Chargemaster Test

Very well stated Boyd.
When all the dust settles, it all comes down to what you know and can make needed adjustments to; to make it work for you. I like the Chargemaster, but agree that it is a PITA at the range - which is why I load vials at home. The danger of that is, I can not change my load when I get to the match - which is why I use a tuner. I believe in this system but also understand (crystal clear) that there are other systems that are just as good or better. If/when I find a better system- I will switch.

Mr. Elliot, I do not know why it happened - just that it did. And...I never would have known this if I wouldn't have had access to this scale.
 
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I'm with the Old Bald Guy

I do not see how the fullness of the hopper, or the absence of a baffle, have any effect on the chargemaster. These are holdover thinking from powder measures and the perceived effects are really the result of something else. I grounded the frame of my Chargemaster combo and it will throw the same weight every time, with fine ball powders at least. Rarely it will go over, and that is due to the clumping of powder in the trickler tube. What happens is that it trickles out the required charge and stops rotation of the tube, but then a clump breaks off and it goes over. If you pick up the pan right away, you will not notice this. You have to wait for it to give you the round count, then give the weight a second time, in order to get the true weight. This effect is worse with long grain powders like Varget. You might be dispensing 43.5 grains. Then one of those random clumps breaks loose at the critical moment and you get 43.6 or 43.7 grains. I generally dump a tiny bit back in the hopper and trickle more out til I hit the charge I want. You must pick up the pan and put it back down squarely. Either that, or throw the whole charge back in the hopper and redispense. Picking a little out of the pan totally messes up the scale from static and pressure effects. If you don't trust your Chargemaster, keep a few check weights handy and deploy them every few charges. If the weights vary, you might want to address your static electricity problem before you blame the Chargemaster.
 
This might be interesting. Some time when you know that you will not be loading for a week. fill the hopper of your Chargemaster to your preferred fraction of fill, using a powder from a freshly opened new container. Set the it for whatever load that you think appropriate, measure ten charges saving them into a suitable container, and then weigh the whole batch using the scale by itself. Then dump the powder back into the hopper, leaving it there. with something over the top that will keep out the dust, and stray sparks, but let the contents breathe. Then do the same thing (with the powder that has stayed in the hopper) a week later, and see if there is a difference in the weight.
 
Trust your check weights

Whatever type of electronic scale you use, a set of check weights, kept in a dust-proof case, and handled with tweezers, will not lie! Deploy them frequently and load with confidence (or get a new scale).
 
Just a guess but - - -

I have come to the conclusion that one can not rely on each curnel of powder weighing the same and this may be why there are deviations in charges, be they thrown or trickled as a Chargemaster does. I remain unconvinced, with the powders I use, that the node I am on will forgive any variation at all and I try for none. Of course, I am retired, load at home in Airconditioned comfort and have plenty of time. The powders I use don't need to be tweeked much, I don't beieve.
 
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testing

testing


I've run dozens (hundreds?) of hoppers through my Chargemaster and have never noted a variance in accuracy from full to empty.

al
 
alinwa said:
​

testing

testing


I've run dozens (hundreds?) of hoppers through my Chargemaster and have never noted a variance in accuracy from full to empty.

al
Click to expand...

Me either, but I also weigh the charges on my AcuLab after. I just use the CM as a dispenser and a power trickler to finish, if necessary. My Chargemaster is about 90% dead nuts accurate but it's the odd one, just like RF ammo, that will spoil your day.
 
Pete Wass said:
Me either, but I also weigh the charges on my AcuLab after. I just use the CM as a dispenser and a power trickler to finish, if necessary. My Chargemaster is about 90% dead nuts accurate but it's the odd one, just like RF ammo, that will spoil your day.
Click to expand...

That does just change one's perception doesn't it Pete :) :)

For me, it's a comfort to KNOW.

I've got three scales set up in the room, three throwers, a battery of checkweights, a dozen marked cartridges and 4 identically weighted scale pans. When we have agreement acros't that spectrum days/weeks/months/YEARS in a row,

it's a comfort.

AND, when single digit ES is routine,

it's a comfort.

It just makes it easier to sort out the chaff..... as you well know.

LOL

al
 
Larry Elliott said:
I can understand how the level of powder in a measure can affect the thrown charge, but have a little difficulty understanding how the level of powder in the "trickler" can have an effect on the weight of powder dispensed onto an electronic (or any other) scale. Any theories are heartily welcomed.
Click to expand...

Seems curious to me, too. Maybe with the fuller hopper, the grains are jammed together such that they don't flow into the opening in the rotating tube as well??? I have noticed that overcharging usually is associated with a big clump of grains being dumped into the pan right as it is approaching the correct weight. I get fairly frequent overcharges with 4198 (~ 1 in 10). Maybe covering part of the inlet hole on the rotating tube would reduce the amount of powder in the tube and the number of clumps. Would probably increase the time for trickling the charge, too.

Jason, I did an ANOVA on the deviations from the mean, and the difference in results between the two hopper fills is statistically significant (p<0.01), so it appears that this is not just a random effect.

Cheers,
Keith
 
Apollo said:
I would simply pick out a pinch and throw it in the trash can until the desire amount was reached. ... When I put the pan on the lab scale it was WAAAAY off.
Click to expand...

High, low or some of both?
 
Hi Keith. Hope things are going good for you. The scale on the Chargemaster read 34.9 - I pinched out some then the scale went to 34.8. I then took the pan and placed it in the lab scale. That reading was much lower than the other values. I do not remember what it was - but it was off far enough for me to take notice. As in "Holy S#$t. Look at that."

I'm not sure what ANOVA test is - I will look it up. Thanks for doing that. Again, I realize it was a super small test, but it still was some sort of test with some "repeatable" data.

This might be another case of "won't hurt might help" especially, if all I have to do is add more powder.
 
in the world of pumping things,,,water for instance, the flooded intake of the pump provides a constant supply of fluid....the amount of supply is refered to as net positive suction head......npsh
without suffeciant npsh.output of the piump will vary...some decrease some slugs of air...etc.

with a powder measure, we have a resivoir that provides a npsh to the output,,,,either a charge master or a hand operated measure.

the height of the powder in the resivoir is signficant......a baffle minimizes the influence of the height of the powder column.


some measures are influenced more by the height of the powder than others, powder type is another influence........

one must test each type of powder..not just assume that 4895 will meter the same as 8208....


mike in co
 
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I can certainly understand why/how the head of powder in a measure hopper can cause variations in the thrown charge assuming that there's a baffle in place and where the baffle is placed in the hopper. That still doesn't explain to me what the level of powder in a Chargemaster or other similar powder dispensing device has to do with the weight of powder dispensed.

I do know that makers of electronic lab scales want them to be powered up for a period of time (30 to 60 minutes) before they're used, and preferably left on at all times. I try to do that with my Chargemaster since the amount of power used isn't much, although I'm sure the über greens would have a fit.

One thing I've noticed with my Chargemaster is that when throwing charges for small capacity cases like the .223, .22 BR, or similar produces very infrequent over-charges. However when loading for an '06 with 4895 there are over-charges maybe once every 15 or 20 charges. The dispensing speed is what it came from the box with since I've got plenty of time.

Another thing I pay attention to is what readout shows when the pan is removed from the pan holder. If the readout varies ±0.1 the charge will be off ±0.1 gr according to my set of check weights. A set of check weights is valuable to have and to use. Not that expensive either.
 
Jason,
ANOVA = analysis of variance. I used StatPlus which is an extension of Excel.

There is video of the jamming phenomenon that can occur in granular flows at http://www.youtube.com/watch?v=lWSJwZhqoQw

Here is a book on granular flows:
http://books.google.com/books?id=RwAcJ0uw1EQC&pg=PA15&lpg=PA15&dq#v=onepage&q&f=false

This book mentions that granular flow rate becomes independent of the height of the column of granules when the height is above a certain threshold, and mentions sand in an hourglass as an example. Could be that filling the hopper with powder does the same thing.

Keith
 
Baffle templates

Apollo said:
My Chargemaster did not come with a "baffle"(sp). I notice on most throwers they have one. Can't be that hard to make.... That might do the same thing in a Chargemaster as it does on a thrower. Anybody here from RCBS? Am I even close to being on the right track?

Stanley
Click to expand...

Stanley,

I picked up a PDF template on baffle manufacturing:
Here it is.

I apologize for not being able to recall who is the original owner of the file, but I would like to thank him for it.

Cheers,

Phil aka tazzman
 

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  • powder_baffle_instructions_and_templates.pdf
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Phil.
Thanks for that information. I'm going to make one and try it - won't hurt anything. Our school's shop teacher also appreciates the info. Thank you.

No where in my posts have I wrote that having an ES of .08 will show up better on paper than an ES of .17. But, if one can make 'better' ammo - why would he not? Especially when all it entails is adding more powder to the hopper.
 
francis,
how much does it dump when there is no powder in the hopper ??
how much does it dump when the hopper is full of 4895 ?
how much does it add when the hopper is full of 8208 ?
it is influenced by the HEAD of powder behind the trickler....

mike in co

FBecigneul said:
Let me jump in here before the guys that don't know do.
We don't.
The chargemaster dumps when the scale tells it to.
It stops when the scale tells it to.
But, baffles look nice.
Click to expand...
 
On the last cycle, the Chargemaster rotates the trickler tube about a quarter turn at a time. How full the tube is determines how much powder is dumped during that quarter turn. If the scales says 34.7 when the target is 34.8, the tube turns a quarter turn, and however much powder is in the end of the tube comes out. That could be one kernel or a 0.3 grain clump. Not saying it does because I don't know, but the height of powder in the hopper could effect how full the tube is. The book I linked says the force below a column of granular material becomes independent of height above a certain height. This agrees with Jason's observations.

Cheers,
Keith
 
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