Accurize a balance beam scale?

DaveT said:
Guys, mike in co is the smartest man in any forum in the entire universe. In another thread "he" determined and told us all that our chargemasters are basically bathroom scales disguised as loading scales. And he talked down to us while telling us our tools are just junk. I try to just stay out of this stuff but it's just hard....
Dave T
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it is the internet! LOL
 
The trouble with this thread's title is, it should really say, "Getting the most out of a balance beam scale". Now, beam scales are capable of being very accurate. The ones we buy for $50 for reloading are extremely accurate, but, in comparison to the ones for $5000, they are not quite so accurate.

A $50 beam scale in absolutely perfect working condition will resolve every bit as close as todays $1000 scales. It will be slower by a margin that will drive folks like me away.

Todays $175 scales, work as well as 2 years ago $1000 scales.

Unless you are overseas, and then, spend more and forget the difference.

Electronic scales are most valued for their speed, not their accuracy. All scales have mechanical limits that we regularly beat our heads against when using high precision scales. Dust, cat hair, static, airflow, vibration, all things that can cause headaches when using any scale, don't just limit this to electronic ones. When you get to where an above mentioned error doesn't bother you, your scale isn't sensitive enough.

At the end of the day, every shooter has to determine if the scale is a determining factor in their group sizes. If it is, then changing scales is mandatory before improving their shooting. If it is not, then perhaps throwing charges is adequate for the shooting platform they use. Unfortunately, nobody here can determine that. Only you know what's best for you.
 
i dissagree with nearly eveything 4mesh said...
with the exception of this one line:

At the end of the day, every shooter has to determine if the scale is a determining factor in their group sizes.

reloading beam scales are advertised at plus or minus 0.1...
br powder throwers with n133 throw at plus or minus 0.2-0.3
reloading electronic scales are plus or minus 0.1 and some will not resolve trickling.
using a electronic lab scale one can easily reload to plus or minus .03.
so yes ACCURACY is a major benefit of A BETTER ELECTRONIC SCALE.

they are 10 times(.03 vs .3) more accurate than thrown charges of n133...think about that on those days were one shot is a little out or the group is just a bit larger than you had hoped for.

mike in co
 
jackie schmidt said:
I tested a Chargemaster against my Denver Instruments TP-153, and +- .1 is being generous.

It seemed that the less "trickling" the Chargemaster did, the more consistant.......jackie
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Jackie,

I have a Charge Master and I definitely agree, +/- 0.1 is being generous. I use mine to pre-throw charges because it's so fast to set it up. I dump the results on my 10-10 and trickle to weight. I'm seldom waiting for the CM.

The CM does best with the spherical powders, which are the same ones that work great in a measure, so it works best where it's least needed. I'd really like it if it worked well with 4350 or 7828, but it's not good with them at all - they clump and dump giving more like +/- 0.2 or 0.3.

The 10-10 is repeatable enough for my hunting ammo. I try to reduce "accuracy" (hitting a specific charge weight) as a variable by setting it up using check weights to set the pointer at the nearest 0.5g to the charge weight I'm going to be weighing, then adjusting the vernier to the actual weight. I've had the 10-10 for at least 2, maybe 3 , decades, it damps really quickly, and is much more repeatable than the Redding Scale I have.

I'd buy one of those rather expensive digital scales but I don't think it would let me shoot any better than I do now. Power charge accuracy isn't the tall pole in my accuracy tent.

Fitch
 
i have mentioned this before, and still see peoople trickling up without bumping the beam to get a solid movement.

Definition of HYSTERESIS
: a retardation of an effect when the forces acting upon a body are changed (as if from viscosity or internal friction); especially : a lagging in the values of resulting magnetization in a magnetic material (as iron) due to a changing magnetizing force.

in magnetic dampend scales...the beam lags...alot when trickling small kernel powder.....so bump the beam to get it to move and the resettle.

MAY not be as big an issue with large kernel powder......

mike in co
 
Mike,
I think that the damping only exists if there is motion. Obviously, copper is not magnetic. The force, that damps the beam occurs when the conductor moves relative to the magnetic field, and I think in proportion to the beam's rate of swing. This amounts to a variable damping that diminishes to about nothing. I think that this may illustrate what I am referring to. http://www.youtube.com/watch?v=ZCs0Y7HH2zA&feature=related
 
boyd....he is using varget a large kernel powder////so yes it will show every change......
try this with one kernel of 8208 or ni33....
two...
it one was to add a sereis of marks...a scale to the area his pointer is at, one might actually be able to calibrate for large kernel....
i have seen my own beam scales not move when adding enought time to know this happens
the copper is a conductor moving thru a magnetic field...it resists movement.

mike in co
 
here is a test you can do at home.
put aprox 30 g of small kernel powder in the pan and weight it.....( n133, 8208...any fine ball powder)
what ever it weighs, move the 1/10 up one , touch the beam and let it settle....
it should be aprox 1 mark low.
once it has settled trickle in powder without touching the pan/beam.
once you have trickled up the one mark and are now at zero(mid mark), touch the beam get it moving and see where it settles.
i can nearly guarantee thet the average beam scale with small kernel powder will now have its pointer ABOVE the middle mark.
your trickled up charge is actually heavier than the scale told it was( if you never bumbed the beam).
mike in co
ps do not come back and tell me how great it works with 4895 or varget or any other large kernel powder.
 
What do you figure a grain of Varget weighs? Perhaps that is a good as it needs to get. While we are at it, how many grains of 133 to a grain of varget?
 
since you asked
varget is aprox 0.017 per kernel,
oem 8208 is aprox 0.004 per kernel.
2001 n133 is aprox 0.01 per kernel...but there are inconsistancies in the kernel size.

what this shows, what i have said since day one...the significance in weight.....
oem 8208 meters very well due it its very small size and consistancy.
n133 does not as it is 2.5 times the size of oem8208....
and the issue with beam scales shows up in the diff of varget and oem8208 or n133.
in the case of oem8208 varget is FOUR times the weight per kernel, and 70% heavier than n133.
mike in co
 
Thanks for the info. I had no clue. It prompts a question. If the better electronic scales, that see reloading use, read to .02 grains, and a tuned up balance will show a single grain of powder (Varget) that weighs slightly less than that, why isn't a tuned up balance good enough for any reloading task? I know that for any given number, an electronic scale is likely to be more correct, when compared to a standard, but since each of us (who load using a scale) is usually working with the same scale for all of our load workups and loading, the main issue, other than gross errors, is consistency, which I believe has been achieved, in the case of tune-ups that have been properly done. (not to be taken for granted, but proven by testing) My scale has not reached my goal for its performance, but it is a whole lot better than when I started working on it, and I have not finished. It has turned into an interesting project.
 
DSM said:
I have an old RCBS 505 scale that I want to accurize. What are the tricks in making a balance beam sensitive to one granual of powder?
Click to expand...

Meanwhile, back to the original posters question: Does anybody have an addition to list of things that langnc and Jackie posted that can be done to turn up a balance beam scale?

Thanks
Fitch
 
Clean and don't oil the agates that the knife edges sit on. Sharpen the knife edges so that when you look straight at the edge there are no visible shiny spots, and then burnish the edge with the side of a mechanical pencil lead. Spread the wire bail that supports the pan holder so that it can not shift from side to side on its knife edges, but does not press against the abutments at their ends. Level the base of the scale by pulling material from the cavity in the pan hanger and then adding small bits to the pan till the beam pointer is perfectly aligned with the center mark of the scale (with the base level), and then add the material to the hanger cavity. Borrow or buy a set of check weights, and check the accuracy of the scale at several weights. Consider if the main sliding weight needs adjustment. If it needs to be increased, this can be done with paint, and fine adjusted by scraping. (An easier way is with Scotch tape. leaving a tab sticking out to trim for fine adjustments, buy cutting off small pieces, and then sticking it down.) If your scale has a built-in plastic cover, consider not using it to avoid a static charge. I now store my 10-10 in the cardboard box that it came in, with a sample of "Formica" in one end, so that I can leave the leveling screw down, without punching a hole in the box, over time. Practice with a fixed weight to learn the tricks of using the scale so that it does a better job of repeating. (electronic scales have their own set of tricks, so this is not unique to balance scales.) Another thing that I have not done, is to mount a needle on the pointer scale (doesn't affect the balance of the beam) to make the scale easier to read. I have an inexpensive USB webcam that I use to project the image of the end of the pointer and its reference scale onto my computer monitor. If I remember correctly,it cost about $35. I have also figured out how to throw charges into the scale pain, with it on the scale, without powder bouncing out. With this setup I can shave a little off the time that it takes to throw and trickle a charge. The last frontier is the pan hanger hanger (the bent wire piece) if I can make it more stable on the knife edges, I will truly be finished.

I might point out that like fellows that have opinions on tuners, that have never used one, those who have never attempted a full tune-up on a balance are only speaking from assumption and conjecture...which is of course their right.:)
 
i did h4831 today....
0.044.....
even heavier than varget...close to 1/2 a tenth.....so one would expect a scale that was plus or minus .1 to notice it...
like i said big diff depending on powders kernel size.
mike in co

mike in co said:
since you asked
varget is aprox 0.017 per kernel,
oem 8208 is aprox 0.004 per kernel.
2001 n133 is aprox 0.01 per kernel...but there are inconsistancies in the kernel size.

what this shows, what i have said since day one...the significance in weight.....
oem 8208 meters very well due it its very small size and consistancy.
n133 does not as it is 2.5 times the size of oem8208....
and the issue with beam scales shows up in the diff of varget and oem8208 or n133.
in the case of oem8208 varget is FOUR times the weight per kernel, and 70% heavier than n133.
mike in co
Click to expand...
 
I recall hearing that the scale arm should be dismounted when not used so that the metal damper isn't kept in the field of the magnets.
 
john,
the metal is copper...nonmagnetic, but will conduct a flow.
so in the field of the magnets is not an issue...it is movement within the field that is dampened by the magnet.....
but there is still the resitance to change. the beam is in a happy state when not moving..it likes it there...it is when you add a kernel of powder and try to move the beam( and the copper dampener) that one is fighting the magnetic flux that is in a happy state with the copper dampener....movement in the field is work, and the beam resists changing(hysterisis) in small increments.
mike in co

John Kielly said:
I recall hearing that the scale arm should be dismounted when not used so that the metal damper isn't kept in the field of the magnets.
Click to expand...
 
John Kielly said:
I recall hearing that the scale arm should be dismounted when not used so that the metal damper isn't kept in the field of the magnets.
Click to expand...

Like many things one hears, that happens to be not true. The damper is a piece of copper. It is totally non-magnetic and can't be altered by static magnetic fields. It can sit there motionless forever (in practical terms) and not be degraded in any way by the magnetic field.

The damper works because it is a conductor of electricity being moved through a magnetic field. When the conductor moves in the magnetic field of the damper magnet it generates internal currents that flow within the piece of copper and are dissipated in the coppers internal resistance as heat energy - i.e. it warms up the piece of copper. (Not to worry, the energy involved is miniscule, the mass and heat radiating surface of the copper large - it not only won't melt, it's such a small temperature change it would be a challange to measure it). The damper works by taking taking energy out of the beam and dissipating it as heat in the copper.

The damping effect occurrs because generating the currents requires work which is manifested as a force opposite to the direction of beam movement. It is this force that performs the damping action because it is always opposite to the direction of motion of the balance arm.

The currents, and therefore the damping, are proportional to the velocity of the conductor in the magnetic field (v X B), which means porportional to the speed of balance beam movement. No motion means there is no force. Very slow motion means very little damping force. In theory, if the bearings are perfect, the damper being friction free will have no effect on the steady state accuracy of the scale. It will have an effect on how long it takes the scale to come to equilibrium (balance).

So if the bearings are either perfect or really really good, the scale will respond to one kernel of powder being added, but it may take some time for it to move to that new balance point - one has a very small imbalance force (the weight of the powder kernel) trying to move the beam which has mass and inertia that are quite large by comparison to a powder kernel, and a damper that will resist the movement with a very small force since the velocity of the beam is really really slow in response to this tiny imbalance force.

The tiny force and mass of the beam determine how long it will take to respond. It will take longer with a magnetic damper, but it should give the same reading as it would without the damper, if one waits long enough. The mass of the beam will also have an effect. A heavier beam will have more inertia and thus take longer to move.

Fitch
 
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Fitch,
Such well done and comprehensive explanations are rare, and it matches perfectly with my observations.
Boyd
 
small grains of powder...very small force to try and move the beam........
i see no one has responded to my balance beam challenge.
the force is so small and the knife edges are not perfect...the beam does not move...not enough force to over come the resistance to change....
the world is not perfect....
go look at my list of powder weights by kernel.......how long for the real wworld beam to respond to single kernel of oem 8208 ??


mike in co
 
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