Beam Scale Trouble

I'm a little new to reloading and I want to do everything right but I'm having trouble with my powder scales. I have an older RCBS (not sure of model), a Lee safety scale and a cheap Hornady digital and I like the RCBS best for ease of use but both my beam scales have the same problem.
The problem is that when I zero them they will settle out for a second then start jumping around again. They will also do the same thing when I try to weigh a powder charge. I've tried them in different rooms thinking I was getting some kind of weird electrical interference or air flow from the ceiling fan but got the same results. I've also cleaned the scales and inspected them really well and can't find anything wrong visually.
Is there anything I can do to fix this problem or am I doing something wrong?

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Yes there is. The pivot on the beam is basically a triangle with the angle that sits on the base needing to be a knife edge. I use a magnifier and an DMT Red Diamond Hone. Carefully dust both sides of the pivot on each side of the beam until you have a sharp surface. You must get the hone at the same plane of the pivot. any flat or dull spot may have an impact on consistency.

Also, clean the base were the beam pivot sits. I add some mineral oil and that works for me. Your mileage may vary.

Always remove the beam from the base after using and protect those edges. There are wicked vibrations coming from underfoot that may accelerate the wear on the pivot.

Robinhood, do you have a link to the ADT red diamond hone you use?

Do yourself a favor and throw away that cheap POS digital scale. Will get you killed. I had the RCBS digital scale that came with my reloading kit. Thought it was good until I got a gempro 250 and saw how much I was off. I did get the Lee beem scale but thats off too. Spend the money and buy a good beam or digital scale. Which ever your more comfortable with.

I would be very careful when filing or otherwise altering the knives on a beam scale. That being said they do need to be very clean. I use either alcohol or electronic contact cleaner and a lens cloth .Also check to make sure the ways the knives ride in are also clean and the ends of the knives are not hitting the end caps. If the knives and the ways are clean and the knives are not damaged and gravity is present then the beam scale should work.

My recommendation is either a good beam modified with a camera and a extended pointer or as bearcatrp suggested a Gempro 250 electronic or other good electronic scale. A friend of mine uses a Sartorius lab scale which cost over $1000. On a bet he brought it over and we checked my ancient RCBS against it and the beam was just as accurate as his high dollar scale

if you go with the beam here is a page that has some videos on how to modify various beam scales to make them more user freindly

https://www.youtube.com/user/thetargetmaster/videos

Before I went to filing I would do a thorough cleaning of the contact points on the beam scale. They are usually very fool proof (it's all I use and have for decades).

It's possible something is loose in the 1/10th adjuster. Some have a weight that runs up and down a threaded rod. Make sure that rod is secured.

Clean the "V" and arms on the beam that set in it.

Make sure it is absolutely level and on a solid surface. It didn't loose a foot or pad underneath?

Quote:

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Originally Posted by Stumpkiller

Before I went to filing I would do a thorough cleaning of the contact points on the beam scale. They are usually very fool proof (it's all I use and have for decades).

It's possible something is loose in the 1/10th adjuster. Some have a weight that runs up and down a threaded rod. Make sure that rod is secured.

Clean the "V" and arms on the beam that set in it.

Make sure it is absolutely level and on a solid surface. It didn't loose a foot or pad underneath?

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I second this about leveling. Most just turn the adjusting wheel to zero it out and never consider the side to side leveling. If the beam doesn't have equal pressure on both sides it will not real true. Get a small bubble level and check the scale for level front to back and side to side. Clean the seats with rubbing alcohol and blow dry. Avoid any lube at all as it will make things sticky and attract dirt and dust.

I reread the OP and this made me scratch my head.

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Originally Posted by fnrockstar22

but both my beam scales have the same problem.
The problem is that when I zero them they will settle out for a second then start jumping around again.

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Low and mid priced electronic scales will suffer drift due to a number of factors but if a beam scale starts moving after it has settled there has to be a outside force acting on it such as a air current. Energy is needed to set a mass in motion.

Newtons first law - An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force."

Air currents, vibrations or a poltergeist, take your pick

Good catch SCdawg. Turn of the fan close the vents and breath a different direction.

So for clarification, Filing is never what I intended to say. The red ADT diamond hone is of decent quality it is flat and is a very fine grain of abrasive. removes material at a very slow rate.

If you take a loupe and look at the knife edges of your scale you will see imperfections. One big problem with beam scales is that people leave them assembled with the beam sitting on the base where the fulcrum is getting dull over time. They get banged around and such and this compounds the problem ending up with a scale that is inconsistent and that, is inaccurate.

If you have a scale that works as intended I recommend the practice of removing the beam carefully when not in use. A properly tuned and cared for beam scale can be unbelievable consistent and accurate.

Here are some tips that may also help. It is written primarily for the electronic scale use but many of the tips can be applied to beam scales

“14 Tips for Electronic Powder Scale Accuracy”By Lee Love

there are quite a few other sources for tips and techniques regarding weighing of charges. It is a popular topic on most shooting sites and forums and dozens can be found with a bit of searching

Quote:

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Originally Posted by Robinhood

Good catch SCdawg. Turn of the fan close the vents and breath a different direction.

So for clarification, Filing is never what I intended to say. The red ADT diamond hone is of decent quality it is flat and is a very fine grain of abrasive. removes material at a very slow rate.

If you take a loupe and look at the knife edges of your scale you will see imperfections. One big problem with beam scales is that people leave them assembled with the beam sitting on the base where the fulcrum is getting dull over time. They get banged around and such and this compounds the problem ending up with a scale that is inconsistent and that, is inaccurate.

If you have a scale that works as intended I recommend the practice of removing the beam carefully when not in use. A properly tuned and cared for beam scale can be unbelievable consistent and accurate.

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I understood what you meant. DMT, got it.

apologies on the filing misunderstanding, here is a example of a modded RCBS 502 weighing individual sticks of Varget

https://www.youtube.com/watch?v=g8VMBJXfYDE

5 sticks of extruded powder = appx .1 grain

It really sounds like an outside force if it keeps dancing up and down.

Might be draft, boiler going on and off, footsteps, etc.

Two more thoughts:

Ohaus (who make the RCBS/Hornady/Lyman/Lee, etc. beam scales scales) are magnetically dampened. If you have anything nearby with a strong magnetic field you may be impacting it.

I have my beam scale setting on a pane of glass removed from an old picture frame. As flat a surface as can be found in most homes.

A good test is to zero the scale, then weigh a bullet (I use Sierra MatchKings - they run very true to labeled weight) and reset to zero and see if it repeats the zero index. Or you could spend the $ on a scale standard weight kit.

Quote:

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Originally Posted by Stumpkiller

Two more thoughts:

Ohaus (who make the RCBS/Hornady/Lyman/Lee, etc. beam scales scales) are magnetically dampened. If you have anything nearby with a strong magnetic field you may be impacting it.

I have my beam scale setting on a pane of glass removed from an old picture frame. As flat a surface as can be found in most homes.

A good test is to zero the scale, then weigh a bullet (I use Sierra MatchKings - they run very true to labeled weight) and reset to zero and see if it repeats the zero index. Or you could spend the $ on a scale standard weight kit.

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Ive been doing that with my 60+ year old Reading for as long as i can remember.
But i make sure to weigh them first. lol
I also never disassemble it, it just sits on a shelf where its used, and left uncovered.
Could it be they don't make em like they used to?

I've had mine (RCBS 5-05 and 5-10) since before we were married - so 1975 to 1979 ish. Before that it was a Lee Loader on a pine board, mallet and powder dippers. ;-)