On beam scales part two
- Thread starter sparker
- Start date
6MMsteve
Gold $$ Contributor
I found a 1 inch x 1/16 thickness x 1/2inch w 30 set of mags on ebay gonna try those, I have 2. 3/4x1/16x1/4 in now and it works pretty slick they are 40's using a 10gram test wt that is calibrated to check scale 154.5 or something like that I forgot, but I zero my scale every time I weigh charges hopefully I will not blow myself knock on my head I mean wood
Brians356
Silver $$ Contributor
On recommendation in this thread, I ordered two N42 magnets. I tried two 1/2 x 1/2 x 1/4 in my M5, and set them as far back from the paddle gap as I could, using balsa spacers (the magnets are actually about 3/4" apart.) They failed miserably. The pointer takes literally a minute or more to settle, and all the while is in a rapid oscillation confined to about 1-1/2 clicks either side of zero. It's almost like a perpetual motion machine. Obviously the magnets are actually inducing the oscillation! This with the magnets oriented NS- [] -NS.
I tried using only 1 magnet (outboard position) in both pole orientations, and it was no improvement.
Seems like they are way too powerful, but there could be other effects in play.
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3/4"??? The ONE 40 in my D5 about an 1/8" from the blade. I'm not the best wideo
maker but hopefully you can see how only one 40 works.http://tinypic.com/usermedia.php?uo=uW4M4OjFxsZcKPWXxCujSYh4l5k2TGxc
Bill
Brians356
Silver $$ Contributor
3/4"??? The ONE 40 in my D5 about an 1/8" from the blade. I'm not the best wideo
http://tinypic.com/usermedia.php?uo=uW4M4OjFxsZcKPWXxCujSYh4l5k2TGxc
Bill
I don't know what a "40" is. Mine are N42s, and 0.0625 cubic inch in volume.
The 3/4" is the distance between the magnets, they're about 3/8" from the blade.
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Brians356
Silver $$ Contributor
Ok, I see the basic problem. The OEM magnets in both my RCBS (Ohaus) 5-0-5 and my Lyman (Ohaus) M5 are a type of shallow horseshoe magnet. They all have notches in them, and there is a S pole on one side of that notch, and a N pole on the other side. The magnets are positioned with their notches facing each other, and their magnetic moments are parallel to each other. Magnet A's S pole is directly opposite magnet B's N Pole, and Magnet A's N pole opposite B's S pole. Hence the pair form a circuit loop, with the force lines and the magnets themselves tracing a squared circle - not unlike an electrical circuit. The copper blade is exposed to two main force lines "flowing" in both directions near the ends of the magnets, with a sort of neutral area between the middles of the magnets where the flow lines are mostly parallel to the copper blade:
The effect of this arrangement is to confine the blade inside the wide neutral area, but within that area to not exert much influence on the blade.
When I tried my N42 block magnets, the blocks' magnetic moments (vectors) were aligned coaxially. The magnets are positioned end-to-end magnetically, across from each other, with a single N pole directly across from the other magnet's S pole, with the blade between. The other S and N poles are on the back sides of the magnets, facing away from the copper blade. The force lines are flowing in a single direction, and largely perpendicular the the blade. Also rather than a neutral area where the blade resides, the flow lines are closest together (strongest) near the center of the blade:
In this arrangement, with powerful neodymium magnets, they try to center the blade in the strongest force area, directly between the two magnets.
As proof of that, consider what happened when I mounted a single N42 magnet with one pole pointing at the copper blade. The magnet attracted the blade, centering the blade on the magnet's magnetic moment vector. I could move the scale's leveling leg adjustment up and down through the full range of adjustment (more than an inch) and the beam pointer stayed centered on the magnet (and pointing to zero on the scale's indicator) from one end of the adjustment to the other!
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Brians356
Silver $$ Contributor
I reported earlier that using N42 magnets in my M5 with their magnetization vectors aligned coaxially attracted and captured the copper beam blade, making zeroing the scale impossible - the beam pointer followed zero wherever it went! I said that the OEM magnets in both my M5 and my 5-0-5 were positioned with the magnetic vectors aligned in parallel, which creates a weak eddy zone in the region between the magnets, with strong attraction in the "overswing" areas beyond the middle area.
I then obtained a couple of N42 bar magnets with dimensions 1/8" x 1/8" x 1/2", magnetized longitudinally (poles at the skinny ends of the bar.) These were positioned in the M5 parallel to each other, as shown in this diagram:
This arrangement did not exhibit any tendency to capture the blade, but rather had the same type of damping effect as the OEM magnets have. However, the damping effect is rather weak - the OEM magnets allow the beam to oscillate with the pointer crossing zero a total of 9 times (counting both directions), from a fully deflected beam position (against the bottom stop) before settling on zero. These new N42 magnets (positioned farther from the blade because of the protrusion in the housing) allow the pointer to cross zero 18 times before settling. But settle it does, and repeatably maintains a zero adjustment.
I will try the next larger size N42 bar magnets, 1/4" x 1/4" x 1/2", which will have 4x the mass and almost 5x the pull force, so I may have to move them even farther from the damper blade if they are too strong.
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I then obtained a couple of N42 bar magnets with dimensions 1/8" x 1/8" x 1/2", magnetized longitudinally (poles at the skinny ends of the bar.) These were positioned in the M5 parallel to each other, as shown in this diagram:
This arrangement did not exhibit any tendency to capture the blade, but rather had the same type of damping effect as the OEM magnets have. However, the damping effect is rather weak - the OEM magnets allow the beam to oscillate with the pointer crossing zero a total of 9 times (counting both directions), from a fully deflected beam position (against the bottom stop) before settling on zero. These new N42 magnets (positioned farther from the blade because of the protrusion in the housing) allow the pointer to cross zero 18 times before settling. But settle it does, and repeatably maintains a zero adjustment.
I will try the next larger size N42 bar magnets, 1/4" x 1/4" x 1/2", which will have 4x the mass and almost 5x the pull force, so I may have to move them even farther from the damper blade if they are too strong.
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I just got on the "M5 Party" too. I have won an ebay auction for a nice one tonight. Now the waiting begins...
Danny
Brians356
Silver $$ Contributor
From Page 1:
Q: What scale do you recommend?
A: An M5 if you have the scratch, a Redding or a D5 or older 502 if you are on a budget, all need tuning and calibrating.
Q: What scale do you recommend?
A: An M5 if you have the scratch, a Redding or a D5 or older 502 if you are on a budget, all need tuning and calibrating.
OK, Slightly confused here,
Since I am not familiar with all the scale types/brands etc,
M5 = Lyman
Redding = What model???
There is at least 2/3 different types/models, I have found.
D-5 = Lyman/Ohaus????
502 = RCBS
Tia,
Don
A: An M5 if you have the scratch, a Redding or a D5 or older 502 if you are on a budget, all need tuning and calibrating.
OK, Slightly confused here,
Since I am not familiar with all the scale types/brands etc,
M5 = Lyman
Redding = What model???
There is at least 2/3 different types/models, I have found.
D-5 = Lyman/Ohaus????
502 = RCBS
Tia,
Don
Does the metric rcbs 5-10 gram version hold any resale like the grain version? I missed the metric part of the description when I bought it. Until late then I was under the impression that all 5-10's were grains.
I found a 5-10 in grains in better shape cheaper afterwords of course. I may consider sending that one in for a tune after my wallet recovers from some recent purchases
I found a 5-10 in grains in better shape cheaper afterwords of course. I may consider sending that one in for a tune after my wallet recovers from some recent purchases
Glad to hear you're happy with your scale. I sent Scott my m5 a couple of weeks ago to have tuned and accurized. Spoke to him yesterday - mine is on schedule. Looking forward to having an accurate and repeatable scale for my future reloading.
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