Reloading Scale Accuracy

[joeb33050]

RELOADING SCALE ACCURACY
On 9/10/07 I tested my RCBS 10-10 scale, using three bullets and five other pieces of lead alloy, for a total of eight test pieces.
The procedure was to weigh each test piece once, then re-zero the scale.
I weighed the set of pieces a total of ten times.
I weighed each set five times, did some errands, weighed each set three times, more errands, finally weighed each set two times.
The scale was then re-zeroed ten times.
The test pieces weighing 183.3 grains and 39.0 grains weighed the same for each of the ten tests.
Here are the weights of the other six test pieces, all in grains:
257.5, 257.5, 257.4, 257.4, 257.4, 257.4, 257.4, 257.4, 257.4, 257.4
436.9, 436.8, 436.9, 436.9, 436.9, 437.0, 437.0, 437.0, 436.9, 436.9
154.2, 154.2, 154.2, 154.2, 154.2, 154.2, 154.2, 154.2, 154.2, 154.1
159.6, 159.6, 159.6, 159.6, 159.6, 159.6, 159.6, 159.5, 159.5, 159.6
188.2, 188.2, 188.2, 188.1, 188.1,188.2, 188.1, 188.1, 188.1, 188.1
74.0, 74.0, 74.0, 74.0, 73.9, 73.9, 73.9, 73.9, 73.9, 73.9

Here are some observations:
I pull the beam, at the pivot point, toward me as each test piece is weighed. If the beam is at some place other than toward the operator, weight variations can occur. This means that if I do not pull the beam toward me, taking up the slack fore and aft in the pivot point, sometimes a different weight for a given test piece will be seen. This has been true and my practice for many years with this scale.
The location on the pan of heavier and bigger-in-area test pieces can vary the indicated weight of the test piece by half of a tenth of a grain. A 45 caliber bullet and a long sprue showed this variation.
During any test or weighing of a series of items, the pointer should approach zero from the same direction each time. From below is the direction when I'm dribbling powder. Approaching zero from up or down, randomly, can give false readings.
Frequently the beam pointer ends up pointing almost at zero. At one weight it is high, reduce the setting by .1 grain and it is low. This because the sensitivity of the scale is greater than .1 grain. This means that sometimes, frequently, the operator must decide on the closest reading.
The scale is most accurately used when the pointer scale is at eye level; otherwise the zero depends on the relative height of the operators eye. This is an uncomfortable height for me to operate a scale at, and the error is very small, less than half a tenth of a grain; so I use the scale on a table top, well below eye level.
In all cases except one reading, (436.8), all the ten weights recorded were within a .2 grain range. Either, for example, 257.4 or 257.5. Without a lot of explanation, this is a variation of +/- .05 grain.
This test did not measure the ability of the scale to weigh a known weight and zero at that known weight. Means that no known weight of, for example, 50.0 grains was weighed and found to zero at or weigh 50.0 grains. This test did measure the ability of the scale, (and operator), to zero at the same weight repeatedly for ten tries.

joe brennan

[Bass Ackward]

Joe,

Before you started this, did you clean out the balance point? I usually use something like Gun Scrubber when I notice any variation or sticking. I keep a cover over mine to keep out the dust and minimize the need to clean it.

Job is famous for his patience. At this site we have you. :grin:

[shooting on a shoestring]

Some thoughts:

1. What you've shown is the repeatability or precision of you balance.
2. If you're looking to measure it's accuracy (to see if the weight it shows is close to actual weight), you need a couple of calibrated (and if you're really picky NIST traceable) weights. You can buy some cheapies that are good enough.
3. If you use the balance for powder, 0.1 gr repeatability is really overkill b/c in most cases, powder charge position at the time of firing induces much more variation in velocity than can be seen by 0.1 gr differences in powder charge weight.
4. I use an old Redding undampened balance and read it a the top of its swing and the bottom of its swing, take the span and divide by 2 to get the weight. Sounds complicated but its faster than a magnetically dampened balance can come to rest, and doesn't have any magnetic field errors.
5. A beam balance is simple and durable and you can easily spot a problem with the balance. Electronic ones can easily mask their errors and lead you astray at any time with no warning.
6. Air currents are the nemisis of precision weighings. They can easily be generated by temperature differences in the balance pan and what is in the pan, as well as body heat if you leave your hands near the balance, and from room air currents moving around from all sorts of sources.
7. I have my balance on a shelf that is independent ie not connected to my reloading bench to keep vibrations from my reloading press from shaking my balance.
8. Keeping the knives and anvils (pivot points) clean and sharp, and keeping body oils off of the balance pan and what you're weighing are big factors in performance.

[montana_charlie]

RELOADING SCALE ACCURACY
On 9/10/07 I tested my RCBS 10-10 scale,
My 10-10 carries the Ohaus branding, so you can have an idea of it's age.

The 10-10 is unique in that it can be kept 'disassembled' with the parts stored in a dust proof chamber. That is why I bought the scale, and is the way I keep mine when not in use.

Mine sits on an eye-level shelf that is not connected to my loading bench, so it stays free of those vibrations. I value that aspect because the vibrations would cause unnecessary wear on the knives from the agate bearings. It is for that same reason I don't keep the beam mounted in the bearings during non-use.

The base is always kept 'zeroed', and I verify that each time I assemble the scale, but I (almost) never have to adjust it. I ran a quick check in response to your thread, and was not required to adjust it this time, either.

The test I did was this...

My wife bought an electronic scale about a year ago which came with no 'test weight'. I used a small cloth bag with a drawstring to make one using birdshot.
I weighed the bag on my 10-10, then weighed out enough 'loads' of shot to make up a one-pound total. I weighed the package on the new electronic scale and it agreed that it weighed a pound. I gave the 'test weight' to my wife so she could track the accuracy of her scale as it ages.

For this 'test' I assembled my scale just as I would for a reloading session...no special postitoning of the beam, or anything else.
After verifying the 'zero', I disassembled the 'test weight' package and weighed all of the elements.
Adding up the numbers, the result was one pound plus 3 tenths of a grain.

This convinces me that a 10-10 (even a thirty-year-old one) that is properly maintained requires no special positioning of it's elements to be accurate. But proper maintenance must begin when the scale is new, and can never be allowed to lapse.

That maintenance consists of two simple chores.
- Protect the scale from vibration whenever the beam is mounted, and dismount the beam when not in use.
- Keep the knives and agates free of ALL foreign materials. This includes dust AND lubricants.
CM

[Whitespider]

I’ve had my RCBS 5-10 scale for over 25 years now. Its performance is utterly repeatable, time after time. Mine also sits at eye level and I also always remove the beam when not in use. Because the scale is magnetically dampened, it must be set up away from anything metallic (even a nail in the wall) or magnetic. I store it in a wooden box I built years ago, the beam hangs on pegs in the back of the box. The pivot bearings and knives must be kept absolutely clean and dry for top performance. Just a tiny bit of dust or residue will affect accuracy.

Here’s a hint. When I first got the scale the beam did not sit perfectly horizontal when zeroed, it was real close but not perfect. I would get variances of .01-.02 grains with it set up this way. I took the weighted pan hanger apart (there’s a screw on the bottom) and found lead shot of different sizes in there. I added and removed different size shot until the beam hung perfectly horizontal when at zero. After that the repeatability also became perfect.

[imashooter2]

Just for grins, I took a nice shiny new dime and passed it around to all my friends to be weighed on their scales:

RCBS beam = 34.7 grains
Dillon beam = 34.6 grains
RCBS beam = 34.5 grains
Redding beam = 34.5 grains
PACT electronic = 34.5 grains
Dillon electronic = 34.4 grains

What did I learn from that? A man with a watch always knows what time it is. A man with two is never sure.

[leftiye]

Yup! They're supposed to be within a tenth of a grain. As advertised. Repeatability is all that counts, as it allows us to make the same loads over and over, and you do have to work up the load anyway, etc..

One more thing you can do after you clean the stones and the knives, is to remove the magnets, makes the scale much more sensitive. Takes longer to come to rest, so learn to stop the swing (not completely) by blocking it with your finger about one tenth mark below center. While you're weighing a charge, keep the dish that the charge is in swinging moderately- keeps the scale from hanging up. Yeah, after all that, they do still hang up.

[joeb33050]

Joe,

Before you started this, did you clean out the balance point? I usually use something like Gun Scrubber when I notice any variation or sticking. I keep a cover over mine to keep out the dust and minimize the need to clean it.

Job is famous for his patience. At this site we have you. :grin:

I "clean" a lot of stuff with a 1" paintbrush, just keeping the dust off, and there isn't much of that because of the AC/filter. I've stopped a lot of the cleaning with solvents that I used to do.
(I used to wash and clean motorcycles, then watch stuff rust. For the past ~15 years I spray oil on most every metal and plastic part and wipe the dirt off. Then spray again. No rust. I don't do this very often. Oil the forks once a week or so.)

I used to take the scale apart and put the cover on. I stopped that, and now leave the scale assembled and uncovered. I figured I was doing more harm to the knife/pivot things by the frequent taking apart and putting together, so I leave it assembled. Probably assembled and covered is best.
joe brennan

[joeb33050]

Some thoughts:

1. What you've shown is the repeatability or precision of you balance.
2. If you're looking to measure it's accuracy (to see if the weight it shows is close to actual weight), you need a couple of calibrated (and if you're really picky NIST traceable) weights. You can buy some cheapies that are good enough.


As long as one starts low on the powder charge, then works up, there is no problem with a scale that repeatedly reads "off".
Accuracy is about at least three things,
"does it read WW.W when I put a known WW.W weight in the pan?"
"does it do that across the range?"
"does it repeat readings, across the range"
All I did was the third. The reason has to do with my experience that all scales I've checked against each other were very close, differences about tenths of a grain. Also, because there's nothing one can do with a beam balance if it reads "off", other than constructing an unusable correction chart or throwing the thing out.
If a scale zeros at 49.0 grains with a 50.0 grain weight traceable to NIST, all you can do is throw it out. A scale/beam balance can't be calibrated, no more than a 6" ruler or a 0-1" micrometer caliper.
And, I've never even heard of a scale out by a grain.
So, that's my thinking.
joe brennan

[joeb33050]

Here’s a hint. When I first got the scale the beam did not sit perfectly horizontal when zeroed, it was real close but not perfect. I would get variances of .01-.02 grains with it set up this way. I took the weighted pan hanger apart (there’s a screw on the bottom) and found lead shot of different sizes in there. I added and removed different size shot until the beam hung perfectly horizontal when at zero. After that the repeatability also became perfect.

I read this a lot, and thought about it, and now realize that it is a joke. Think about it.
joe brennan

[randyrat]

Yep sounds like a dang cat hair got in there somewhere. I blame my wife for getting the cat. Now whenever i'm in my gun room the cat comes in and i have to pet her and i know a single cat hair will screw up your weights/scale once in a while. You should see the cat run when i get the "can O air" out. Anytime i can't have the pussNboots in the Room all i do is set the "CAN O DEATH" in thje doorway and she stays out. Thats how you train a cats.

[montana_charlie]

Here’s a hint. When I first got the scale the beam did not sit perfectly horizontal when zeroed, it was real close but not perfect. I would get variances of .01-.02 grains with it set up this way. I took the weighted pan hanger apart (there’s a screw on the bottom) and found lead shot of different sizes in there. I added and removed different size shot until the beam hung perfectly horizontal when at zero. After that the repeatability also became perfect.I read this a lot, and thought about it, and now realize that it is a joke. Think about it.
joe brennan
I'm glad you figured it out and said somthing, Joe.
I thought he was serious.
CM

[leftiye]

Damn you're subtle.

[shotstring]

I hardly use my RCBS 5-10 or 5-5 scales anymore. Just to check the initial weight of the pour from my powder measure - from then on, all my powder sees is a good powder measure. They are just as accurate as the scales and a whole lot faster. Even the 1000 yard shooters don't weight each charge anymore. Well....1 or 2 of them might.

For bullets and such, my old scales work great because RCBS will replace the jeweled pivots for free under their lifetime guarantee, even if you are not the original owner. So I gave them a call and they sent me replacements for all the worn parts on both my scales, which I picked up used on ebay. Now all I need to do is set the level with the screw-in legs while using test weights occasionally and they are dead on.

[Woodtroll]

I read this a lot, and thought about it, and now realize that it is a joke. Think about it.
joe brennan

All right, I'll bite. The gentleman tweaked his pan weight to get the beam level when he zeroed the scale. (Zero does not mean the beam is level, just that you've got everything adjusted so that the beam pointer points to midpoint "zero" on the scale body).

So, would someone please let me in on the joke?

Y'all take care! Regan

[Whitespider]

Woodtroll,


...variances of .01-.02 grains...
1-2 HUNDREDTHS of a grain? :mrgreen:


But, let’s just think about this for a minute. A balance beam scale, any balance beam, uses geometry, gravity and a system of weights and counterweights. Because of the dynamics involved the beam is at its most SENSITIVE point when it is PERFECTLY horizontal. The most SENSITIVE position is also the most ACCURATE.

There is an easy way to test this. First zero the scale, than add a ½ grain weight to the pan. DO NOT adjust the counterweights, instead place a mark where the pointer is on the scale with the ½ grain weight. Next add another ½ grain weight to the pan (for a total of 1 full grain) and place a second mark on the scale. Now measure the distance between ZERO and the first (½ grain) mark, also measure the distance between the first (½ grain) mark and the second (full grain) mark. The two measurements will not be the same, because as the beam moves farther away from horizontal (level) it becomes LESS sensitive and therefore LESS accurate. If a balance beam scale is to be expected to give repeatability, it MUST be at its most sensitive (and most accurate) position.

If beam position didn’t matter we would/could zero our scales by moving a counterweight on the beam. But this isn’t the case, instead we zero by adjusting one end of the scale body up or down, because the beam NEEDS to be horizontal (level) to be accurate.

Sooooo...... the closer to horizontal (perfect level) the beam is, the more sensitive, accurate and repeatable the performance. And yes, I did in fact “tweek” my pan weight to “level” the beam (as it was about 2 degrees off level), but I didn’t actually [smilie=1: test performance before and after.

[joeb33050]

I suppose that I'm too serious about this stuff, maybe we need this kind of comic relief.
joe brennan


Woodtroll,


1-2 HUNDREDTHS of a grain? :mrgreen:


But, let’s just think about this for a minute. A balance beam scale, any balance beam, uses geometry, gravity and a system of weights and counterweights. Because of the dynamics involved the beam is at its most SENSITIVE point when it is PERFECTLY horizontal. The most SENSITIVE position is also the most ACCURATE.

There is an easy way to test this. First zero the scale, than add a ½ grain weight to the pan. DO NOT adjust the counterweights, instead place a mark where the pointer is on the scale with the ½ grain weight. Next add another ½ grain weight to the pan (for a total of 1 full grain) and place a second mark on the scale. Now measure the distance between ZERO and the first (½ grain) mark, also measure the distance between the first (½ grain) mark and the second (full grain) mark. The two measurements will not be the same, because as the beam moves farther away from horizontal (level) it becomes LESS sensitive and therefore LESS accurate. If a balance beam scale is to be expected to give repeatability, it MUST be at its most sensitive (and most accurate) position.

If beam position didn’t matter we would/could zero our scales by moving a counterweight on the beam. But this isn’t the case, instead we zero by adjusting one end of the scale body up or down, because the beam NEEDS to be horizontal (level) to be accurate.

Sooooo...... the closer to horizontal (perfect level) the beam is, the more sensitive, accurate and repeatable the performance. And yes, I did in fact “tweek” my pan weight to “level” the beam (as it was about 2 degrees off level), but I didn’t actually [smilie=1: test performance before and after.

[Woodtroll]

Whitespider,

I understand and agree with you completely about leveling the beam. What I couldn't understand is why everyone thought it was a joke. I thought maybe I was ignorant of some law of physics that everyone else had figured out, so that's why I requested a further explanation.

The .01-.02 variation didn't bother me as much as the comment about it being a joke. I guess I get used to folks making simple errors in notation (you see those kinds of honest mistakes a lot on these boards, as well as all kinds of intentional misspellings, shorthand, and abbreviations). I guess I just assumed you meant tenths of grains, and so I passed over that part completely as an honest error.

Thanks, y'all, for taking the time to reply. Regan

[joeb33050]

here goes.
"Because of the dynamics involved the beam is at its most SENSITIVE point when it is PERFECTLY horizontal. The most SENSITIVE position is also the most ACCURATE."
Who says so, how is accuracy affected if the beam, at zero, is not level?

"If a balance beam scale is to be expected to give repeatability, it MUST be at its most sensitive (and most accurate) position."
Who says so, why, how is repeatability affected if the beam, at zero, is not level?

"If beam position didn’t matter we would/could zero our scales by moving a counterweight on the beam."
If beam level mattered enough to care about, then beam balances would
have a level on the body,
have the beam, pivot, pointer and fiducial mark designed such that the beam would be level when the body is level and the pointer is at zero, and
have a nut and screw or another setup to make the adjustment to make that so

My 10-10 scale has a beam length of 5 3/4" from pivot to pointer. One degree in 5 3/4" is .100", 2 degrees is .201". A .5 grain difference on my scale is .190" on the scale. Then your 2 degree correction is roughly .5 grain. I got out my Stanley level and tried to figure out how I'd go about adjusting the weights under the pan. I think it can be done, but don't know how accurately.
As near as I can tell, my scale reads .5 grain = .190" high when level- if my level and my eyes are telling me the truth.

I suspect that nobody here knows how much repeatability or accuracy of a beam balance is affected by beam level at zero; and that nobody here knows if repeatability or accuracy is affected.

When you get into the weights under the scale pan, you're second guessing the scale manufacturer.

Until somebody comes up with some information rather than opinion, I'm sticking with my opinion that this is a joke.
joe brennan

[leftiye]

Joe,
Look at the old balance scales like the justice lady carries (probably doesn't help to be blindfolded- how can you operate the thang when ya can't see?).

When there's a weight difference the scale doesn't go straight up and down, it merely cants some. These types of scales are pretty much useless to measure anything quantitatively except only equality, but they do tilt to various amounts depending upon how much different the weights are. Therefore, if they aren't level, the weights on the two sides aren't equal.

Our reloading scales work on the same principle except the beam side of the balance is adjustable by moving weight further or nearer to/from the fulcrum (as opposed to adding/removing weight). When you crank the up/down thing excessively to zero the reading, the scale no longer reads perfectly accurately (the weight you will get will be different from the same setting when actually level). As said earlier, the dots in the pointer array are neither incremental nor ratio data. Though they are the same distance apart, they do not represent the same amount of weight. Sensitivity increases as level is approached. Repeatability is enhanced by sensitivity.

I know you would prefer an experimental proof, but all that I can offer you is that I know these things from experience (observations of empirical experiences).

[montana_charlie]

When you get into the weights under the scale pan, you're second guessing the scale manufacturer.
That was my concern.

The manufacturer knows how much each element weighs, and how it correlates with four other elements to provide an accurate reading when the scale is zeroed...and moving the adjustors a certain distance yeilds actual weight indications because other elements (beam-ends and pan assembly) remain constant.
Change any one of the 'constants' and everything else changes.

Yes, there is a screw on the bottom of the pan hanger that a person can 'screw' with, but did you notice there is also a screw that sets the position of the 'tenths adjustor'? Why not 'screw' with that as well...or instead?

Would 'messing' with one mess up the final reading any more that 'messing' with the other?

Changing either changes the 'balance' of the balance, as would grinding a little off the long end of the beam.
I guess that's why we trust the makers...instead of buying scale do-it-yourself kits to build 'em the way we like 'em?

Whitespider has a 5-10, so he can't perform this little test, but a 10-10 owner can.

Adjust the shot load in the pan hanger to get the beam level, then zero the scale.
Now, hang that brass weight on the peg which allows measurments up to 1000 grains.
The scale should still be zeroed if the adjustors are moved to '0' and a five hundred grain weight is placed in the pan. But, since the weight UNDER the pan has changed, I bet you won't see 'zero' at the pointer.

What Whitespider has is a scale that has dependably repeatable readings.
When he finds an accurate load, he can trust the scale to duplicate it at any time.
It will also show the difference (in dependable increments) between two charges.

But, he no longer knows the actual weight of any charge...and his increments of change are no longer (quite) in tenths of a grain (because the relationship between the pan assembly, short end of the beam, and the effect of the tenths adjustor as it moves along it's axle has all changed.)

If he added shot to the pan, his powder charges are actually lighter than scale markings indicate, and his charge weighs more than indicated if he removed shot.

So, if he says his favorite load is 7.4 grains of Unique, you can figure the weight of his charge, measured on your scale, will be somewhere between 7 and 8 grains.
CM

[shotstring]

I think this discussion is very interesting, and if we were trying to set up scales to accurately read to 1/10,000 it would probably be very important. Reloading scales are only set up for a "working" level of accuracy however, so to try and improve on it isn't really necessary in my book. A beam is more likely to be thrown off by worn pivots, dirt in the pivot area or bent beam points that it would ever be by the idiosycrasies of a perfectly level beam.

The simple fix to get it working at its best has always been to keep the pivot area clean and dust free, check with different size calibration weights when setting your scale up, and to repair parts when they are worn, which is free if the scale is RCBS. Other than that, just adjust the telescoping leg to get good readings on a given surface and you are good to go.

[Whitespider]

Who says so..........

Well joe, I don’t remember when or where I was taught the dynamics of a balance beam, but my guess would be high school physics. But, because I can’t remember where I learned it, I guess I have to say... I say so. And believe me, I really thought it was common knowledge.



If beam level mattered enough to care about, then beam balances would have a level on the body.....

Some beam scales do joe, and some have a level on the beam also. They cost a ton more than a reloading scale though.



When you get into the weights under the scale pan, you're second guessing the scale manufacturer.

Think about this. We’re not talking about a medical or laboratory grade scale. How much does an RCBS reloading scale cost? Heck man, it’s possible to spend more cash on a bathroom scale. We’re talking about cheap hobby grade scales here. If I tweak a mould or a reloading die, am I also second-guessing? Just because it’s a scale doesn’t mean a fella’ can’t “tweak” it to enhance performance.



Yes, there is a screw on the bottom of the pan hanger that a person can 'screw' with, but did you notice there is also a screw that sets the position of the 'tenths adjustor'? Why not 'screw' with that as well.......he no longer knows the actual weight of any charge.....if he says his favorite load is 7.4 grains of Unique, you can figure the weight of his charge, measured on your scale, will be somewhere between 7 and 8 grains.

No charlie, I didn't "screw" with the screw. The screw merely allows the disassembly of the hanger to gain access to the pan hanger weights. These scales are not calibrated to exact tolerances, they are more or less mass-produced. I’m sure the scale was within tolerances as it was produced, just not perfect. By changing the pan weight, I merely adjusted the scale beam closer to its optimum setting (absolute level). Calibration is different, and would be affected by “screwing” with the screw on the 'tenths adjuster' counterweight. This screw is used in conjunction with “check weights” to adjust (or calibrate) the scale. I’ve checked my scale several times with “check weights” of different manufacturer, when my scale reads 7.4 grains of Unique, it is in fact correct.

[Whitespider]

:veryconfu Perhaps I should clarify a bit further.

Changing the weight of the pan to adjust “level” of the beam does not affect the “calibration” of the scale. Adjusting one end of the scale “body” can still zero the scale.

But, moving counterweights to adjust calibration will affect beam level at zero. Adjusting calibration in this manner will require beam “level” to be readjusted. The RCBS 5-10 and 10-10 scales can be calibrated by moving the entire “tenths” counterweight assembly on its screw, requiring adjustment of beam “level” by use of the pan weights.

It is important to understand the difference. Changing the pan weights to adjust beam “level” does not “move” the geometric relationship of pan to beam, hence, no calibration change. But, moving the counterweight in relation to the beam is geometric, resulting in a calibration change.

[Pat I.]

Joe,

Since it sounds like Whitespider actually knows what he's talking about if I were you I'd quit arguing with him, you might be in over your head!:-D

Pat

[twoworms]

I have a RCBS 10-10 thats about 20 years old, it still works better than I do... :)

Just keep it clean, zero it on a solid bench, keep the blowing air to a min and check every thing 2X before loading a single round.

Tim

[Woodtroll]

I hesitated to post for more information here, when I asked for someone to let me in on the "joke", but now I'm glad I did- I've learned a lot.

I think it's poor form to dismiss someone's comment as a joke, and then follow up later on with an "Oh yeah, says who?" when presented with the reasoning. I'd a whole lot rather see an explanation in the first place as to why you think something is not right, than to waste time with a flippant "think about it" as if the answer should be obvious to everyone who isn't an ignoramus. In this case, it was not a joke, was it? And I thought it was elementary physics that a balance beam operated most precisely when it was zeroed with the beam level. Over the years, foreign matter can accumulate and change the relative weight of components, which could certainly be adjusted just as Whitespider described. I don't see that as tampering with the inherent design of the mechanism.

It is often hard to tell folks' intentions or "tone" from the written word on these internet boards, so I'm sorry if this discussion I stirred back up has offended anyone. I do appreciate the fact that we can learn so many diverse things here, and can usually discuss them (including differences of opinion) as true gentlemen should.

Thanks for the conversation, Regan

[David2011]

I did the same thing Whitespider describes several years ago to my RCBS balance. I always had to extend the leveling screw a long way to get it to zero because there was too much weight under the pan. I just put all of the shot in the powder pan along with the removed parts. I put the leveling screw in a position that made the balance close to level and removed various sized pieces of shot until I had it zeroing in a reasonable area. When satisfied I reassembled the weight cup. It is definitely not an adjustment screw. It will not cause the balance to read heavy or light but it did make it easier to use.

[montana_charlie]

No charlie, I didn't "screw" with the screw. The screw merely allows the disassembly of the hanger to gain access to the pan hanger weights.
I knew that, Whitespider. I was just having some fun with words while saying what was on my mind.

But, lets 'argue' for a bit about those 'hanger weights'.

If you ended up removing one of them (pretend you did) to get your beam level, couldn't you have achieved the same effect by filing a little off of the pan hanger, itself?

I'll pretend you said 'yes'.

What about filing a tiny bit off of the beam, right where the pan hanger attaches?

Still 'yes' I'm guessing.

Now, if you had added a piece of shot instead, couldn't you have gotten level by filing a bit off of the copper blade on the long end of the beam?

I am going to imagine you saying 'yes' in a suspicious tone of voice.

Sure, these would have been permanent (as in 'irreversible') changes, but if you no longer have the same shot pieces that were originally in the pan hanger...the change you made is also 'permanent', isn't it?

Now I see you not answering 'yes' or 'no'...just leaned back with your arms folded, waiting for me to finish.

If filing pieces off of the beam, or from parts attached to the beam, gets the same results as changing shot...how is changing shot different than modifying the beam.

And...if you modify the beam...can you expect the counterweights to still have the same relationship with it (the beam) that they had in the beginning?

Sure, these are hobby-quality scales, designed to provide hobby-quality accuracy while weighing hobby-quality gunpowder. Since they are only blessed with hobby-quality precision, I think it's a mistake to make hobby-quality changes which can affect hobby-quality explosions.

Just my hobby-quality opinion...

Your background may give you the expertise...along with the quality of your check weights...to make changes that meet a higher than hobby-quality criterion.
You certainly have every right to do so.

But I think you should mention any changes if you ever sell the scale.
CM

[leftiye]

Charlie,
I very much respect your opinion on many of the threads where we've enjoyed deep thought, and varying opinions, and I've learned much from you. You are waiting for the but? I feel that whitespider not only is correct, but that he's given us a pretty good outline as to how to improve the accuracy and functioning of our mechanical scales. I do believe it to be fundamental that the beam should be horizontal for best sensitivity, and accuracy. I also think white spider is right in saying that this leveling in no way affects the accuracy of the weight measured in terms of making it weigh incorrectly. So long as everything is set at zero, leveling the beam should not change the actual results weighed.

Joe, if you want to check this simply weigh the same weights before and after leveling the beam, or check it before and after against a digital scale.

I want to thank everybody for supplying this thread where valuable knowledge has come to light. At least I learned something that I feel to be of value. The Bible may not be open to adjustment, but a mechanical scale is in no way beyond thoughtful improvement.

[joeb33050]

Well, it's subject to analysis.
A scale works thus:
Sometimes the beam is level
It's a lever, with W weight and L length on each side.
Left W X L = Right W X L and the beam balances
Add a little weight to the Right side and the beam balances, Left side high
It balances = stops moving because Left L X W = Right L X W again
But, but, but, the Left and Right halves didn't change length!!!
Yes they did
The lengths, the Ls, aren't the measured lengths of the sides of the beam, from pivot to end.
The lengths are the EFFECTIVE lengths of the beam sides
The effective lengths are:
imagine a horizontal line through the pivot
imagine the beam horizontal, effective length = measured length
add some weight to the pan, the left side of the beam goes up
drop a line perpendicular to the imagined horizontal line through the pivot, from the end of the left hand beam side
the higher the beam, the more right goes that perpendicular line and the shorter is the distance from pivot to intersection
the shorter is the effective length of the beam half, and the right hand beam side is also getting shorter
if the left beam side could get to 10:30 that's 45 degrees and the ratio of measured beam half length to effective beam half length is the square root of two to one
since the left hand beam half is longer than the right hand, while both get shorter on deflection, the left gets more shorter than the right
and deflection is caused by putting weight in the pan
so Left L gets shorter, W stays the same, Right L gets less shorter and W increases
so that again, at some angle, Left L X W = Right L X W

Now, if you like that so far, think about this:
Moving the heavy weight on the left hand beam half, in or out, and moving = turning the tenths/grains wheel on the right hand beam part, change the (are you ready) the EFFECTIVE LENGTHS.
Have to go shooting now.
Pat, how is this, is it clear?
joe brennan

[Pat I.]

Pat, how is this, is it clear?
joe brennan

HUH, WHAT! Oh sorry Joe I nodded off there for a minute.

Yep, clear as frosted glass.

[felix]

Joe, you have just begun in this analysis. How far do you want to take it? I bet you have heard about drugs being manufactured in space, or in a zero gravity arena. For your assignment today, see if you can surmise why this is so. ... felix

[sundog]

For almost everyone other than world class BR shooters scale performance is relative.

Sensitive enough to detect a 1/4" square of bond paper dropped in the tray

Accurate enough to come at least close to matching up with a check weight

Repeatable enough so next session will produce like results or like results are repeated with a check weight

Adjustable enough to hold a good zero

About adjustment. Ballast add or subtract (if the scale has ballast) should be a much preferred way of adjusting to zero instead of removing material from the tray or beam. After all, that's what ballast is for. Kinda like doing CG on an aircraft. You wouldn't want to grind a little off the nose or tail. Would you?

Besides, if talking about weighing powder, it seems that volume is just as or more important than charge weight. That could a whole other discussion in and of itself.

[montana_charlie]

Charlie,
I very much respect your opinion on many of the threads where we've enjoyed deep thought, and varying opinions, and I've learned much from you. You are waiting for the but?

I do believe it to be fundamental that the beam should be horizontal for best sensitivity, and accuracy.
Thanks for the kind words, and I have some for you.

I will concede that you, and Whitespider, may be correct in believing that the best position for a zeroed beam is perfectly level.
But, with no confirmation from the manufacturer, I hesitate to accept it as the logical truth that it seems to be.

The discussion is actually academic, so far.
While I am convinced that Whitespider's scale no longer reads weight the same as it did from the factory, I think the amount of change he caused falls so far to the right of the decimal point it doesn't actually matter. Not only do I think his change was too small to be significant, the improvement (if any) is too slight to be detectable...except for a 'visual satisfaction' in seeing a level beam.

One might ask (academically), "What is the chance that a scale can be improved beyond it's state when it left the factory?"
Most of us, considering most things manufactured today, would say there is often quite a lot of room for improvement.
So, a (hobby-quality) scale can probably benefit from some judicious tinkering.

If RCBS were to put out a newsletter...or a former employee was to tell us about working at the 'beam tweaking' station...we might learn that there is a 'tolerance' which allows the tweaker to call it good enough if he can quickly bring the beam within (say) plus or minus two degrees of absolutely level by adjusting the pan hanger ballast.
With that knowledge, we could all then start splitting hairs (actually splitting shot pieces)...knowing that even the manufacturer thinks that 'level' is best...and doing our level best to get level beams.

Without that factory confirmation, we are floating around in our academic discussion about whether 'screwing' with shot fundamentally changes a scale...or not.

I still believe it does, but (after further reflection) not enough to matter. However, I will concede that the change might constitute an improvement.

As for anyone being in over his head, I might be on tiptoe to catch a breath, but I think Joe is in no danger of drowning, Pat.

CM

[leftiye]

Charlie, and this pretty much answers Joe's last "analysis" (no slight intended, to identify post only).

I think you've hit the nail on the head with saying that the actual change in actual weighed weight is miniscule. Joe, this also goes for "effective lengths" of the levers (beams). The actual shortening of the beams (even if measured relative to each other) is probably not measureable, or infinitesimal if measureable. Remember that the balance beam (with weights) is 4 or 5 inches long and the difference in effective length would be way less than 1/64" when zeroed. The extreme angle of "bottoming" or "topping" out the beam is only a degree or two, and the actual angle of the adjustment way less than a degree probably.

But the adjustment should still be worthwhile maybe in terms of sensitivity (plus remove the magnets). Maybe the most valuable result is only the perception that the scale is "right." And - yup they do already measure in "tenths."

[montana_charlie]

Charlie,
I think you've hit the nail on the head with saying that the actual change in actual weighed weight is miniscule.

Maybe the most valuable result is only the perception that the scale is "right."
Now YOU have hit the nailhead, I suspect.
Should we hire out as carpenters?
CM

[joeb33050]

I'm back from shooting, learned a lot today. Back to the scale.
The effective length of a side of the beam is really the center of gravity of the arm to the pivot. Cut the arm off, find the balance point, measure from the pivots and that's the effective length. The effective length is the length of a zero mass beam half with a weight at some point. Like those pictures of levers, with pivots and weights and zero mass arms. The scale is more confusing because we put stuff in the pan, turn that wheel thing and move the big left hand weight along the teeth on top of the beam.
My scale LH is 5.862" and RH is 2.412", but I can't go from these to any other numbers because I don't know the weights of the sides of the beam, the weight of the big weight on the left and all about the weight and screw pitch of the round adjuster thing. And I'm not going to take the scale apart, or cut it in half.

So, if you draw a horizontal line with a pivot-looking thing on it, and a line from the pivot going up toward maybe 10:00, and a line down perpendicular to the first line, from the end or any point on the 10:00 line, you will have constructed a right triangle. We'll call the 10:00 line the BEAM LENGTH, you will note that the horizontal line from the pivot to the perpendicular line is SHORTER than the B.L., this is the EFFECTIVE LENGTH, let's call this the E.L.
If we divide the E.L. by the B.L. we get a number that varies according to the angle. Somebody decided to do this, and called the result the Cosine. Then he figured out values of the Cosine for various angles.

Let's say we start with a level beam and put weight in the pan to make it go up 2 degrees. The beam half length stays the same, nicht war? The E.L. goes down. How much? By 1-the cosine, that just happens to be .99939. So the E.L. is 99.939% of the B.L. Subtract from zero and get .00061.

Let's zero the scale at that 2 degree elevation, then add weight to make the beam go up another 2 degrees. Cos goes from .99939 to .99756, subtract and get .00183.
So, the scale is more sensitive from level to 2 degrees as it is from 2 degrees to 4 degrees. If the beam length is 10", it goes from 10-.00061=9.99939 to 10-.00183=9.99817. This has to do with the shape of the cosine as angle varies.

So, the beam moves more for a given weight addition if it starts off level. The pointer moves more. Then we move weight to zero the scale.

I can't make the scale zero at different weights as we go from level to off level. Nor can I make it repeat differently at level and off level. Nor can I make it differ across the range off level and level.

I can make the scale become less sensitive, but not less accurate, repeatable or linear.

What have I missed?
joe brennan
(There are two mistakes in the above.)

[floodgate]

Just to pick ONE MORE nit, it's "minUscule", not "minIscule".

And exactly 126,098.3 Angels can dance on the head of a pin.

"A pedant ain't nothing more than a stepped-on piss-ant."

floodgate

[Whitespider]

WOW, and I do mean WOW!

I hesitate to add more to this discussion because a goodly share of it has gone beyond my comprehension and training in physics and geometry. I also hesitate to post the following, because I fear I’ll be taken less seriously. All the same, here goes..... Just to be honest with all involved, I dropped out of school at age 16 because of shear boredom. I am, in all practicality, self-educated.

joe mentions there are two mistakes in his last post, I have no clue what they are. In fact, I’m simply confused by his E.L., B.L., COS. and......... I’m not sure what it has to do with leveling the beam and I believe it ignores two important facts;
1) The beam itself has weight and is part of the weight/counterweight system.
2) The beam is brought back to the zero position in order to “read” the weight, effectively negating the CHANGING E.L., B.L., COS. and.......


charlie talks about filing material from the beam itself to level the beam, indicating it would accomplish the same thing as modifying the hanger weight. One place he advocates this removal is right at the hanger point of the beam. Hmmmmm....I’m having a bit of trouble reconciling this with my knowledge of physics and geometry. It may work at that exact point on the beam, it may not, I’m not sure. My gut tells me that the beam itself is the one thing that MUST remain constant.

I am sure that modifying the beam weight at any other location (except the exact pivot point) would be equivalent to changing the geometric relationship of weights/pivot/hanger. This would than require an adjustment to calibration, which would change the level at zero. So more material would have to be removed from the beam to regain level, which would require calibration, which would require leveling again, etc., etc., etc. In theory this would continue indefinitely, but in reality one of three things would happen first;
1) At some point the scale could no longer be accurately calibrated.
2) At some point you would run short of beam material to “file” away.
3) At some point you would give up and modify the weight of the hanger to level the beam.


And yes, everything we’re talking about is minUscule! But it’s still fun ain’t it.

[leftiye]

Joe (did I miss something?),
All I can see that you might have paid attention to that I didn't see you say is - that the effective length is way shorter than the whole beam, and that the shortening when angled from the horizontal is therefore something like half as much as when you figure the one or two degrees from horizontal with the whole beam. Therefore something like .005" or less. However, I thank you for "proving" that the beam is more sensitive when horizontal (it takes less weight to move it the first 2 degrees & etc.). I just gotta say that it's still miniscule (that's how I spell it, so there).

[montana_charlie]

charlie talks about filing material from the beam itself to level the beam, indicating it would accomplish the same thing as modifying the hanger weight. One place he advocates this removal is right at the hanger point of the beam. Hmmmmm....I’m having a bit of trouble reconciling this with my knowledge of physics and geometry. It may work at that exact point on the beam, it may not, I’m not sure. My gut tells me that the beam itself is the one thing that MUST remain constant.
My object was to point out that the beam, the moveable weights (when they are in their zero positions), the pan, it's hanger, and even the little wire loop the hanger hangs from...all exist (along with the shot pieces) in an all-inclusive 'environment' that results in a 'zero grains' reading on the scale.

The shot pieces, along with the pan, hanger, and wire loop (and it's pin) form an assembly that exerts a given amount of predetermined downward force (weight) at the point on the beam where it all hangs. Making the 'assembly' lighter, would be the same as making the 'beam' lighter if the modification was done at that exact point.

Changing the downward force at any point along the beam changes the whole environment to some mini...er...micro...err... infinitesimal degree.

But it’s still fun ain’t it.
Brain exercise is usually healthy...and sometimes fun.
CM

[joeb33050]

When we model levers we assume that the lever has no mass/weight and has weights attached at some point. This for the simpler analyses. Any lever can be thought of this way, so also the scale.
Say there's a beam that weighs 1 ounce per inch on the left side and 2 ounces per inch on the right side. A 10 inch left side would be represented, for analysis, as a 5 inch zero weight beam with a 10 ounce weight at the end. The right side, to balance, would be 5 inches long because 5 X 2 = 10. It would be represented, for analysis, by a 2 1/2 inche zero mass beam with a 20 ounce weight on the very end. Or a 5 inch zero mass beam with a 10 ounce weight on the end. Or a 20 inch zero mass beam with a 1/2 ounce weight. Any combination on either side, as long as the Left L X W = Right L X W for it to balance.
The beam weight or length does not have to remain constant, in fact the beam weight and effective length are what is changed when moving weights, adding stuff to the pan or turning that round thing. As the beam moves up or down, the effective length gets smaller.
I don't know what else to say, and still believe that the contention that a scale beam that is not level at rest causes inaccuracy and unrepeatability is
A JOKE.
joe brennan

[BABore]

One little item I didn't see anybody bring up is the 0.1 gr resoulution rotary or tab scale verses the main 10 gr resolution scale.

When weighing out incremental charge weights for test loads, say your increments are 0.5 grs and your starting at 28.5 grs. When your at 29.5 grs and have to go to 30.0 grs, you have to make a choice. Do I increase the tenth gr wheel to 10.0 grs plus the 20 grs on the coarse bar, or do I roll it back to zero and slide the coarse bar to 30 grs. Does it make a difference?

Sure did on my RCBS 5-10 scale. There was a 0.15 gr difference. Is it a big deal? Not really, just keep good notes of how you set it. It's definetly something that should be verified and be aware of when working up loads where 0.1 to 0.2 grs can make a difference. I checked my scale at several weight intervals to confirm if the difference was consistent.

[montana_charlie]

still believe that the contention that a scale beam that is not level at rest causes inaccuracy and unrepeatability is A JOKE.
I have bought into it, Joe.
I reached back to the beam balance where you start with a known amount of stuff in one 'pan', and add stuff to the other until they hang even. That has been used to weigh out jewels, food, and justice since mankind started making rules.

I'll accept the idea that the level beam is the 'proper' beam for the same reason I believe all zebras should have an odd number of stripes. It just seems like an 'orderly' (well balanced?) state of being.

But, just as I don't carry black paint when approaching zebras, I am not going to modify my 10-10...all joking aside.
CM

[joeb33050]

One little item I didn't see anybody bring up is the 0.1 gr resoulution rotary or tab scale verses the main 10 gr resolution scale.

When weighing out incremental charge weights for test loads, say your increments are 0.5 grs and your starting at 28.5 grs. When your at 29.5 grs and have to go to 30.0 grs, you have to make a choice. Do I increase the tenth gr wheel to 10.0 grs plus the 20 grs on the coarse bar, or do I roll it back to zero and slide the coarse bar to 30 grs. Does it make a difference?

Sure did on my RCBS 5-10 scale. There was a 0.15 gr difference. Is it a big deal? Not really, just keep good notes of how you set it. It's definetly something that should be verified and be aware of when working up loads where 0.1 to 0.2 grs can make a difference. I checked my scale at several weight intervals to confirm if the difference was consistent.

I'm surprised. During the ASTOUNDING POWDER MEASURE TEST, and at many other times, I've had to decide whether to use big weight at a ten grain increment, ex 130 grains, and the right hand screw thing at 0; or big weight at ex 120 and the small right hand screw thing at 10. In every case, when I zeroed the scale with ex 130 grains in the pan, both methods were exactly = very close to the same.
It looks like another test is required.
joe brennan

[leftiye]

Plus one as to what Charlie said. But the whole thang started losing that white knuckled imperative when the differences were shown to be possibly too small to calculate. Though I might still figger out a way to level my beam accurately just for the heck of it!

[joeb33050]

One little item I didn't see anybody bring up is the 0.1 gr resoulution rotary or tab scale verses the main 10 gr resolution scale.

When weighing out incremental charge weights for test loads, say your increments are 0.5 grs and your starting at 28.5 grs. When your at 29.5 grs and have to go to 30.0 grs, you have to make a choice. Do I increase the tenth gr wheel to 10.0 grs plus the 20 grs on the coarse bar, or do I roll it back to zero and slide the coarse bar to 30 grs. Does it make a difference?

Sure did on my RCBS 5-10 scale. There was a 0.15 gr difference. Is it a big deal? Not really, just keep good notes of how you set it. It's definetly something that should be verified and be aware of when working up loads where 0.1 to 0.2 grs can make a difference. I checked my scale at several weight intervals to confirm if the difference was consistent.

The RCBS 10-10 scale can be adjusted in 10 grain incrememts in two ways.
First, we can put the left hand big weight at 10 or 20 or 30 or ........., and keep the right hand rotating cylinder thing at zero.
Second, we can set the left hand big weight at zero and the right hand thing at 10 = 10 grains, or the left hand weight at 10 and the right hand thing at 10 = 20 grains, or the left hand weight at 20 and the right hand thing at 10 = 30 grains, or.........
A poster on Cast Boolits reported that his scale read different weights with the two ways of setting the scale.
I cranked up the 10-10 scale to see if it did the same. First using the left hand 10s and right hand 1s weights; then using only the 10s weight. Here are the results:
10 = 10
20 = 20
30 = 30.1
40 = 40.1
60 = 60.1
80 = 80
100 = 100
This test took a while, a lot of zeroing was going on, and adjustments, and deciding about less than tenth grain differences. As shown, this is as close as I could call the readings, but in every case there was a difference of less than a tenth of a grain- the X0-X0.1 readings were closer to .1 grain than to .0 grain.
joe brennan