Digital Scale Problem

[Gary L. Griffiths]

Is it just me, or do y'all sometimes have trouble getting an exact weight on your digital powder scale? I have a relatively new Frankford Arsenal digital powder scale that I've begun using to replace my ancient Herters beam scale. This evening, while trying to throw 23.0 gr. AR-Comp, I simply could not get the scale to read 23 gr. even. I set my powder measure to throw 22.6 gr., then trickled it to 23.0 gr. Or tried to. No matter how carefully I trickled the powder, the digital scale would go from 22.8 or 22.9 to 23.1 gr. I must have tried for 10 minutes to get it to weigh an even 23 gr., then finally hauled out my old Herter's scale and followed the same procedure, trickling powder until I had the balance set to "0" on 23.0 gr. I checked each weight on the digital scale, and sure enough, I would get either 22.9 or 23.1 gr.

Is it just me, or does my digital scale just boycott 23.0 gr. for some reason?

[skizzums]

every time I have discrepancies, it is always linked to a draft ir a breeze or some kind of wobble. I have to turn off all fans and a/c, what a few minutes and then get a consistent read. you have probably tried all this already, just thought I would add in ase your new to sensitive scales

[pathdoc]

Mine does it too. I concluded it's simply not accurate to 0.1 grains and use it solely as a reality check if I'm bulk loading at least a grain off max. I use an RCBS 502 beam balance for load work up and near max.

[LE-28]

I've noticed sometimes when I'm dribbling powder to my Hornady bench scale it will hesitate when I know it should hicked over, I touch the top of my scale and it usually does.

Once I got used to running mine it doesn't present much of a problem anymore. I don't stand there and wait on it. It's still much faster than waiting on a beam scale to settle in.

[cryogenic419]

Is the surface level?? Try to get that surface as level as possible.

The fans, ac, breeze could be causing a problem but seems odd that it won't cause a problem until you hit a certain weight.

Is the scale near anything that may be putting off a magnetic/EMI fields, radio waves, fluorescent lighting, etc. Its a longshot but maybe try moving the scale to a different area to see if the problem resolves itself.

[wogpotter]

Got fluorescent lighting anywhere close?

[Brutus]

I've never trusted electronic scales. I use one just to verify I have my good old balance beam set correctly.

[Unclenick]

Many of the inexpensive digital scales are actually gram scales with 0.01 gram resolution that convert their gram output to grains. This means the resolution is actually about 0.154 grains instead of 0.1 grains, so they tend to skip or be "allergic" to producing some digits. In this instance, though, 23.0 grains is a more even conversion from grams than either 22.9 gr or 23.1 gr, so I would expect it to skip those numbers and not 23.0, unless it has an offset or doesn't round or convert correctly.

In this instance, I would be looking instead for some of the usual villains:

• No fluorescent lights, brush motors, or computer or computer monitor power supply on any circuit whose wires run near your loading bench. Nor do you want any of those kinds of devices physically near the scale. These days we commonly keep load records on a laptop or tablet or other device that shares the loading bench. If you do, try moving it away or putting a tin foil hat over it while you weigh.
  
  
• If you are running the scale off a wall wart instead of a battery, be sure the wall wart is plugged into a EMI filtered outlet, and not just a surge protected one. An old computer UPS is good for this.
  
  
• Use only a transformer type wall wart with a filtered output.
  
  
• Particularly when humidity is low, wear a computer repairman's grounded static discharge wrist band. A static charge on you can actually deflect the light weight weighing pan. Amazon has some, and the cheapest will do. Only a couple or three bucks.
  
  
• Set the scale into a cardboard box lying on its side and tape a plastic drop cloth curtain over the opening and read some weights in there to test whether or not a draft, like exhaling toward the scale, is causing the issue, these pans have a lot less mass than the beam on your scale, so they move more easily.
  
  
• Keep the scale sitting on a brick or a concrete patio walk block or some other mass that can't change temperature quickly. Set the brick or block on a couple of layers of medium pile carpet scrap to damp vibration.

Last, inexpensive scales have been getting better and better in performance terms, but they still aren't as stable as expensive ones. I've noticed that a number of the inexpensive scales get glowing reports from some users and terrible reports from others. This suggests you can get a "good" one or a "bad" one. If you can't get stable successful readings from this scale, consider returning it for a different copy and see if the next copy does any better.

[willr]

I agee with PATHDOC I use the digital scale only as a check. I have found my digital is not consistent even over its measuring platform.

willr

[higgite]

I've seen what you have described occasionally with one of my digital scales when I've used it for trickling. It isn't sensitive enough to always respond to a "mini" trickle. It may take multiple mini trickles to get it to finally respond and it will jump .2 grains. What I have learned is that when it gets to, say 22.9 gr for this example, and doesn't respond to the next trickle, pick the pan up and set it back down on the scale. That takes the "stiction" out of the measurement and more often than not it will readout 23.0 gr. You didn't say if you had tried that already, so I thought I would mention it.

[Nick_C_S]

Wow, awesome insight Unclenick. You always seem to amaze. Makes perfect sense though.

Along the same lines, but off any TFL subjects for just a sec: I have noticed for some time now that my car's outside air temperature gauge seems to be "allergic" to certain temperatures. Now that you've pointed this out, I bet it's because it's actually calibrated in Celsius in the background - so to speak - and then converts to Fahrenheit for the display. (Japanese made vehicle.)

[Jim243]

The obvious question is does one gradual or flake of AR-Comp weigh more than 0.1 grain?? Highly unlikely but who knows.

The only way to check a scale (digital or balance beam) is with a set of certified weights. Have you done this to insure your scale is accurate to start with??

But it really doesn't matter, no scale unless you spend over $600 to $5,000 will be as accurate as a lab scale anyways. And that doesn't matter either since you are loading for consistency and volume and not weight. Will 1 tenth of a grain of AR-Comp make a difference in your accuracy, I think not. But as long as all your loads are consistent say at 23.9 grains the bullet in theory should go in the same hole. Will powder on one day with 23% humidity weight the same as powder measured on day 2 at 45% humidity. No you will get two different weights for the same volume of powder. Will that make a difference in how your rifle shoots? Most likely not.

I have been loading for years with a $300.00 digital scale and I do NOT expect it to be down to 0.001 grains accurate, my meter on the scale only goes to 0.1 grain accuracy, so a measure of 23.5 grains could actually be 23.597 grains or 23.510 grains, does it make a difference, no, just as long as it is the same for each and every load for that batch of reloads.

Jim

[RC20]

Mine does the same thing, not any lately so I don't have a number.

If I remember I will try to hit your 23 with it next time I have it out.

Also keep in mind, you do have a cross check, your pan.

I have weight mine, I have the number written on it in case I forget.

A bad scale would not repeat the scale weight if no spot on.

What I do is keep a close eye on the "drift". I.e. as time goes by mine drifts off (always low). It scales at 144.6, 144.5 ok, 144.4 I re-tare it (zero it out) and back to 145.5 or .6.

Cross checks with the 502, but its always been spot on as long as I watch the drift an re-zero (tare it) and I don't worry about those missed digits.

If it won't do 51.5 (common measurement for me) then I go with 55.4 or 55.6.

No load is going to be that picky on a tenth one way or the other.

Its not a gold standard scale but if you work it right it’s a good one at a great price (assuming its consistent and mine ahs been)

I do the true re-zero from time to time, always spot on.

[Marco Califo]

Might be funny, but not intended as a joke:

Q: How do you make an electronic scale more accurate and reliable?

A: Replace, or augment, it with a balance beam mechanical scale.

They work the same, every time.

http://www.midwayusa.com/find?sortby...ensionid=15180

[Gary L. Griffiths]

Tried setting scales on a styrofoam bullet tray, and didn't run into any issues tonight with 23.8, 23.9, and 24.1 grain loads. Seems to run better on the bullet tray, plus it puts it closer to the trickler, so less powder jumps out of the pan when trickled. Haven't had time to try to duplicate the 23.0 gr problem, but it weighs the powder pan consistently as 110.0 gr, and 10 Sierra 65-gr game king bullets weighed 65.0 gr (6), 65.1 gr (1) and 65.2 gr (3).

[Sport45]

What's the scale resolution supposed to be?

My guess is the scale's native measurement unit is grams and it is converting internally to readout in grains. You say it skips 23.0 grains. Since 1.50 grams is 23.1 grains and 1.48 grams is 22.9 grains it sounds like your resolution is 0.02 grams (0.3 grains).

[Nick_C_S]

A lot of people use digital scales, and that's all well n good. But for me, I only trust gravity. (For some background: I have used many types of balance scales in a number of occupations and in personal endeavors over the years. My experience with balance scales is extensive.) I suspect I'll never part from using gravity/balance beam scales. They can't be beat for consistency and accuracy - two critical attributes for handloading.

Balance scales are less convenient, but I don't strive for convenience when I'm loading. In fact, I rather like the ritual of setting up the scale, balancing, calibrating (with check weights - but I don't always do this step), checking, rechecking. And finally, when all the rigmarole is done, I am absolutely confident that my powder throws are right on the money. I like "absolutely confident."

Okay, I'm done with the obligatory balance beam chime-in on a digital scale problem post. You're welcome.

[cptjack]

i now use a 505 scale more accurate in my opinion………….when you measure the same charge twice in a digital and have differences not for me ,

[Unclenick]

Balances have the plus factor that gravity doesn't go out of calibration. They have the minus factors of slowness and sensitivity to airborne dirt and cooking oil and whatnot. I've had one get dirty enough to settle off about a tenth of a grain high or low, depending whether the pan was above or below zero when I let go of it. So check weights are a good idea with any scale. Get a bread or cake cover for your balance beam to keep the airborne dirt and oil gremlins out.

[Jim243]

But for me, I only trust gravity

Ha, Ha that is funny. For a balance beam scale that might be OK but gravity can not be trusted. There are many reasons why, all having to do with the density and mass beneath your feet. An object weighed where I live 612 feet above sea level will not weigh exactly the same say in Denver at over 6,000 feet above sea level, and you will not weigh the same at the north pole as you would at the equator.

A 33 grain weight weighed at Lake Michigan will only be 5.48 grains at the Sea of Tranquility and 12.54 grains on Mars. But 10 cubic centimeters of powder here will still be 10 cc of powder everywhere else (except in a black hole where gravity really goes wild).

You can blame this whole thing on Albert Einstein, he said it was all Relativity. So your weights are relative to your location only as is gravity.

Jim

[pathdoc]

A beam balance is a MASS balance, if I recall correctly. This makes it independent of local values of g. Balances using springs and other stretch or compression-actuated sensors or devices are weight balances, and are at the mercy of variations in local gravitational force.

[Jim243]

^^^^^ That is correct.

[Marco Califo]

where I live 612 feet above sea level will not weigh exactly the same say in Denver at over 6,000 feet above sea level, and you will not weigh the same at the north pole as you would at the equator.

A 33 grain weight weighed at Lake Michigan will only be 5.48 grains at the Sea of Tranquility and 12.54 grains on Mars. But 10 cubic centimeters of powder here will still be 10 cc of powder everywhere else (except in a black hole where gravity really goes wild).

1. We do not reload on the Moon, or Mars, nor Uranus.

2. A balance beam scale in Denver today, will give the same result in Denver tomorrow. So local gravitational deviations are irrelevant.

The balance beam scales, while inconvenient and slow, are very practical and accurate in the application for which they are intended. More so than digital scales. Digital scales ARE more convenient, and I recently bought on for that reason. But I would not trade my beam scale for a digital one.

[Nick_C_S]

See, ^^ this ^^ is why I like TFL so much. Sure beats anything on television.

[Snyper]

If my scale would only read a tenth higher or lower, I'd just go with that load instead of worrying about making the scale conform

It's really not enough to matter