RCBS 5-0-5 Scale - Pan Weight Question

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Harvey Manfrenjensenden

Harvey Manfrenjensenden

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Hello & good afternoon all!

I have a question regarding the 5-0-5 scale. I received this scale from a gentleman at work who bought it with the RCBS RockChucker supreme kit a long time ago and he literally used it twice and it's been sitting in the factory packaging ever since. It's old enough that it's stamped "Made in USA" :thumbup: but I digress.

At any rate, I've done some work on the scale, such as honing the knife edges on the beam with a 1000 grit stone, (even stropped them) really cleaned up the agate bearings and polished their resting pads with Flitz I also polished the beam/tray hooks using Flitz as well so that I can be sure that the tray settles freely to the lowest point of the hook in a reasonably plumb setting.

My question (finally) is regarding the lead shot in the pan below the tray. I leveled the scale on my bench (which is also quite level) but I removed the shot, and used Duct Seal in the bottom of the pan. in doing so, I can keep the frame of the scale as level as possible and with the precise amount of compound in the tray it zero's out quite nicely on its own. I have to use the rotating foot plate just a hair when I pull it off the shelf and put it on the table between uses, but I'm talking just a little bit of a nudge for it to zero.

Duct seal (if you haven't heard of it) is like a tacky playdough, and I have it distributed in the bottom of the pan where the shot normally goes evenly and across the entire bottom. My thought process here was that it would help the tray on the hook plumb out without rolling weights being on one side or the other.

Yes, I realize I took a simple concept and probably overcomplicated it, (it's what I do, you should see me work on my Jeep). It seems to weight charges quite nicely, and is certainly on par in comparison to a (cheap) digital scale within a couple tenths of a grain, but my DS jumps a bit... It's not the "top of the line" model by any stretch of the imagination.

Do any of you who have more experience see any detriment in what I've done? I don't think so, but I want to be sure that I'm not overlooking something.
 
So you replaced the lead shot for duck seal? I don't understand why as long as the scale zeros it will work. But it the duck seal has moisture in it then that moisture could evaporate. Then the scale would not be accurate any longer.
 
Very good point daboone, a valid concern that I might not have completely thought through in the long term. My experience with duct seal comes from racing model cars, we use it for balancing wheels. For my short course truck its been on there for quite a while and it's still plyable/soft but it is a little bit dryer than it once was. I was thinking that any minor adjustments can be made with the foot, but now I'm thinking it's possible I may have created a moving target. Meh, these guys at RCBS know what they're doing, maybe I'll put the shot back in there. I just didn't want the shot on one side of the pan throwing it out of level. As I said, i tend to overcomplicate things ;)
 
Harvey Manfrenjensenden said:
maybe I'll put the shot back in there
Click to expand...
That's exactly what you should do. Don't forget the old, old, adage - "If it ain't broke, don't fix it."

daboone's point about moisture content changing the weight of the pan is the first thing I thought of also. The material you use might also gain weight if it is the least bit hygroscopic. So it can loose and gain weight at various times.

There is no good reason to try to "fix" the pan weight.
 
Check weights no, but I did take a couple of bullets at different weights, set them on my digital scale and let them sit there for a solid minute until the numbers settled and this scale was darn near spot on compared to that. Hardly scientific, but it's what I have at the moment.
 
Got it. What I did to get it to zero with keeping the scale as level as possible, is I took 3 hairs off of my dog and 4 grains of sand put them in the tray, then I rigged up a pulley to the ceiling with a fan pointed straight down at it and rigged the fan to blow at a constant 10.327 c.f.p.m. and adjusted the fan to be 4.629 feet above the tray...

Actually I just removed two of the larger pieces of shot and replaced them with a couple pieces of 20ga 7-1/2 shot.

KISS.

*edit*

I was re-reading my posts, and what I did not make clear at all was that one of my primary goals was to keep the frame of the beam as close to level as I could, and getting the beam to zero with the beam being level as well. With its prior configuration the beam was angled a little bit upward away from the tray.

Sorry about that folks, I didn't articulate myself well and didn't provide a clear understanding of "why" I starting messing around with it other than mentioning the frame/scale and using the word "level".
 
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Harvey Manfrenjensenden said:
It seems to weight charges quite nicely, and is certainly on par in comparison to a (cheap) digital scale within a couple tenths of a grain, but my DS jumps a bit...
Click to expand...
That's like trying to determine time with two watches. If your beam scale is off by .2 gr to digital scale but if the digital scale is off by .2 gr ... You know where this is leading ... :eek:

IMO, for reloading, especially at near max/max loads, we need accuracy and consistency of reloading scales with .1 gr resolution. Do we need less than that like .02 gr resolution? No, but .1 gr? Yes.

Harvey Manfrenjensenden said:
What I did to get it to zero with keeping the scale as level as possible
Click to expand...
The surface which the scale rests on needs to be level but the scale does not need to be level. Level surface allows the knife edges on agate bearings to better pivot without binding. And threaded foot allows adjustment for pointer to align with zero mark.

The key is repeatability of zero is better attained by knife edges pivoting freely without binding due to tilted bench surface. If your bench surface is not level, you can use a piece of flat plywood and use shims to level the piece of plywood.

Harvey Manfrenjensenden said:
What I did to get it to zero ... is I took 3 hairs off of my dog and 4 grains of sand put them in the tray, then I rigged up a pulley to the ceiling with a fan pointed straight down at it and rigged the fan to blow at a constant 10.327 c.f.p.m. and adjusted the fan to be 4.629 feet above the tray...
Click to expand...
NO. You DO NOT want any air movement when zeroing and operating a scale.

Instead, you should use a clear bowl over the scale to repeat zero by eliminating air movement.

Harvey Manfrenjensenden said:
I've done some work on the scale, such as honing the knife edges on the beam with a 1000 grit stone, (even stropped them) really cleaned up the agate bearings and polished their resting pads with Flitz I also polished the beam/tray hooks using Flitz as well so that I can be sure that the tray settles freely to the lowest point of the hook in a reasonably plumb setting.
Click to expand...
If you have done all these work to reduce friction on metal to metal/agate stone surfaces, your scale's repeatability should be good.

I currently use two Ohaus 10-10 scales but my RCBS 5-0-5 (which was PIF to a THR member) would detect 1-2 pieces of 1/4"x1/4" 20 lb copy paper and read 2-3 pieces around .1 gr.

In comparison, 10-10 would detect 1 piece of paper and read 2 pieces at around .1 gr. (Ohaus 10-10 in action weighing 2 pieces of paper and .15 - .3 gr check weights) - https://www.thehighroad.org/index.p...-busting-digital-scales.821449/#post-10551544

I strongly suggest you get a set of check weights.
 
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bds said:
That's like trying to determine time with two watches. If your beam scale is off by .2 gr to digital scale but if the digital scale is off by .2 gr ... You know where this is leading ... :eek:

IMO, for reloading, especially at near max/max loads, we need accuracy and consistency of reloading scales with .1 gr resolution. Do we need less than that like .02 gr resolution? No, but .1 gr? Yes.


The surface which the scale rests on needs to be level but the scale does not need to be level. Level surface allows the knife edges on agate bearings to better pivot without binding. And threaded foot allows adjustment for pointer to align with zero mark.

The key is repeatability of zero is better attained by knife edges pivoting freely without binding due to tilted bench surface. If your bench surface is not level, you can use a piece of flat plywood and use shims to level the piece of plywood.


NO. You DO NOT want any air movement when zeroing and operating a scale.

Instead, you should use a clear bowl over the scale to repeat zero by eliminating air movement.


If you have done all these work to reduce friction on metal to metal/agate stone surfaces, your scale's repeatability should good.

I currently use two Ohaus 10-10 scales now but my RCBS 5-0-5 (which was PIF) would detect 1-2 pieces of 1/4"x1/4" 20 lb copy paper and read 2-3 pieces at .1+ gr.

In comparison, 10-10 would detect 1 piece of paper and read 2 pieces at around .1 gr. (10-10 in action weighing 1-5 piece of paper) - https://www.thehighroad.org/index.p...-busting-digital-scales.821449/#post-10551544

I strongly suggest you get a set of check weights.
Click to expand...

Check weights already ordered! I knew going into this that it was a severely improper evaluation (same with my bullet weight comparison thing)

... See my last post. I didn't communicate well what all I was trying to accomplish, I wanted the beam to be as well balanced as I could get it on its own, and the frame to be as close to that as possible. I'm cool with making minor adjustments to the foot screw, but I wanted some assurance that the beam with the tray et al was balanced.

Was it necessary? Probably not. If you have it "zeroed" and in reality it's at 15 grains over/under, it probably wouldn't matter. 41.9 grains of weight over that is 41.9 grains of additional weight but I felt that it was possible that the geometry could present issues. Maybe I'm wrong, but I feel better now.

"NO. You DO NOT want any air movement when zeroing and operating a scale.

Instead, you should use a clear bowl over the scale to repeat zero by eliminating air movement."

Sorry, sometimes I lay the sarcasm/humor on a little thick especially when it comes to making light of my own shortfalls and mistakes.

Question for a hypothetical scenario - let's say I put the check weights on the scale and it reads with a deficiency or in excess, what would the procedure be? Note the difference and adjust the slide weights accordingly?

Here is where my mind goes with regards to that, and by all means lay it on me if I'm way off track... lf I'm working up a load, I'm throwing charges in .2gr increments. I'm going to find a charge that works for that particular rifle/bullet. As long as the scale is consistent & repeatable and I use only it for the forthcoming charges for that load, will it matter if it's true value/reading is off? (This is of course assuming that it's not 10 grains off, where my starting load of 40gr is actually 50)

Example, I'm going for 40, 40.2, 40.4 & 40.6

Scale true/actual is 40.1, 40.3, 40.5 & 40.7

Field test shows 40.4 is my ideal charge. Yes, it's actually 40.5 but as long as I use this scale for that charge, and I don't use another scale to work up the same load, wouldn't it be a relative issue and not so much an issue of an improper charge weight? (I should note, very rarely do I end up at max-charge with exception to working up a load, but I usually go with the more consistent lower accuracy node)

Between the mechanical scale and the little Frankford Arsenal digital, worst case scenario is that I would be off 4 tenths of a grain so I know I'm not developing loads that are 5 grains over or anything like that, but again I say; hold nothing back If my thinking is going to get me or someone else on the range in trouble. We already know I'm the type of idiot that sticks silly puddy in his scale :)
 
Harvey Manfrenjensenden said:
Question for a hypothetical scenario - let's say I put the check weights on the scale and it reads with a deficiency or in excess, what would the procedure be? ... This is of course assuming that it's not 10 grains off, where my starting load of 40gr is actually 50
Click to expand...
Your .1 gr resolution beam scale should read same as check weights in the powder charge range you are using. And if the difference was less than .1 gr, I would be OK.

If the difference was consistently more than .2 gr+, I would invoke the warranty or replace with a scale that consistently read to .1 gr and within .1 gr of check weights.
Harvey Manfrenjensenden said:
Between the mechanical scale and the little Frankford Arsenal digital, worst case scenario is that I would be off 4 tenths of a grain ... hold nothing back If my thinking is going to get me or someone else on the range in trouble.
Click to expand...
While .4 gr may not seem much for rifle loads, keep in mind that some pistol powders have start/max charge range of only .5 gr.

If buying used scales, using 1/4"x1/4" pieces of 20 lb copy paper is a good way to test sensitivity and repeatability of scales. If the scale can detect one piece and consistently read 2 pieces around .1 gr, I would buy it.
 
I didnt modify any of mine from their factory condition and they are accurate however the pan sits and even if it's rocking a little from me setting the pan back on.

Like this.



Note the swinging the pan is doing while the 2nd charge is dropped in and the fact that it's still right on. Sitting to one side or the other wouldn't matter if you can effectively be sitting on both sides and in the middle with the same reading.
 
bds said:
Your .1 gr resolution beam scale should read same as check weights in the powder charge range you are using. And if the difference was less than .1 gr, I would be OK.

If the difference was consistently more than .2 gr+, I would invoke the warranty or replace with a scale that consistently read to .1 gr and within .1 gr of check weights.

While .4 gr may not seem much for rifle loads, keep in mind that some pistol powders have start/max charge range of only .5 gr.

If buying used scales, using 1/4"x1/4" pieces of 20 lb copy paper is a good way to test sensitivity and repeatability of scales. If the scale can detect one piece and consistently read 2 pieces around .1 gr, I would buy it.
Click to expand...

20lb copy paper, hmm. I have that, I'll give it a try. Check weights are on the way but I'm curious about this for in the meantime. The scale appears to be working well, when I'm trickling a charge and I'm just a hair under, I'm seeing very subtle movement with one kernel of h4350, but I would like to know if it's reading true for sure.
 
jmorris said:
I didnt modify any of mine from their factory condition and they are accurate however the pan sits and even if it's rocking a little from me setting the pan back on.

Like this.



Note the swinging the pan is doing while the 2nd charge is dropped in and the fact that it's still right on. Sitting to one side or the other wouldn't matter if you can effectively be sitting on both sides and in the middle with the same reading.
Click to expand...


Thank you! That's reassuring. I worked up some loads last night between 41 and 42.4 grains and at the end I adjusted the slide weights back to 41 and dumped the powder out of one of my first cases and it was dead on. So relatively speaking and within the constraints of this particular scales (possible) inherent error, it at the very least appears to be consistent within itself.
 
On duct seal- a heating and a/c product
Divers call it "monkey sh--"
We use it u/w to seal holes when making repairs and during salvage ops.
 
Well, I'm going to call the 20lb paper test somewhat successful. Verified zero, set it for .10 grains and the scale came up and just about split the line. It may have been off by a... uhmhmm, "hair" ;) so once the check weights get here I'll recheck it closer to my charge weight.

Do you folks want to hear about one of the worst cases of irony yet? In my research and learning as much as I can about these scales, the name Scott Parker has come up a whole bunch. Apparently he works some serious magic with these older scales, but I decided to give it a go myself.

Turns out... Scott Parker lives a couple blocks away from me. o_O
 
Turns out... Scott Parker lives a couple blocks away from me.
Click to expand...

I have tried to get ahold of him a few times and I think I got a reply once but unsuccessful with a dialogue.

I would be willing to send one to him just to be able to see what his renowned tune is comprised of. He is held in high regard among the Ohaus scale tuners.
 
How ironic!

Good to hear about your 1/4"x1/4" 20 lb paper test. USA made Ohaus and RCBS beam scales have good reputation for accuracy and consistency.

If your scale is sensitive and consistent with the paper test, it should do well with the check weights as smallest of them usually only go down to .5 gr.

I have the Ohaus ASTM Class 6 check weight set and 1 mg (0.015 gr) check weight won't register with my .02 gr resolution Gemini-20 digital scale; however, 10 mg (0.15 gr) check weight will register as .14/.16 gr along with Ohaus 10-10 - https://www.zoro.com/ohaus-calibration-weight-set-500-to-1mg-80850110/i/G0843236/
 
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