife edges resting on. Every now and then dirt but generally inaccuracy in scales of this type it was physical damage. Unusual? Absolutely it is. :)

Ron
 
I do not have a Hornady scale to look at but it should be similar to my Redding and RCBS scales . A diagram of the RCBS calls the little aluminum pan that holds the powder a scoop and the scoop sits in the pan , the pan is suspended from the beam on a support system (bent wire)
Okay...take a close look at the pan, there should be a screw that connects a small compartment filled with small weights (birdshot). I'm shaking mine and can hear them rattling. Unscrew it and either add birdshot or remove birdshot to make it weigh the correct amount. Balance beam scales are not complicated and this rather primitive method works surprisingly well. This is how the factory calibrates them and you can do it yourself. If you have a known check weight and lets say it needs additional weight , just add small shot to the pan until it weighs correctly. Then unscrew the compartment and add. Do the reverse if it needs weight removed. You can use anything for weight, shot is just handy, but anything will work. I've trimmed little bits of flat lead into the correct weights before.
Gary
 
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That scale is a 5-0-5 scale, which means at the ends of its design it is +/- 5% accuracy, and accurate at its intended zero range. (5-0-5 is also a brand name by RCBS, but this is a design description of the accuracy of gauges, scales, and the like.) Your scale is within specification for the equipment, which would be for measuring grains of powder at a far lesser charge weight. At 200 grains, it would be allowable to be off considerably more.

We would do well to remember this, as this is one reason we work up our loads for our firearms so it is safe.
 
Gary, the Hornady scale does not have any thing like that. It's just a plain aluminum pan in a wire basket.


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If I understand exactly what is going on here, your scale is reading about .8 grains more than your chargemaster. I would order another wire basket first. Get a good pair of wire cutters and snip off a small section. You could drop this section on your digital scale to judge your progress. The goal is to get it as close to the weight that the chargemaster shows for the same check weight. Be conservative and sneak up on this weight. You may get lucky and the newly purchased wire basket will be closer to the correct weight. If you go too far cutting the wire, you already will have a backup.
My Redding #2 scale was heavy as well by .2 grains. It has the small compartment with bird shot in it. Now it's .05 grains lighter than my Chargemaster.

In a former job, I was certified in Texas to repair and calibrate scales used in grocery stores and such. It's not a difficult job but always clean all the build-up off the scale first and reset zero. If this weight is not acceptable, adjustments will need to be made. Once you get close, disassemble your scale( remove the beam and pan), put it pack together and see if you get the same reading as before. Adjust again if necessary.
 
The scale zero's no problem. But it consistently weighs on the heavy side. I could calibrate it to read .8 grains under instead of zero, but that's not right either. It should just work.


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Hmmm, I took my LEE safety scales and my el-cheapo Frankford Arsenal Digital scales to work and had our calibrations lab check them, both were dead on.

I would show the results to the manufacturer and send them back again.
 
I agree that the chase of perfection in scale readings is folly. As a result of such folly, I own multiple beam scales: LEE, RCBS 502/505/510/1010 & 304, & also several digital scales.

I tested them up one side and down the other, and I still don't think I have a good understanding of scale reading fluctuations. One thing I do feel I understand is that scale readings/responses are not linear across the scale's range.
For example, this RCBS 304 is dead-nuts from zero to 45 grains, both with the scale accuracy relative to test weights and itself. 50 to 500 grains, not so much :)

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Powder scales can be very susceptible to interference by air movement from your AC or heater. This is why laboratory scales are contained within a cabinet that prevents such air movement from interfering with the scales accuracy.

When I've found discrepancies in measurements in my Ohaus 5-0-5 its often been the AC, a fan or an open window. Other times the scale was bumped and one of the the poise, usually the 0 to 1 grain 1/10 measurement was bumped off or not hanging properly or the beam was pushed a little off center.
 
I have a lyman (D7 I think) It is fine using the main 5gr increment poise. It is off using the secondary 0.1 gr poise. For example if you put a 55 gr bullet in the pan and set the main poise on 55 it balances. If you then set the main poise to 50 and the secondary poise to 5, it is no longer balanced. Its repeatable, I've done it with check weights also.
 
Scales will make you want to pull your hair out sometimes if you are OCD about things. As long as they are very close, and more importantly, consistent, there is no need to get overly concerned.

So what beam scale do I try next?
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Pick a color and go for it.

But my question would be does the scale jive in the range you will be weighing powder in?
 
Walkalong has it right repeatability is what you want. Almost all beam scales will have error somewhere along the beam. If it reads the same repeatedly then it is good. The issue is the beam itself. It varies in weight from end to end. And you place the scale weight to either side of a light or heavy spot. If you cut it up into little pieces they would vary just slightly. This is what you see with mmorris's table.
 
Well that's the problem Walkalong, it does not. I work up ladder tests for my rifles and need .4 grains to be .4 grains al along the ladder.

I usually dispense the bulk of the charge from my Charge master, then put it in my pan and trickle up to my target weight.

So my bullets I sent with my wife. I weighed those on my charge master before she took them. At her work they weighed the same as they did on my charge master.

So a Hornady 200 grain ELDX Bullet weighs 199.9-199.8 on my Charge master and my wife's scale at work. On my beam scale it weighs 200.6-200.8. So to me that's a pretty big swing.




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Make yourself a check weight that is the weight you want. Zero your scale to the check weight. I used shanks from broken drill bits to make myself a few weights that were what I wanted. I didn't have a lab scale but I had 2 good electronic scales. I'm fairly confident my weights are within .1 gr of what I wanted, I'm very confident they are the same every time I use them.
 
I think you would be better off getting your wife to weigh something much nearer your powder charge weight - if you get a 40'ish grain bullet weighed accurately then set your scale to that weight, then level it out with the adjusting foot, I don't think you will be far off. 10 grains either side of that should be within a single kernel or so, even if the scale doesn't read zero when it's empty. You could have a minute burr in the very first notch on the beam not allowing the poise weight to sit right down in the notch.

....I see John beat me to it there:)
 
And it seems that the more weight you add the worse it gets.
Click to expand...

My groups open up the farther away I move the target. Makes sense.


I think I'd be a lot more concerned about it being that far off in the 1-20gr scale than being off by .8 at 200. The higher the weight, the less significant the deviation. Whether is a bullet weighs 199gr or 200.7 grains is insignificant. as long as your scale is consistent, you can still measure uniformity.
 
I went through a half dozen of the Hornady beam scales. They either had the magnets installed backwards and the beam would not settle or they were doing exactly what yours is doing.
I really liked the scale as I thought it was going to be like the Hornady Pacific M scale. Unfortunately it wasn't to be as I really wanted it to work and tried everything that I was capable of doing.
Seth from Hornady ended up sending me a electronic bench scale which I am really happy with. I realize it only has a year warranty compared to the beam scale but am confident Hornady will treat me fair if I do have issues with it.
 
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