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Old December 2, 2012, 08:29 PM   #1
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Problem with RCBS 505 Scale

So I've been using a RCBS 505 scale for the last few years. I went down to reload tonight and am having a problem with it. I had this problem in the past once before and I tried it out again the next day and it worked fine.

The problem I'm having is when I try to zero the scale it seems like it's way off. So I adjust the height of the scale to zero it and once I get it zeroed I take the pan off and put it back on, and the scale has a different reading. I can then take the pan off and put it back several times and the scale has the same reading, but the marks will no longer be zeroed the mark on the beam will usually be higher reading like something is in the scale. I will then zero it again to these marks. Then once I remove the pan and put it back on, the beam will be quite a bit lower. It's just a back and forth cycle and I can never get it zeroed so that it will read the same thing after removing the pan and reinstalling it.

Anyone had this issue? Any tips to get it fixed? Having had this issue, it always makes me scared it's going to act up while in the middle of loading and throw my loads off, but so far I've been pretty lucky with that.
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Old December 2, 2012, 09:03 PM   #2
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Fusion, first make sure all the conditions are right, solid level surface, eye level, no draft and clean the hinge point. Do you have weight checks? I zero mine then check the calibration with several weights varying from .2 to 20gr. And then back to zero. I also always tap the beam and let it bounce to make sure it "settles" correctly. It seems sometimes with small weights it "hangs" usually a little low.
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Old December 2, 2012, 09:57 PM   #3
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Fusion, I have the same exact problem with my 505. Very fustrating!
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Old December 2, 2012, 10:29 PM   #4
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Dust in the "v" grooves.
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Old December 2, 2012, 11:30 PM   #5
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+1 ^ ! The 505 is a great scale. Dust or bigger gunk is causing your problems.
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Old December 3, 2012, 08:07 AM   #6
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That is exactly the way my beam scale behaves if there is dust in the v-groove where the knife edge rests.

So, I ALWAYS clean the v-groove AND the knife edge with a Q-tip before I zero and use the check weights.

That has always resulted in the scale holdng zero and giving proper check weight readings for me.

If that doesn't work for you, then I would suspect that the knife edge has been damaged.

When you clean it, be careful that you don't damage the knife edge. You are just trying to remove dust, not scrub it or polish it.

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Old December 3, 2012, 08:36 AM   #7
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I would also suggest to simply/gently "tap the table" next to the scale as you would when people "drum" with their fingers. You would be amazed how this simple action settles things out to a true reading -- both quickly & precisely every time.
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Old December 3, 2012, 07:45 PM   #8
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Thats guys. do your "White plastic V grooves" move around freely? Meaning are yours fixed or are they able to move. Mine can move around in the holder. I have a 505

Last edited by jhabers; December 3, 2012 at 08:00 PM.
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Old December 3, 2012, 11:29 PM   #9
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I have the Dillon equivalent and had noticed the same problem. One other thing to look at is the poise or what ever its correct name is (the thingy that you move to change weight). When set to 0 for the 1 grain portion of the scale, it would sit at different angles. It was in the 0 notch but it hung down at different angles. Once I started making sure that was the same every time, most of those problems went away. So clean and make sure it always sets at the same angle.

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Old December 4, 2012, 08:11 AM   #10
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The "plastic grooves" on my scale also move SLIGHTLY. That has never been a problem for me. I suspect (but don't really know) that it was designed that way so that the "grooves" can align with the knife edges on either side of the beam. Any misalignment might cause unreliable measurements.

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Old December 4, 2012, 08:21 AM   #11
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The "plastic grooves" are not "plastic" but are Agate, a type of quartz.

The agate pieces are ment to move so the knife edges can aline properly.

The agate give the knife edges a place to rest that will not change over time, like a metal will (corrision,rust).
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Old December 5, 2012, 10:22 PM   #12
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Every so often you may need to remove the notched agate blocks and clean the housings they set in as well. They are supposed to float unimpeded in their cradles to function properly. Good old rubbing alcohol works fine to clean these as well as the stones and the knives on the beams.
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Old December 5, 2012, 11:41 PM   #13
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The very slighest draft will throw things off too. It's winter, is there an air duct anywhere nearby? Keep a cloth cover over it when not in use so as to keep it clean.
The blood runs free, the rain turns red, give me the wine, you keep the bread.
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Old December 6, 2012, 08:53 PM   #14
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OK, I "fixed" my probelm. I know this is not the right way to do it and I'm sure someone will say that I messed something up but its rock solid consistent now with reading weights.

Whats I did was I noticed the "agate grooves" would pivot on the frame a bit, so I took a piece of paper and folded it once and then cut a tiny square out of it. I put the piece on one side of the "agate groove" piece so that it would fit snug in the frame so it would not move at all.

I know that this is not the way that the scale is designed to work but the scale works rock solid now

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