Scale questions

[bobinpa]

Hi guys. I have a couple of concerns with my scales and I would like some opinions. I have pretty much come to my own conclusion but I would like some input. I have 3 scales that give me different readings. I would like to get unbiased opinions, so I will keep the scales nameless. This is what I have.
Scale A is fairly new electronic dispenser scale.
Scale B is an older desirable model beam scale.
Scale C is also an older (even more desirable) model beam scale.

Look at these numbers and tell me what you think?
Scale A 0 250.0 207.9 51.9 85.0 66.4
Scale B 0 249.9 207.9 51.7 85.0 66.3
Scale C 0 250.1 206.9 52.0 84.3 65.5

The zero is when they were zeroed, obviously. The 250 number is a check weight and all the other numbers are bullets. I went over this a few times just to make sure I wasn't any crazier than I usually am........ I am guessing that as I move the weight along the beams to different settings that the scales just differ a little, but I didn't think they would differ a whole grain.


Is this common? I can understand +/- .1 but shouldn't all 3 scales come up with the same number on the same object? If yes, what should I do? I usually use the dispenser/scale to "throw" the charge then trickle to my final weight with one of the other 2 scales........ I really like scale C but should scale C sit in the box on a shelf or what?
Thanks in advance for your opinions.
Bob

 

[Pappy42]

Being hard headed, I would redo the test. After checking the obvious things such as leveling, lube to the bearing surfaces of the balance beam scales, air drafts and handling the clean objects to be weighed with tweezers or something other than fingers.

Good luck.

 

[jonbearman]

My guess is drafts from a leaky window or the furnace coming on and off.The first scale is either a Lyman or Hornady,2nd,10-10,and finally a 304 dial o grain .I never thought my ceiling mounted register would cause trouble but boy it sure did.I had to plug it.Fluorescent lights can and will cause havoc as well as direct sunlight on anything that is very precise.Do the test again with proper leveling and do it where there is no draft and incandescent light bulbs lighting the room.

 

[Lapua40X]

My guess is drafts ... Do the test again with proper leveling and do it where there is no draft and incandescent light bulbs lighting the room.

You may even find that your own movement in the area adjacent to the scale will affect the readings. Just moving your arm through the air around the scale (depending on how rapidly you move) can change a reading. One reason why I'd do it again is to attempt to find some linearity in the outputs. You'll note that in your data some scale readings at a given weight are comparatively higher than the one you compare it with then in the next comparison it's lower.
For example:
(Highest reading emphasized)
Scale B 0 249.9 207.9 51.7 85.0 66.3
Scale C 0 250.1 206.9 52.0 84.3 65.5

 

[bobinpa]

Thanks for your input. Seems like you guys had the same reaction as I did.... ??? When I said I went over it a few times, that was an under statement. I have been playing with this for a few days.
1. There are no heat ducts or windows in my reloading room.
2. The 3 scales are lined up on my reloading bench side by side, so they are all leveled on the same surface.
3. There is 1 flourescent light in the middle of the (9' x 9') room, but what can that cause or why? If it is the problem, why are 2 scales very close with the third one off?
4. I am weighing objects, mostly bullets to get my numbers. I place a bullet on a given scale, walk out of the room for 5 minutes or so, come back in the room, read the scale, pick up the bullet, wipe it off and place it on the next scale.....etc
5. I thought maybe I had a malfunctioning scale, and maybe I do, but both beam scales are very sensitive. They both move with 1 full kernel of H4350, so I don't think anything is binding, so to speak.....

This is driving me crazy... and it doesn't make sense. Am I missing something?

 

[bobinpa]

Lapua40X,
Thanks for your input. The numbers I posted are a small sample of what I have been going through for the last couple of days on and off......... I don't want you to think this is a non stop project. Scales A & B are usually within .1 of each other, while scale C is out in left field.....
I am at a point where I just want to leave it alone for a day and come back fresh and maybe pick something up I have overlooked.

jonbearman, 2 out of 3 isn't bad....... pretty good guessing. or searching.

 

[Lapua40X]

... They both move with 1 full kernel of H4350, so I don't think anything is binding, so to speak.....

This is driving me crazy... and it doesn't make sense. Am I missing something?

Maddening, isn't it? One long shot is that you open a door to enter the room (that moves air) and you walk across the room (that too moves air) and a scale sensitive enough to register one full kernel of H4350 could "feel" that air movement. However, truthfully, there's no telling where the devil lives in the details of your experiment. But don't let it keep you up nights.

 

[Dave T]

However, truthfully, there's no telling where the devil lives in the details of your experiment. But don't let it keep you up nights.

This is so true and scales are one topic that gets the most attention in all the shooting forums that I belong to. Lapua40X is correct, with a tuned beam scale you better not even fart. I find that even breathing will cause a problem, so I'm so anal I use a surgical mask just to contain my breathe. If I was to add anything, I would ask if maybe static electricity could be a problem if you have been doing these tests during this cold weather we are having, I see that you live close to me and static has been terrible.
Dave T

 

[bdale]

My 304 is extremely sensitive to air currents, also i would not recommend putting oil on my scales if anything i would clean knives and agate bearings with some alcohol make sure they are clean ,also dust will affect them as well

 

[bobinpa]

I never thought of static electricity........ How would that effect a scale? I have also heard that flourescent lights can as well but I never understood how that would happen either.

 

[bobinpa]

OK, Scale A is an RCBS charmaster, scale B is a 10-10 (older, made by Ohaus) and scale C is a 304.

The 304 is the most sensitive of the bunch, So as i explained, I have set a 208 gr Amax on the scale and walked out of the room. I let it "settle down" for about 5 minutes or as long as it takes to put wood in the wood burner or something. Then I come back in and sneak up on it, make sure it isn't moving and it is almost a full grain off...... in some ranges. It isn't off in all ranges though...... When I set the 250 gr check weight on the CM it settles down at 250 on the nose, the 10-10 is .1 less and the 304 is .1 more. So .2 ES between 3 scales. Pretty good IMHO.

Is it possible that each scale is sensitive and accurate on it's own, but they just don't paralell each other? I would hate to think that is the case....... Does anybody else have more than one scale to try and duplicate my findings?

Life was so much simpler when there was only one...... ;D

 

[Lapua40X]

I never thought of static electricity........ How would that effect a scale?

Static electricity can certainly affect the accuracy of an electronic scale.
It's important to keep plastic of any kind away from them and static in the surrounding environment might also contribute to reading errors. Keep all plastic stuff (funnels, ammo boxes, etc.) away from the scale and spray surrounding carpets with a laundry anti-static product.
Avoid using an electronic scale in the vicinity of any electronic device such as a radio or computer, etc. and keep in mind that flourescent lighting can generate interference for electronic scales. Turn off the flourescents and use an incandescent light if you can.

 

[Lapua40X]

Life was so much simpler when there was only one...... ;D

Kinda like life with girlfriends, kids and (if you've had the exprience - I haven't but I've heard from guys who have) wives. ;D

 

[VaniB]

What matters is which one of those 3 scales that you have will keep returning closest to the same reading the most consistantly. I got so frustrated with powder scales, that at one point I went out of my way to own 5 beam scales at the same time just to study and compare them to each other. They will not be identical, so don't drive yourself nuts. I eventually learned that it doesn't matter how they compare to each other or how the brass test weight reads. Consistant performance is what matters.

 

[bobinpa]

Life was so much simpler when there was only one...... ;D

Kinda like life with girlfriends, kids and (if you've had the exprience - I haven't but I've heard from guys who have) wives. ;D

I was married once....... it took me a while to get over it but it wasn't anything that another safe full of guns couldn't heal..... I have had friends get married since and they always complain or at least talk about how much the wedding cost....... I just smile and tell them that it costs a lot less to get into that "wonderful institution" than it does to get out of it. Then I ask them to remember me when they decide to sell the guns that they won't be using as much as they once did........ ;D

 

[jonbearman]

This is how or why I trust my electronic and have a beam scale as a backup.I start near the bottom of suggested charge weights and work up till the pressure comes on and stop and reduce slightly for safety.Then I play with seating depth.I would'nt pull your hair out on this situation.They are all similar and starting at the charge weight of lowest to highest will let your rifle decide what it like's.Comparing charge's to duplicate is a moot point because you are working up in small increments to find the node anyway's.

 

[BoydAllen]

Strain gauge scales have their limits, and unless they have been tuned, balance scales may not repeat as well as they could if they were. For me repeatability is the most important issue. If calibration is off a bit, but it is consistent with the same weight, I don't think that it matters too much (within limits, for reloading). A tuned balance can be very sensitive, and repeat well. Having done sever for myself, and seen the favorable reports on Scott Parkers work, lacking the budget for a magnetic force restoration scale. I will stick with my tuned balances. Recently, I used a webcam to put the magnified image of one of my scale's pointer and scale on my computer's monitor. With that advantage, I saw consistent increased deflection as I added individual granules of Varget. Unless I plan on cutting grains, I think that that is good enough.

 

[1066]

Strain gauge scales have their limits, and unless they have been tuned, balance scales may not repeat as well as they could if they were. For me repeatability is the most important issue. If calibration is off a bit, but it is consistent with the same weight, I don't think that it matters too much (within limits, for reloading). A tuned balance can be very sensitive, and repeat well. Having done sever for myself, and seen the favorable reports on Scott Parkers work, lacking the budget for a magnetic force restoration scale. I will stick with my tuned balances. Recently, I used a webcam to put the magnified image of one of my scale's pointer and scale on my computer's monitor. With that advantage, I saw consistent increased deflection as I added individual granules of Varget. Unless I plan on cutting grains, I think that that is good enough.

I agree with all of that Boyd. Consistency/repeatability is what you are after. Once you have settled on your load with your scale it needs to be the same every time, the fact that it's either side of the exact set weight, within reason, it's really not a problem.

The Chargemaster is always spot on? Well yes, it says it is. If the charge was three or four kernels of Varget light or heavy it would still be within +/-.1 and would still read "spot on". The same load on a good beam scale, with a spread of maybe six kernels of Varget would show a significant deflection.

Here's a simple trick that might be worth a try.

http://bulletin.accurateshooter.com/2012/07/monitor-balance-beam-with-magnified-image-on-smartphone/

 

[Area Man]

What matters is which one of those 3 scales that you have will keep returning closest to the same reading the most consistantly.

That's what I would think.

 

[CatShooter]

If scale accuracy concerns you, then a set of check weights is mandatory.

http://www.midwayusa.com/product/163721/rcbs-deluxe-scale-check-weights-5105-grains?cm_vc=ProductFinding

You know what they are, and you can mix and match them, and then graph any errors.

For powder, I use a Lyman Ohaus M-5 that I overhauled myself and I replaced the dampening magnets with stronger ones.

The beam will move on one grain of H-322 (but you need a magnifying glass )

I have owned a few digital scales, but they are not stable enough for powder. The one I have now (a Dillon) is limited to weighing cases.