Improving the RCBS 5-0-5 beam scale accuracy

[sandro.1971]

I have a RCBS 5-0-5 scale and I think this scale has important defects that should be fixed. As it is, this scale looks to me like a cheap China made scale. You could ask why did you buy it, well I just find it included in the RCBS reloading kit otherway I wouldn't have taken it.

1) First of all the scale body is so light (aluminum made) that you have to be very careful each time you lift the pan, set it back or move the poises. Each time you perform one of the actions above you risk to move the whole scale and loose the zero.

2) When you remove the pan, set it back or move the poises the beam tend to rotate or move in the front-back direction. If you are not careful the beam will slide and the pivots will go against the sides (front or back) of the bearings; this of course will affect accuracy.

3) The beam hasn't any damping system (I mean not at the zero but up/down) so if you you remove the pan, set it back or move the poises the beam will hit (up or down) against the scale body. This of course will affect accuracy.

4) The levelling foot is really poorly made and its screw has a big play in the nutscrew.

Since I had this scale and I was not satisfied about it I thought that I could resell it or try to improve it and I finally went for the second choice.

I took a plexiglas sheet and cut 2 caps from it. I used some glue to fix them to the scale body and filled the space between the caps of lead shoots (about 3lbs).
The upper cap is used to avoid that shots could enter the space between the magnets of the zero damping system.



I took one earmuff and put it on the scale body right under the left end of the beam. It makes a perfect damping system for the beam so you don't have the beam hitting against the scale body every time you remove the pot.



Finally I used some teflon tape to reduce the levelling foot screw play.

[WSM MAGNUM]

Sounds like some neat improvements you made. I use to have an RCBS 5-0-5 It has been so long ago though. I don`t remember it being made so cheaply made though. I thought RCBS equipment was still American made? I don`t remember mine being cheapy. It worked real good and I later upgraded to the 10-10, which I still use.

[mikenbarb]

I believe the majority af scales for the big 5 are made by Ohaus. Nice improvements you made and its a great simple fix you found. Im gonna put an ear plug on my Dillon rite now. Thanks, Cool idea.

[brickeyee]

3) The beam hasn't any damping system (I mean not at the zero but up/down) so if you you remove the pan, set it back or move the poises the beam will hit (up or down) against the scale body. This of course will affect accuracy.

The aluminum blade in the slot behind the beam is a magnetic damper.

The frame has a magnet set in it, and when the aluminum blade moves in the magnetic field it creates eddy currents that damp the motion.

Once the motion comes to a halt the magnetic field has no affect on the reading of the scale.

[Yoosta B. Blue]

Thanks for sharing the enhancements that you made for the 5-0-5 scale. I'm not following you on the plexiglas caps that you mention. Are they placed inside the scale body?

Yoosta B. Blue

[wncchester]

It's unlikely that a small displacement of the scale while using it on any reasonably level surface will affect the zero at all. Obviously, shifting the poise weights will!

Improved stability is a good thing for any scale. I have never ballasted a scale with lead shot but I have several by filling the casting cavity with plaster of paris. The plaster works fine, is easy to find in many hobby supply stores and is very inexpensive. Just don't drop any weighted scale, it will almost surely break the body casing. I suspect the additional weight voids any warranty too.

You really don't need any caps to prevent any non-magnetic material, including lead shot, from entering the left end around the damper magnet. Such material has absolutely no effect on the magnetic field so it has no effect on either dampening or accuracy.

[sandro.1971]

Yoosta B. Blue, the caps are basically 2 rectangles and they are placed inside the scale body to hold the shots.

As Wncchester says, the lower cap would be enough since shots are not-magnetic and it's not a problem if they fill the space between the magnets.

When I say "loosing the zero" I mean that if you adjust the levelling foot and zero the scale, remove the pot and put it back sometime you don't have the zero again. I read this happen to many people on different scales.

I think this is also due to poor scale stability that causes front-back movements of the beam. The beam tend to slide (front or back) and the pivots ends can touch the sides (front or back) of the bearings.

[mikenbarb]

Sandro, If your scales doing that, its got a problem because their not supposed to lose zero by just removing and replacing the pan. Check the knife edges and see if their nicked or something in the beam pivot holder thats affecting it. It should never lose zero at all if you dont move it from where you zeroed it.

[Steve in PA]

I've been using the same scale for almost 18 years now, just as it came out of the box. Never had a problem or issue with the scale.

I've never lost zero by taking off and replacing the pan.

[sandro.1971]

Several people in several forums report this problem about their scales (not just the 5-0-5 but also other brands/models).

If you check your scale pivots you'll see that knives can slide in front-back direction even if they'll stay perfectly centered in the left-right direction (because of the V they cannot move left-right)

If knives slide too much they can touch pivots walls (front or back) and this will create a resistance that will affect accuracy of your measurements.

Now if the beam hits against the scale body (it always happens when you remove the pan or put it back ) and bounces a little the knives can slide.

The V shape of the pivots is a self centering system for the "left-right" direction but there is no self-centering system for the "front-right" direction.

Also if the scale is not stable because its body is too light when you move the poises the scale may move and the zero will be affected.

[wncchester]

Sandro - "When I say "loosing the zero" I mean that if you adjust the levelling foot and zero the scale, remove the pot and put it back sometime you don't have the zero again. I read this happen to many people on different scales."

That's true, sorta. You aren't really losing zero, what you have is a loss of freedom of beam movement due to friction when the pivot shaft rubs against the bearing holding clips. That dragging has the effect of changing both zero and accuracy but it's not a loss of zero as such.

"If you check your scale pivots you'll see that knives can slide in front-back direction even if they'll stay perfectly centered in the left-right direction (because of the V they cannot move left-right)"

Exactly right! I stopped most of that binding on my scale by grinding a tiny slant at each end of the pivot beam, just above the knife edge. Now, even if I shift the beam so it rubs against a clip, it has a minimum of contact and that's located at the pivot point. That greatly reduced the amount of end friction and it didn't take much grinding. I just changed the end angle from 90 to maybe 85 degrees above the knives. End grinding like that should work on any simular scale.

[sandro.1971]

Wncchester, your idea about grinding the beams is another good improvement that I had not thought about.

Thanks for sharing

[mikenbarb]

This is good to know and I have never had the problem with mine but now I know how to fix it if I do.

[mkl]

Sandro:

Can you check your 5-0-5 and find out where it was made?

Recent posts have allegations that current RCBS scales are made in China.

I've got an RCBS 5-0-2 that says on the box "Manufactured exclusively for RCBS by Ohaus Corporation." Neither it nor my 35 year old Lyman/Ohaus has the problems you describe.

I'm just wondering if RCBS has compromised quality for cost on their current vintage of beam balance scales.

[sandro.1971]

mkl, my scale is manufactured exclusively by Ohaus Corporation

[mkl]

mkl, my scale is manufactured exclusively by Ohaus Corporation

Okay, let's go to step two. On the bottom of the box my 5-0-2 came in, it says " Made in U.S.A." Does your 5-0-5 say that on the bottom of the box?

United States import law states that if the product is not made in the U.S.A. that the country of origin must be stamped on the product. If Ohaus is now sourcing scales from China, the origin stamp would be on the box or on the underside of the scale body.

I have a hard time believing that a firm a reputable as Ohaus would source scales from China, but you never can be sure... Black & Decker tools for example.

I really would like to see if someone could put this "Made in China" rumor for current balance beam RCBS scales to rest.

[sandro.1971]

I can't see the bottom of the scale body right now because it's full of lead shots and there's a cap glued there to hold the shots. I should remove the glue and the cap.

But from what I remember there's a Made in USA written there.

Anyway I think either it's made in USA or CHINA wouldn't change much.
Many electronics products like computers, phones and cameras come from China and they work fine. This is not a production issue but a design issue.

The earmuff is so soft that when removing the pot the beam is stopped very very slowly and I can see that the zero is held much more consistently.

[mikenbarb]

Buy AMERICAN, Your job may depend on it someday.

[DEDON45]

Hmm... I like the earplug idea, and weighing the scale down... methinks I'll be tinkering with my Hornady scale (made in much the same way)...

[sandro.1971]

mkl, I just read it on the scale box. It says "MADE IN MEXICO"

[gun44]

I have used since 1974, and never a moment's trouble with it! I also have an extra 5-0-5 scale just to compare weights with the older one once in a while, and both weigh within one tenth of a grain of each other , and both are accurate with the weight checks from RCBS. I have tried the Lyman scales, and the Lee scales, and neither compare with the RCBS. Maybe you have a dud?

[mkl]

Sandro:

mkl, I just read it on the scale box. It says "MADE IN MEXICO"

Thank you for the information. Most of the stuff I've seen made in Mexico exhibits good quality control, as opposed to China which is all over the map.

[WESHOOT2]

My Lyman Scale Weight Check Set, which cost under $30, fixes my 505 every time I use it.......

[sandro.1971]

mkl, the RCBS Chargemaster 1500 is made in China.

But I have to say it works perfectly.