Erratic Beam Scale

[D.B. Cooper]

In a different discussion, jmorris suggested I check the consistency of my Redding No.2 beam scale. Sure enough, it's not right. Using a set of RCBS check weights and starting with a "zeroed" scale, the scale indicated 1.0 grain under at 0.5, 1.0, 5.0 and 10 grains. It was dead on zero at 15 grains. It was just barely under at 20 grains, and it was 0.5 grains over at 40 grains. At 50 grains, it was just under zero.

Before I call Redding and go down the road that leads to me mailing this thing back to them, is there anything I can do to correct this issue? Is it possible (even probable) that I am doing something to induce this error?

PS: The bench on which I use the scale is pretty level, but I haven't actually checked it. I have a 4 ft builder's level and various torpedo levels with which to verify the level of the bench, and thus the scale, if folks here think that is critical. I don't think it is that big of a deal-the table is flat and mostly level and the beam zeroes; as long as I don't relocate it after zeroing it, I think it should be okay. I don't think it will be possible to maintain a perfectly level bench anyway.

 

[edwardware]

. . . the scale indicated 1.0 grain under at 0.5, . . .

It reads negative 0.5 grains with the 0.5 grain weight, set to 0.5 grain?

The bench on which I use the scale is pretty level. . .

The bench being level is irrelevant, so long as it holds still. Zero the scale with the screw, loose the level.

Trying to sort through your text, it's possible your knife edges are damaged. I would suggest:
1)Flip it over, remove the screw holding the magnets. Don't worry, unless you strip the screw hole this is reversible.

2) Set it back up, zero it, and observe the oscillation. If it's not smoothly oscillating, gradually slowing down, something's wrong. If it's catching, I think you have damaged edges.

3) Reinstall the damping magnets and screw.

 

[D.B. Cooper]

It reads negative 0.5 grains with the 0.5 grain weight, set to 0.5 grain?

That is correct.

 

[edwardware]

That is correct.

I have to wonder. . . did you zero it first?

 

[higgite]

..........Using a set of RCBS check weights and starting with a "zeroed" scale, the scale indicated 1.0 grain under at 0.5, 1.0, 5.0 and 10 grains......

Something isn't adding up here. (No pun intended). OP said in post #1 that the scale was zeroed. How can a balance scale that has been zeroed read less than zero when you add weight?

 

[edwardware]

How can a balance scale that has been zeroed read less than zero when you add weight?

Only way I can image is if the tenth poise is twice as heavy as it should be. . . I think not.

 

[Riccochet]

Are your check weights accurate? My Lyman set sure as hell are not. My 10gr is actually 9.36gr, both 20gr are 20.2, the 5 is 5.1 and there are some slight variances in the 1 and .5 weights. I have a pile of digital scales and two beam scales that measure them all the same.

I emailed Lyman and have yet to get a response.

 

[cfullgraf]

The knife edges and pockets may be dusty causing erratic behavior.

Some clarity is needed in description of the problem. Maybe the decimal point is in the wrong place.

 

[Slamfire]

The knife edges and pockets may be dusty causing erratic behavior.

Some clarity is needed in description of the problem. Maybe the decimal point is in the wrong place.

I was having repeatability issues with my Redding #2 , took the beam off, cleaned the bearings and beam knife edges with "Goof Off" and a Q-TIp. Everything went back to normal.

 

[Whiterook808]

Are your check weights accurate? My Lyman set sure as hell are not. My 10gr is actually 9.36gr, both 20gr are 20.2, the 5 is 5.1 and there are some slight variances in the 1 and .5 weights. I have a pile of digital scales and two beam scales that measure them all the same.

I emailed Lyman and have yet to get a response.

I have the same problem with my Lyman check weights. Two digital and one RCBS 10-10 agree that at least one of the 10 grain weights is off, weighs 10.1 grains.

 

[CarJunkieLS1]

I had a very similar issue with my RCBS beam scale. It was spot on from 0-29.9gr and 40.1-max weight. It was off and even inconsistently of between 30 and 40 grains. RCBS got it back and replaced it with another and it's dead on everytime.

Beats me as to the reason why it was the way it was.

 

[coondogger]

DB, do you have any large plastic or styrofoam objects right next to your scale? They can produce a surface static electricity that will cause a deflection in a balance beam scale. These type of scales are vulnerable to this deflection because they are damped by a magnet.

 

[D.B. Cooper]

Are your check weights accurate?

If they are or are not, I have no way to verify it. Every scale on the market measures to 1/10 of a grain; there is no way to b e precise with any of this. If I weigh the check weights on another scale, who is to say that scale is correct? All I can say is that, according to Redding, every scale is checked with ASTM (or some other organization) approved weights before being shipped.

 

[D.B. Cooper]

DB, do you have any large plastic or styrofoam objects right next to your scale? They can produce a surface static electricity that will cause a deflection in a balance beam scale. These type of scales are vulnerable to this deflection because they are damped by a magnet.

I never thought of this. I'll recheck everything on an empty bench as soon as I have time and can access my bench.

 

[Mal H]

As higgite implied, you need to refine the way you are describing the problem. The scale can't read 1.0 grain low with only the 0.5 grain check weight in the pan.

A suggestion - Starting with a zeroed beam, list the results of the individual check weights like this:
0.5 grain weight reads xx grains
1.0 grain weight reads xx grains
etc.

And check each one several times to see if there is a variance for each check weight. Be sure the scale returns to zero after each weighing.

 

[D.B. Cooper]

As higgite implied, you need to refine the way you are describing the problem. The scale can't read 1.0 grain low with only the 0.5 grain check weight in the pan.

A suggestion - Starting with a zeroed beam, list the results of the individual check weights like this:
0.5 grain weight reads xx grains
1.0 grain weight reads xx grains
etc.

And check each one several times to see if there is a variance for each check weight. Be sure the scale returns to zero after each weighing.

Using a set of RCBS check weights and starting with a "zeroed" scale, the scale indicated the following:

0.5 grain weight reads -1.0 grain
1.0 grain weight reads -1.0 grain
5.0 grain weight reads -1.0 grain
10.0 grain weight reads -1.0 grain
15.0 grain weight reads 0 grains
20.0 grain weight reads somewhere between negative 0.5 and 0 grains
40 grain weight reads +0.5 grains
50.0 grain weight reads somewhere between negative 0.5 and 0 grains

Hope that makes it clearer.

 

[edwardware]

Hope that makes it clearer.

A Redding #2 can't read -1.0 grain on the beam pointer; the pointer range is only -0.6 grain to +0.6 grain. Any indication larger than that is via poise weight position.

I think a picture of the scale:
1) zeroed, and
2) with the 0.5 check weight
will clarify things. I have to think you're reading it incorrectly.

 

[JimKirk]

DB .... With your scale set on zero ....not moving any poises .... add the 0.5 grain test weight .... does the left side of the beam move up or down?

 

[Blue68f100]

Just a reminder that you should not be touching your calibration weights with your fingers. The oil and acid from your skin can effect the weight.

ALWAYS USE TWEEZERS WHEN HANDLING CALIBRATION WEIGHTS.

 

[Riccochet]

DB .... With your scale set on zero ....not moving any poises .... add the 0.5 grain test weight .... does the left side of the beam move up or down?

If it moves down Lyman just may have discovered anti-matter.

 

[higgite]

If it moves down Lyman just may have discovered anti-matter.

Or anti-gravity.

DB, just for clarity, can you post a pic of the scale while it is weighing one of the check weights that gives a negative reading and tell us what you interpret that reading to be?

 

[buck460XVR]

Are you mistaking the tenth of a grain increments on the left side as grain increments?

 

[JimKirk]

If it moves down Lyman just may have discovered anti-matter.

That was the reason I asked that sort of question .... If it moved down ...

THEN we should all be worried!

He is a little close to Russia .... they probably causing it ... !

 

[Slamfire]

Is the beam bent so that the "copper colored fin" (CCF) is parallel, or at least clearing the damping slot of the scale? That could cause weird readings by binding. That would not explain negative readings with a 50 grain check weight. A simple question, does the beam move freely with just the slightest touch, on the "0" setting?

How about a picture of from the top and sides, with your 50 grain check weight, maybe we can see if something is bent.

 

[Mal H]

Hope that makes it clearer.

Nope, not at all. As the others have said in different ways, you are saying the 0.5 grain weight makes the beam pointer go down when, in this universe, it should always go up, even if it goes too far or not far enough. And you are also saying that for the weights from 0.5 to 10.0 grains, the pointer is stuck at -1 grain.

Something is being lost in translation.

If I had made my list like this in my first post, would it have been clearer what we are looking for (sub "weighs" for "reads")?
0.5 grain weight weighs xx grains
1.0 grain weight weighs xx grains
etc.