A little scale experiment

[BoydAllen]

Yesterday I did a little experiment that I had been meaning to for a long time. The equipment used was a self tuned RCBS 10-10 scale, an inexpensive (less than $10 from Ebay) manual focus webcam, a Bald Eagle digital scale, a Dandy Products Handy View Beam Scale Prism, and some stick powder (AR-Comp) that was handy at the time, oh and my computer. The goal was to determine just how accurate charges that I had trickled were, using the prism and then the webcam, with the image viewed on my computer's monitor.

The first thing that I needed to know was how reliable the readings of the scale were, weighing the same item repeatedly. I used the scale pan with the weight of powder that I had chosen for the test (30 gr.). I did not tare the pan but viewed the total weight so that I could see that the scale returned to zero after every weighing. I think that I may have tared the scale one time when it did not return. The extreme spread of weights, for seven weighings was .03 gr.

Next I use the prism, which is designed to allow one to have a straight in view of the scale's pointer and reference mark with the scale on my desk without having to stoop down to read it properly. The extreme spread of readings with this method was .2 gr. I did my best to keep my head in the same position for each reading.

Next I set up the webcam and used it to read the scale. Carefully measuring the block 0 by the reference line on the scale and comparing it to its image on the screen I found that the image was magnified a little over 6X. If I had gone to full screen, it would have been a little over 7X. Being very careful to put the pointer exactly even with the reference mark on the scale, and redoing a couple of over trickles, the extreme spread of weights was .03 gr., the same as the scale repeatedly weighing the same thing had been. I was at the limit of my tools and would need a better scale if I wanted to learn more about the accuracy of my setup. A friend has a better scale and in the next month or so he said that he will bring it over. As with the others, I weighted seven charges.

Finally, I decided to see if taring the scale every time, and weighting the same thing repeatedly would give me a better extreme spread. It made it worse. The ES was twice what it had been, .06 grains.

The way that I did each 30 gr, charge after trickling up to the first one was to pour a little powder from the scale's pan back in the trickler, and then trickle up to the desired weight.

When I have my friend's scale, that reads to three places in grains, I will also try my Dandy Products trickler which should theoretically give me better control when adding the last few pieces of powder to a charge. At the moment, my scale is the limiting factor, and I am able to work to its limits with the old RCBS trickler.

Any comments are welcome. Yes I know the samples were small, but I think that I could easily see the trends. I hope that this little test may be of some use to a few of you.

 

[T-shooter]

That's the way. Test everything. I don't know how accurate or reliable that electronic scale is. I've only had two decent electronic scales before getting the FX scale. It will weight the same thing the same day after day with no variation. The others were both Gem-Pro 300's. One seemed better taring each reading and with the other, it didn't matter. The accuracy 99% of the time was +/- .02 grain. I also use the Dandy trickler. It's easy to drop small amounts, even 1 kernel of Varget at a time on slow mode.

I went the route with a Hornady beam scale. I thought it was accurate because I could see .02 grain change. What I didn't know was when the beam and it's pivots were offset sideways, it would weigh as much as 3/10 grain spread. I reworked it with small roller bearings but it still seemed to do somewhat the same. Even tried taking the magnets out which made no difference except it took forever for the beam to come to rest. I gave up and went electronic.

It will be interesting to check your scale's accuracy with your friends balance that reads to .002 grain, or .0001 gram. I had a cheap one once and it was a pain to use. Everything upset it.

 

[BoydAllen]

IMO the bearing system of the US made RCBS/Ohaus scales is superior to what Hornady offers. I played with a Hornady and decided that it did not have the potential to do what I wanted.

 

[ballisticdaddy]

Curious in reading through this I did not see any mention of check weights, how are you ensuring the value is accurate?

 

[BoydAllen]

I was not that concerned with accuracy because I know that the scales are very close to each other and that the 10-10 was OK when I weighed the 250 grain auxiliary weight. All of my scales are close enough that as long as I stay with the same scale for a given task, I am good to go. For me, the experiment was about how much difference there would be between an unmagnified reading of the scale and one that had no parallax and was magnified 6X. So far, my self tuned scale is as good as my electronic scale can "see" and I plan on using my friend's scale to see if I am actually getting better results than that. Stay tuned.

 

[sparker]

I was not that concerned with accuracy because I know that the scales are very close to each other and that the 10-10 was OK when I weighed the 250 grain auxiliary weight. All of my scales are close enough that as long as I stay with the same scale for a given task, I am good to go. For me, the experiment was about how much difference there would be between an unmagnified reading of the scale and one that had no parallax and was magnified 6X. So far, my self tuned scale is as good as my electronic scale can "see" and I plan on using my friend's scale to see if I am actually getting better results than that. .

A customer of mine in Denton TX used a very costly lab scale that read to .001 grains to check the results of 20 charges measured with a tuned Redding that I supplied. The SD was .016. Essentially one kernel

 

[BoydAllen]

To clarify my earlier remark, The only thing that I have done to my scales is to make them more sensitive. They return to zero quite reliably, and seem to be able to show very small differences in weight, a single piece of stick powder. The reason for this test was to see how consistent trickled charges were, using two methods of reading the scale. What I found was that with the webcam, results were as consistent measuring seven charges of the same weight as with weighing one charge seven times. To learn more I will need a better electronic reference scale. Preliminary results seem to indicate that if your setup is a tuned balance read with a webcam that your charge consistency can be quite good, probably good enough for any application.

 

[SteveOak]

Do you think it would be any easier/better/more repeatable/reliable with a cross hair superimposed on the lines?

 

[BoydAllen]

It probably would go faster with a more sensitive trickler like the Dandy, because there would be fewer overshoots and the cross hair would probably make seeing when things are perfectly lined up easier. I have the trickler, and if I remember correctly the software with the cross hair is a free download. I forget where the link is. Could you post it?

 

[SteveOak]

Yep, freeware.

Here you go Boyd.

https://www.sharpcap.co.uk/

You said you might try a Dandy trickler. Which trickler were you using?

 

[BoydAllen]

I have an early production auto tricker somewhere up on a shelf in my closet. When I get my friend's more accurate scale, I suppose that I should test it to see how well it works. For now I will just use it like one of their regular tricklers. The truth is that I have always gotten by pretty well with my RCBS that has the base poured full of lead.

 

[MagnumManiac]

I have one of those Hornady beam scales, verifyed by 2 electronic and 3 other brand beam scales and that Hornady scale of mine reads 1.2gr LIGHTER than the actual weight. Meaning that a max load is actually 1.2gr higher than what it should be. I used that scale for several years without ever check weighing it.
My bad...

Cheers.

 

[CharlieNC]

Boyd when I did essentially the same test on my tuned Redding the weight range was .06gr. Also using the Bald Eagle as the reference I found it necessary to tare every time, and the drift did not show up as a deviation in zero. It appears that knife edge bearing friction still causes the deviations.

Same test on Chargemaster yielded amazing .03gr range!

 

[BoydAllen]

On home made check weights: Some years back when I was able to use a friend's electronic scale, one of some quality ($300+) but not a magnetic force restoration scale, I weighed some different coins noted their weights, wrapped them in that paper, held in place with a paper clip. The weights of the coins were very close on my balance scales. If you have a friend with a fancy scale, these days it might be better than the one that I used, you can do something similar, and possibly include some slightly heavier objects like bullets and cases.

 

[CaptainMal]

I have check weights and an A&D FX 120i. Also have three Lyman M5's and a small digital plus two more on Lyman and Hornady dispensers. I have the stuff to weigh and check. Have played around and found out something about the three M5's. Now none are Parker tuned but the bearing surfaces seem crisp. What I found out is they weigh different adding grains to the pan compared to removing grains from the pan.

Seems that they are more repeatable than absolute, depending on which way you are going. You overfill the pan and try to remove a kernel at a time and all three of the M5's hang up.

If other scales like that are the same, I would question their absolute weighing ability.

 

[BoydAllen]

A customer of mine in Denton TX used a very costly lab scale that read to .001 grains to check the results of 20 charges measured with a tuned Redding that I supplied. The SD was .016. Essentially one kernel

I would like to point out one thing here. Targets see ES. and that is the only number that concerns me be it velocities or charge weights. Generally sample sizes are too small for SD to have much validity, but because chronographs include that in their readouts they are referred to in shooting related posts, articles and videos all the time. I think that this has obscured rather than clarified results. When I read your post, the first thing that came to mind, after being glad that you had shared the information, was to wonder what your ES had been.

When I test a scale weighing the same object, if I have one weighing that extends the spread, I do not throw that out because I would not know that it had happened if I was weighing a series of objects or charges. Similarly it will be the extremes of velocity that would probably be my most divergent shots in a group shot at long range. There is no provision for scoring the SD of bullet impacts. Thank you for posting. I hope that my response has not offended you.
Boyd

 

[swadiver]

i

Yesterday I did a little experiment that I had been meaning to for a long time. The equipment used was a self tuned RCBS 10-10 scale, an inexpensive (less than $10 from Ebay) manual focus webcam, a Bald Eagle digital scale, a Dandy Products Handy View Beam Scale Prism, and some stick powder (AR-Comp) that was handy at the time, oh and my computer. The goal was to determine just how accurate charges that I had trickled were, using the prism and then the webcam, with the image viewed on my computer's monitor.

The first thing that I needed to know was how reliable the readings of the scale were, weighing the same item repeatedly. I used the scale pan with the weight of powder that I had chosen for the test (30 gr.). I did not tare the pan but viewed the total weight so that I could see that the scale returned to zero after every weighing. I think that I may have tared the scale one time when it did not return. The extreme spread of weights, for seven weighings was .03 gr.

Next I use the prism, which is designed to allow one to have a straight in view of the scale's pointer and reference mark with the scale on my desk without having to stoop down to read it properly. The extreme spread of readings with this method was .2 gr. I did my best to keep my head in the same position for each reading.

Next I set up the webcam and used it to read the scale. Carefully measuring the block 0 by the reference line on the scale and comparing it to its image on the screen I found that the image was magnified a little over 6X. If I had gone to full screen, it would have been a little over 7X. Being very careful to put the pointer exactly even with the reference mark on the scale, and redoing a couple of over trickles, the extreme spread of weights was .03 gr., the same as the scale repeatedly weighing the same thing had been. I was at the limit of my tools and would need a better scale if I wanted to learn more about the accuracy of my setup. A friend has a better scale and in the next month or so he said that he will bring it over. As with the others, I weighted seven charges.

Finally, I decided to see if taring the scale every time, and weighting the same thing repeatedly would give me a better extreme spread. It made it worse. The ES was twice what it had been, .06 grains.

The way that I did each 30 gr, charge after trickling up to the first one was to pour a little powder from the scale's pan back in the trickler, and then trickle up to the desired weight.

When I have my friend's scale, that reads to three places in grains, I will also try my Dandy Products trickler which should theoretically give me better control when adding the last few pieces of powder to a charge. At the moment, my scale is the limiting factor, and I am able to work to its limits with the old RCBS trickler.

Any comments are welcome. Yes I know the samples were small, but I think that I could easily see the trends. I hope that this little test may be of some use to a few of you.

Yesterday I did a little experiment that I had been meaning to for a long time. The equipment used was a self tuned RCBS 10-10 scale, an inexpensive (less than $10 from Ebay) manual focus webcam, a Bald Eagle digital scale, a Dandy Products Handy View Beam Scale Prism, and some stick powder (AR-Comp) that was handy at the time, oh and my computer. The goal was to determine just how accurate charges that I had trickled were, using the prism and then the webcam, with the image viewed on my computer's monitor.

The first thing that I needed to know was how reliable the readings of the scale were, weighing the same item repeatedly. I used the scale pan with the weight of powder that I had chosen for the test (30 gr.). I did not tare the pan but viewed the total weight so that I could see that the scale returned to zero after every weighing. I think that I may have tared the scale one time when it did not return. The extreme spread of weights, for seven weighings was .03 gr.

Next I use the prism, which is designed to allow one to have a straight in view of the scale's pointer and reference mark with the scale on my desk without having to stoop down to read it properly. The extreme spread of readings with this method was .2 gr. I did my best to keep my head in the same position for each reading.

Next I set up the webcam and used it to read the scale. Carefully measuring the block 0 by the reference line on the scale and comparing it to its image on the screen I found that the image was magnified a little over 6X. If I had gone to full screen, it would have been a little over 7X. Being very careful to put the pointer exactly even with the reference mark on the scale, and redoing a couple of over trickles, the extreme spread of weights was .03 gr., the same as the scale repeatedly weighing the same thing had been. I was at the limit of my tools and would need a better scale if I wanted to learn more about the accuracy of my setup. A friend has a better scale and in the next month or so he said that he will bring it over. As with the others, I weighted seven charges.

Finally, I decided to see if taring the scale every time, and weighting the same thing repeatedly would give me a better extreme spread. It made it worse. The ES was twice what it had been, .06 grains.

The way that I did each 30 gr, charge after trickling up to the first one was to pour a little powder from the scale's pan back in the trickler, and then trickle up to the desired weight.

When I have my friend's scale, that reads to three places in grains, I will also try my Dandy Products trickler which should theoretically give me better control when adding the last few pieces of powder to a charge. At the moment, my scale is the limiting factor, and I am able to work to its limits with the old RCBS trickler.

Any comments are welcome. Yes I know the samples were small, but I think that I could easily see the trends. I hope that this little test may be of some use to a few of you.

Your experiment prompted me to do the same with the equipment i have.

Scott Parker tuned Ohaus 10-0-5 (same as a Lyman M5) , pencil lead burnished on the knife edges mod, very small needle glued to the indicating end of the poise, really good led lighting

Lyman 30gn check weights

Web cam pointed at the indicating needle on the poise hooked up to view on a tablet computer.

using the 30 gr check weights, i removed and replaced the pan with the weights ten times in a row and saw the exact same indication on the scale every time. i mean exact. with needle glued on and the use of a web cam, one is able to see the smallest detail and movement. a single grain of IMR 8208 XBR is readily seen on the scale.

i also have an A&D FX-120i, which i use in conjunction with Lyman when loading mid and long range match ammo. I like to double weigh my match charges. i normally "throw" the charge a tenth of a grain under on my Chargemaster Lite, trickle as needed onto the Ohaus with a Dandy two speed trickler, and double check the charge weight on the FX-120i. using two pans for this operation, is moves very quickly. a note on the Chargemaster Lite that i just received and started using: i don't find it repeatable enough to be used on it's own for mid and long range match ammo. works great as an accurate charge thrower, however.

some may find this procedure overkill. that's ok. i am admittedly anal about this kind of stuff. if i am just loading for short range, i just use the Chargemaster and the Ohaus

 

[sparker]

I would like to point out one thing here. Targets see ES. and that is the only number that concerns me be it velocities or charge weights. Generally sample sizes are too small for SD to have much validity, but because chronographs include that in their readouts they are referred to in shooting related posts, articles and videos all the time. I think that this has obscured rather than clarified results. When I read your post, the first thing that came to mind, after being glad that you had shared the information, was to wonder what your ES had been.

When I test a scale weighing the same object, if I have one weighing that extends the spread, I do not throw that out because I would not know that it had happened if I was weighing a series of objects or charges. Similarly it will be the extremes of velocity that would probably be my most divergent shots in a group shot at long range. There is no provision for scoring the SD of bullet impacts. Thank you for posting. I hope that my response has not offended you.
Boyd

Hi Boyd. I presented the data as it was relayed to me. Of course SD in non-pathway dependent. So, the value listed could be had by 19 perfect weights and one imperfect weight that was sufficiently large. Conversely, the value can also be had by several very small imperfections. However, I think the real question in all of it is this: was the lab scale checking the Redding or checking the operator?

I have no doubt that there are some fine digital scales out there in use by shooters. There is however no acumen required for their use. An oscillating beam on the other hand requires some knowledge about how they work in order to use them most efficiently and accurately.

 

[dminn1]

Does one kernel of powder contain the same energy potential as the next one?

 

[BoydAllen]

Hi Scott,
If my shooting was not all short range, and even if it was, if my shooting budget was larger, I would have a magnetic force restoration scale, but since I do not, and I have a high opinion of the capability of tuned scales, I was curious about what the equipment that I have is capable of, when operated with great care. I am encouraged that people have taken the time to respond and post their own stories. The tricky part in all of this is figuring out what your limiting factor is, because that is the one that you need to put the most effort into correcting. Given that I have seen top level, short range group matches won, and world records set with thrown charges, this test is not a matter of practical necessity for me, but that has no effect on my curiosity.
Boyd