scales and magnetic dampening

[Brians356]

You bet I did He has no equal, when tuning a scale Function is one thing. Repeatable accuracy is quite different

I rest my case.

"A man's got to know his limitations."

 

[clowdis]

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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While I have no doubt of Scott's ability to make a scale work correctly and with repeatability, I, too, would like to know something about my scale and what makes it work correctly. I equate it to somebody bringing their trigger to me at a match to adjust. I don't mind doing it but I always wonder why you would take such a simple thing to someone else to do when you really ought to know how to do it yourself. If the scale still doesn't repeat then I'll ship it to Scott.

 

[1066]

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.
(Described in detail here: http://forum.accurateshooter.com/threads/on-beam-scales-part-two.3906350/page-8#post-36833260)
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As Boyd say, the magnets will have no effect on the copper blade once it's stationary.

Where you say, by moving the magnets you have managed to get the copper blade to follow them through the range - What I believe is happening is that, on the M5 (and10/10) scale, the small stud where the auxiliary weight hangs is ferrous, this is what is being attracted to you magnets. I you never use the auxiliary weight, you could remove the stud and replace it with a similar weight brass nut and bolt.

This problem doesn't show up on the old RCBS 5-10 because, although it has exactly the same beam as the 10/10 it doesn't have the steel stud for the weight.

 

[Brians356]

As Boyd say, the magnets will have no effect on the copper blade once it's stationary.

Where you say, by moving the magnets you have managed to get the copper blade to follow them through the range - What I believe is happening is that, on the M5 (and10/10) scale, the small stud where the auxiliary weight hangs is ferrous, this is what is being attracted to you magnets. I you never use the auxiliary weight, you could remove the stud and replace it with a similar weight brass nut and bolt.

This problem doesn't show up on the old RCBS 5-10 because, although it has exactly the same beam as the 10/10 it doesn't have the steel stud for the weight.

Um, the auxiliary weight doesn't hang from anything, it stands free in a cavity cast into the body. Furthermore, the auxiliary weight itself is non-ferrous. Besides, even if the weight or some hanger were ferrous, that could not explain the beam following the motion of the scale body (via the leveling screw). Only if the auxiliary weight was itself actually a very powerful magnet could that happen. To repeat, when I change the arrangement of the magnets (and nothing else) the "capture" effect disappeared completely. FWIW with the current magnet configuration, the scale is wonderfully repeatable, highly sensitive, and the settling of the beam happens roughly twice as fast as with the OEM magnets.
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[1066]

Um, the auxiliary weight doesn't hang from anything, it stands free in a cavity cast into the body. Furthermore, the auxiliary weight itself is non-ferrous. Besides, even if the weight or some hanger were ferrous, that could not explain the beam following the motion of the scale body (via the leveling screw). Only if the auxiliary weight was itself actually a very powerful magnet could that happen. To repeat, when I change the arrangement of the magnets (and nothing else) the "capture" effect disappeared completely. FWIW with the current magnet configuration, the scale is wonderfully repeatable, highly sensitive, and the settling of the beam happens roughly twice as fast as with the OEM magnets.
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Ahh! I think you might be missing a trick there Brian. The auxiliary weight is designed to hang on the beam, on the little ferrous stud that sticks out near the pointer. The purpose of the weight is that it increases the range of the scale from 500-1000 gns. It also, of course, acts as a check weight because the actual weight is stamped on it.
The use of a steel stud on the pointer end of the beam is a very poor design feature, especially as it's only an inch away from the damping magnets.

 

[Brians356]

Ahh! I think you might be missing a trick there Brian. The auxiliary weight is designed to hang on the beam, on the little ferrous stud that sticks out near the pointer. The purpose of the weight is that it increases the range of the scale from 500-1000 gns. It also, of course, acts as a check weight because the actual weight is stamped on it.
The use of a steel stud on the pointer end of the beam is a very poor design feature, especially as it's only an inch away from the damping magnets.

Yes, we're like two ships passing in the night. I thought you meant the weight was hanging while not in use. I will check out the hanger stud on the beam and any interaction with the magnets I was using at that time. (The scale no longer has that problem, with much smaller, less powerful magnets, arranged as horseshoes rather than simple axially-magnetized.)
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