alright, i put new batteries in the digital scale, and calibrated it. the beam scale is zeroed perfect. I charged 74.5 grains on the beam scale, then weighed it on my digital scale and it is .3 grains difference. I'm not sure if .3 grains is something to be concerned with on a charge this large as long as it's consistent. However, i still can't figure out why the digital scale reads light after calibrating it to the check weights. I still feel like it should be more consistent between the two than .3 grains. still scratching my head......
lee scale issues
- Thread starter hvychev77
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jfh
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You don't say which digital scale you have--but keep in mind that, unless it is a very high-test expensive one, running on a wall voltage supply, its accuracy is most likely expressed as plus or minus one tenth grain, at best, on the digital scale. Combine these tolerances on both scales, and the ES will be 0.4 gr.. That's above your current variation.
That's one factor, then. Then, even if the checkweights--what, 20 gr? 50 gr. are precise (and I believe they probably are), there can be variations due to dust and fingerprints on them. Finally, the only way you will get any sense of significant inaccuracy here is to measure ten or 20 loads at a time and then calculate the standard deviation at the 95% level, for both scales.
I suspect you may have forgotten about digital scales having a tolerance factor, too. Unless one heads over into precision lab equipment that costs much, much more than we spend for our reloading gear, I don't think you will get more accurate reading.
As for whether that perhaps 0.5-gr. 'actual' variation--at this level, it represents about 1 /1500th variation in charge weight--and, more appropriately, about 1 / 225 variation (0.3 gr.)--is an issue for your firearm, I can't tell you that. But, IMO, I'd trust the balance beam.
Run 10 charges out on the Lee, and see what the aggregate weight of all ten is. Do no excess powder handling--i.e., dumping from one tray to the next, etc. Weigh it on the digital scale. Repeat 10 times, and do the SD, etc.
Jim H.
That's one factor, then. Then, even if the checkweights--what, 20 gr? 50 gr. are precise (and I believe they probably are), there can be variations due to dust and fingerprints on them. Finally, the only way you will get any sense of significant inaccuracy here is to measure ten or 20 loads at a time and then calculate the standard deviation at the 95% level, for both scales.
I suspect you may have forgotten about digital scales having a tolerance factor, too. Unless one heads over into precision lab equipment that costs much, much more than we spend for our reloading gear, I don't think you will get more accurate reading.
As for whether that perhaps 0.5-gr. 'actual' variation--at this level, it represents about 1 /1500th variation in charge weight--and, more appropriately, about 1 / 225 variation (0.3 gr.)--is an issue for your firearm, I can't tell you that. But, IMO, I'd trust the balance beam.
Run 10 charges out on the Lee, and see what the aggregate weight of all ten is. Do no excess powder handling--i.e., dumping from one tray to the next, etc. Weigh it on the digital scale. Repeat 10 times, and do the SD, etc.
Jim H.
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Sport45
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That's because the digital is calibrated to that check weight.
How much does the check weight weigh on the Lee scale? Take it to the pharmacy and ask them to weigh it on their balance.
I wouldn't be surprised if your calibration weight is off a tenth or so. I'm guessing it's not a calibrated weight, but rather the check weight that came with your digital scale?
Balances are typically more accurate than digital scales. Since they aren't measuring anything (just balancing loads on either side of a pivot point) they aren't even affected by small differences in gravity.
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