Loading some ammo recently on my RCBS Chargemaster and got tired of chasing the tare. So I set the charge to .2 grains under the weight I wanted and pulled out the Ohaus 10-10 to trickle up the charge to the correct weight. After a couple of loads I placed a trickled charge back on the RCBS scale and found I had .5 grains over the proper charge. Repeated this several times and the charge was never correct. So I got to thinking about what was wrong with the Ohaus and the best I could figure out was that the magnetic dampening was holding the balance bar and not letting it react to the powder that I was trickling into the pan. I'm thinking about taking the plate that reacts to the magnet off and trying again. Anyone else ever have this issue with a magnetic dampened scale?
scales and magnetic dampening
- Thread starter clowdis
- Start date
I recall that Lee had a challenge to test a scale for "stiction". They suggest to cut up some squares of regular computer printer paper to 5/16" x 5/16". Zero out your scale and wait for it to stop. Carefully put one square of paper in at a time and count the number required to get the scale to first move. They claim each square is 0.1 grains, and a good scale will move on the first piece added.
I would test both your balance beam and digital to be sure which one is the bad actor...
BoydAllen
Gold $$ Contributor
It is pretty common that shooters have no clue about how magnetic damping works. When a conductor (the copper blade on your scales beam that you are considering removing) is moved through a magnetic field, within the conductor, eddy currents are generated, as well as a magnetic force opposing the field through which it is moving. The key word here is moving. When the beam is not moving, no eddy currents are being generated, no magnetism is generated. The magnets exert no force on the scale beam. Look elsewhere for your problem. Give RCBS a call, your scale is under lifetime warranty. They will send you a shipping tag so that you can send it to Ohaus for service or repair. I would get into how to tune a scale, but I think that this is your best option.
What he said...it is NOT the magnets.
Hi Boyd,
Could you give us some advice on how to tune a scale.
Could you give us some advice on how to tune a scale.
I don't shoot competition. People tell you not to do it but I put a small amount of oil on the bearing to reduce friction. It cannot hurt anything as long as you keep it clean. I had a chemistry lab course many years ago and I was taught to judge the zero with the beam slowly moving a small amount above and below the zero mark. Have not bothered to check sensitivity for one grain of powder. If the beam is moving a small increment above and below the zero it will normally stop on zero with one swing. Bearing friction can cause the beam to stop to early. Don't know anything about custom improved scales except what's on this website.
Funny about that. I was trying to find an article from a good few years back where the author claimed that he got the best accuracy from shooters' scales when the magnets were removed by using oscillation either side of the zero.
BoydAllen
Gold $$ Contributor
Reloading scale bearings run best when they are dry. For many, tuning a scale is best left to a professional. Once you have the bearings and their holders clean and dry, one of the main issues is the sharpness of the knife edges. Another one is whether the frame of the scale is level when the scale is zeroed. You want the vertical CL of the knife edge angle to evenly divide the angle of the bearing. Correcting this involves adjusting the tuning weights in the pan holder. Beyond this there are other issues that some careful examination and thought should reveal to you. Scott Parker is the man for professional work on balance reloading scales. You can do a search on this site to come up with his contact information. Earlier, he posted in this thread. You can use that as a starting place to PM him.
Boyd is correct, there is alot to tuning a scale. Scott tuned my 10-10 and it is smooth and repeatable.
Took the scale to the shop this morning and under magnification I could see some very fine corrosion around the sharp edges of the pivots on the axle. I cleaned that up and polished them a bit and the scale seems to be functioning much better (returning to the zero point). I'll give it a shot at the reloading bench again tonight and see if the problem has really been resolved. If not, I guess I'll send it to Scott and let him figure it out.
Brians356
Gold $$ Contributor
Boyd, that must obviously be true WRT OEM magnets, which from my observation are always of a "horseshoe" configuration. My 5-0-5's magnets are 'C' shaped horseshoes, and my M5's are large cylinders with a 'V' notch and are also a type of horseshoe.
But in experimenting recently w/ replacement neodymium magnets in my M5, a non-horseshoe configuration (one N42 cylinder magnet on each side of the blade, with a single 'N' pole opposite a single 'S' pole, i.e. in coaxial alignment) had the magnets "capturing" the copper blade, so that the beam pointer followed the zero mark up and down through the full range of scale level adjustment!
So it's not strictly true of every possible configuration that "the magnets exert no force on the scale beam", but I believe that must obviously be true of proper OEM configurations, otherwise the scale would be rendered worse than useless.
In order to use cylindrical neodymium magnets to dampen but not interfere with the beam zero, I had to use 2 magnets on each side, slaved together into horseshoes with a steel tie bar. (Described in detail here: http://forum.accurateshooter.com/threads/on-beam-scales-part-two.3906350/page-8#post-36833260)
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Brians356
Gold $$ Contributor
You can guess and play with your scale, or, send it to the knowledgeable, experienced professional (Scott) and live happily ever after, knowing it is repeatable and dead on
Translation: Don't worry your pretty little head studying your scale and learning for yourself what makes it tick.
That's the spirit!
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That's what Hawking thought about Einstein. He too thought figuring it out himself was going to be the best way, until he finally realized he was wrong, and admitted Einstein was correct, all alongTranslation: Don't worry your pretty little head studying your scale and learning for yourself what makes it tick.
That's the spirit!
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Brians356
Gold $$ Contributor
That's what Hawking thought about Einstein. He too thought figuring it out himself was going to be the best way, until he finally realized he was wrong, and admitted Einstein was correct, all along
Cute. Your analogy would be apropos if only I happened to have disagreed publicly with Parker about how a simple balance beam scale functions.
You know, I think you obviously made the right choice in sending your scale to Scott.
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You bet I did
He has no equal, when tuning a scale Function is one thing. Repeatable accuracy is quite different
Personally, I prefer to spend my time hunting, or, enjoying a nice vacation, rather than worry about a paltry amount of money to have a pro perform his/her thing, simply to say I figured it out and can do it myself.
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