Ohaus 505 Scale Problems


The Grand Baboon
January 26, 2012, 11:05 PM
I've been using a 30 year old Ohaus 505 to weigh all my powder but I'm having issues with it. I think the "magnetic dampening" is a bit too powerful. Sometimes if I put a little bit too much powder the arm will swing up and the magnets will prevent it from coming back down, even if I take the few grains of powder out with a spoon or something.

I'm thinking about taking out one or two of the magnets, is this a viable solution?

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January 26, 2012, 11:14 PM
I'd advise contacting the company. I got a used 5-0-5 - branded RCBS - as part of my used set-up purchases. It was squirrelly, just couldn't get it to settle consistently. I contacted RCBS, they said send it in. Ten days later - a brand new 5-0-5 scale arrives in the mail.

I'm not sure about your scale, but I'd contact the manufacturer and hope for the same treatment (I believe Ohaus makes the scales for RCBS?).

I would expect the very wise and vastly more experienced regulars here to agree. The scale may be your most important piece of reloading gear. No reason to put up with the hassle of balky performance, and reckless to trust it with your most important reloading measurements.

January 27, 2012, 01:01 AM
Here another cause of erratic or slow behaviour:

I've noticed the RCBC 505's knives must be kept free from dirt, dust, fuzz or fluff of any kind, otherwise the beam action is impeded.

I store mine under a clear platic cover. The knives and agate beds get cleaned with Qtip & rubbing alcohol 1x/year.

January 27, 2012, 06:13 AM
I've had the same problem with mine, usually it's the knives that need cleaning.

January 27, 2012, 06:54 AM
X3 on cleaning the knives and pivots, it fixes my Lyman scale if it starts to act up.

The Grand Baboon
January 27, 2012, 08:58 AM
Ok. I'll clean it up and give it a shot.

January 27, 2012, 10:04 AM
Yeah, the knife edges and bearing blocks need to be kept spotless.
Careful wipe down with lintless swabs and alcohol and a puff of canned air like used for photo gear will help get the lint and dust off.
Also helps to keep the scale covered when not being used, even though the cover for my old Lyman/Ohaus M-5 is always nearby, I'll often forget to put it on.

January 27, 2012, 11:25 AM
I make it a habbit to "drum" the table that the scale sits on with my fingers
to settle out the pointer -- oil damped or magnetic damped alike.

Works like a charm.... :)

January 27, 2012, 12:04 PM
Perhaps a static charge has built/builds up.

January 27, 2012, 12:06 PM
It has nothing to do with the magnets.
Don't mess with them.

Clean the bearings & knife edge with a cotton Q-Tip and rubbing alcohol.

Then get a small carpenters bubble level, and make sure the bench & scale is level sideways before you zero it.

Then, make sure you center the beam in the blocks so neither end of the knife edge is rubbing on the base.

Then make sure you don't have a furnace vent blowing air on it.

Then make sure you don't have a light ballest or electric motor causing a magnetic field close to the scale.

Then cover the scale when you are not using it and it won't collect dust in the knife bearings.


January 27, 2012, 12:06 PM
Mine will do that when it gets dirty. Like others said the bearing and knife surfaces must be spotless.

January 27, 2012, 12:23 PM
i folded a sheet of 8.5"x11" paper longways and keep it over my 505 like a tent when not in use. they also sell scale covers, but the paper works fine for me.

January 27, 2012, 12:27 PM
I deffinitely wouldn't alter it's functions. Every now and then mine, a 5-10, will act up. It's always a case of needing dusting. I use a a plain dry soft tooth brush to brush the magnets off and the blades that the beam pivots on, and as well the beam it's self and the slide weights. Other than that, there is no real areas of function that can go bad.
Also make sure you don't have anything within several feet of the scale that can create a magnetic or static field such as, anything that has a motor in it like a tumbler for instance, certain types of lighting can also cause problems, so I've been told.
But what ever you do, don't mess with the inherent functions of the scale. Not only doing so would defeat it's well designed function, but it could void the warrenty, which RCBS is so well known for.

The Grand Baboon
January 27, 2012, 12:32 PM
Ok, I'm showing my ignorance here, but what exactly is the "knife" of a scale?

Edit: Nevermind, I think I found it.

Should I be wary of shooting any ammunition I loaded before cleaning it?

January 27, 2012, 12:35 PM
the fulcrum for the beam. lift the beam off the base and you'll see it.

January 27, 2012, 12:36 PM
The little sharp edged bars on the beam that drop onto the floating V-blocks mounted to the base itself.
Old ones used to be agate, don't know what they are now.

January 27, 2012, 01:25 PM
I'm glad to see this as I have a the same situation. My scale is an Ohaus 505(?) I got off of ebay some time ago. It is Ohaus branded. All the metal is bright orange and has a tan plastic cover so that you can "pack it up" and store it. I don't know if the RCBS scales pack up or not. It seems sluggish at times, so I will probably try RCs tips above.

January 27, 2012, 02:03 PM
quote: "Should I be wary of shooting any ammunition I loaded before cleaning it?"

That there, zreed042, is a very astute question.

Since your scale's action was likely impeded by the resistance to movement of fluff/dust, you can not be entirely sure that the loads you developped will weight out the same once the scale is clean and pivots freely.

This problem would likely have developped gradually over time: dust falls everyday on an uncovered scale and so resistance to movement would have grown imperceptibly every day. This resistance could just as easily be to upward or downward movement.
Therefore, with a clean scale, your loads might just as easily be slightly heavier or slightly lighter. This outcome would be most pronounced for the last loads your developped as that is when the scale was 'dirtiest'.

If your loads are middle of the road, probably not a problem.
If they're at the low or top end...there might be a problem.

January 27, 2012, 02:19 PM
I made a little wood box for mine to set on so it is up where I can read it with bifocals!

The box doubles as a scale cover when it is not being used as a stand.


January 27, 2012, 03:06 PM
Who here makes sure that they don't especially store and or perhaps use their precious upon the loading bench proper?
Unless it's a NASA grade granite or steel test bed, day after day, stroke after stroke, that's gotta take its toll.

The Grand Baboon
January 27, 2012, 03:14 PM
If your loads are middle of the road, probably not a problem.
If they're at the low or top end...there might be a problem.

Well, I went ahead and shot them (a little over 3/4" at 100 yards:D). It was a few rounds of 308. with 42.5 gr of RL-15.

The scale is acting much better after cleaning it. Thanks guys, I appreciate your help.

And RC, that's a wonderful idea. I'm going to build myself a box too. I hate having to crane my neck to see the scale perfectly.

January 27, 2012, 03:18 PM
"...make sure you center the beam in the blocks so neither end of the knife edge is rubbing on the base."

80% probability that's your trouble point, 20% it's dust in the V bearings/knives. For sure, it's not the magnet.

January 28, 2012, 12:56 AM
^ ranger335v you've reminded me that I've been thinking of finely stoning the very ends of my 505's knives (the triangular cross-section, not the fulcrum's bearing edge) in an effort to minimize the times that they hang up on the inside of the keeper plates (the metal endpieces held in place by a small phillips screw).

Whenever the beam 'acts up', I give it a gentle nudge next to the knives. This usually re-centers the knives away from the endpieces. Maybe there are some burrs on the knife ends which could be stoned out.

Anybody else try this?

January 28, 2012, 01:00 AM
zreed042 those 308s sound like a great load with tolerance for being out by .1gr.
They probably also perform equally well in all weather conditions.

January 28, 2012, 08:39 AM
What Certaindeaf said.
After not reloading and shooting for several years I started again about a year ago. Could not get my scales consistent. Finally realized that it was setting on my reloading table and being jiggled with every pull of the press handle. They need to sit on something that is not even attached to the bench.

January 28, 2012, 08:55 AM
Well, a scale certainly shouldn't be used someplace it's constantly vibrated.
But, then a bench should be solid enough it's not going to move with a simple stroke of a press!

January 28, 2012, 11:42 AM
My bench is pretty dang solid but I don't keep a beam scale on it. I've also been known to load with a doublejack sledge for sentimental reasons too.. gotta love those old LEE loaders.

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