First off, I like this machine. I find it drops accurate loads. I am aware there is a static issue with these machines that can effect weight, so I wipe the plastic down with a dryer sheet. Usually solves the problem.

Last time I used it, I noticed the weight would indicate .5 to .9 grains higher after I opened the plastic shield after the load was dispensed. Close the shield, the weight goes back down to what was dispensed. I double checked the dispensed weight with a balance beam scale. Spot on. It would dispense 70 gr. I open the hood it reads anywhere from 70.3 to 70.9. Beam says 70 exactly.

1. Yes, I checked to see that there was no draft. Turned heater off.
2. Wiped down the cover and most of the dispenser with the dryer sheet.
3. Checked to see if there was any electrical interference close by. Magnets, wires, etc.
4. Turned off machine, restart, calibrate. Same issue.

So ... what gives?

I don't have the RCBS

I have the Hornady.

I don't use the shield.

I have RCBS and only use the shield for storing it between reloading sessions.

Barstooler

You might wash the shield in Dawn.
That is supposed to help with static issues.
I think I would try to set up a small earth ground mat for your measure and then ground the shield and the components the shield touches.

I have a Dillon scale. It has a draft shield with very small metal ribs to ground out the shield when it is down on the scale. In turn the scale has a small moat like channel with a metal ring in the bottom to complete the connection. It would probably all work better if my setup was connected to earth ground to bleed off any static.

Like others, I take off the shield when measuring different loads. I use the Charge Master to set up the powder drop on the Hornady Lnl, then verify on an ancient RCBS Balance Beam. I will have to check some loads with the shield on and off and see if there is a difference as you have observed. As a side, I always let the Charge Master "warm up" for an hour or so before I start measuring my loads.

I just turn it on,remove the shield and calibrate and zero it.Then I load.Mine is not fussy about air or temperature changes that I hear about.

Let it sit for a period where you are going to be loading so that its temperature stabilizes to the loading area temp. You probably did that , It may help for it to be on while that occurs,

Any of those scales can be sensitive to electrical interference from very close fluorescent lights. I have fluorescent ceiling lights overhead in the shop and have not seen any induced errors in mine. But close proximity could possibly create an effect.

The only thing I have to do with my Hornady unit is set the slow down to .2 or it will overthrow in fast speed

I have probably run 700 loads through this unit. It's been pretty consistent. I'll try a ground, I'll try washing it, I'll try to leave it on for a while. Good ideas. It's inside the house, so no temperature issues.

The issue is that the charge reads higher with the shield off, but not a consistent amount, this is with the same load in place! Open and close the shield a few times and you can get a swing of .3 to .9 difference. It's accurate with the shield in place (checked on the beam). So I'm hesitant to remove the shield. I like the draft protection the shield offers.

I'm working up some 7mag loads so I'll try it again in a few weeks see if any of this helps.

Thanks.

quote:

Originally posted by Wendell Reich:
First off, I like this machine. I find it drops accurate loads. I am aware there is a static issue with these machines that can effect weight, so I wipe the plastic down with a dryer sheet. Usually solves the problem.

Last time I used it, I noticed the weight would indicate .5 to .9 grains higher after I opened the plastic shield after the load was dispensed. Close the shield, the weight goes back down to what was dispensed. I double checked the dispensed weight with a balance beam scale. Spot on. It would dispense 70 gr. I open the hood it reads anywhere from 70.3 to 70.9. Beam says 70 exactly.

1. Yes, I checked to see that there was no draft. Turned heater off.
2. Wiped down the cover and most of the dispenser with the dryer sheet.
3. Checked to see if there was any electrical interference close by. Magnets, wires, etc.
4. Turned off machine, restart, calibrate. Same issue.

So ... what gives?

The first time I used my Chargemaster I noticed it did the same thing. I'm not sure I even know where the cover is anymore.

I think when you close the shield you compress the air onto the pan. The more you compress it the more it will weigh, so if you slam the shield shut fast it will weigh more as it closes before the air escapes around the sides. You can try that and confirm compared to if you close the shield really slowly.

I noticed a lot of variation in charge weights when I first got my Chargemaster. A friend pointed out that I'm located way out on the end of the electrical distribution line in our area so I used my Multimeter and checked my house voltage. It varied constantly from 111 VAC to 119 VAC and it was never stable for more than 2 seconds.

I found an old UPS (with battery backup), plugged it into the wall outlet and then plugged my Chargemaster in to it. It now has a constant 115 VAC and the Chargemaster is 100 times more accurate.

quote:

Originally posted by Fjold:
I noticed a lot of variation in charge weights when I first got my Chargemaster. A friend pointed out that I'm located way out on the end of the electrical distribution line in our area so I used my Multimeter and checked my house voltage. It varied constantly from 111 VAC to 119 VAC and it was never stable for more than 2 seconds.

I found an old UPS (with battery backup), plugged it into the wall outlet and then plugged my Chargemaster in to it. It now has a constant 115 VAC and the Chargemaster is 100 times more accurate.

Bingo ! !
"dirty" power can really mess with electronics.
Great solution Fjold.

muck

quote:

Originally posted by Wendell Reich:
I have probably run 700 loads through this unit. It's been pretty consistent. I'll try a ground, I'll try washing it, I'll try to leave it on for a while. Good ideas. It's inside the house, so no temperature issues.

The issue is that the charge reads higher with the shield off, but not a consistent amount, this is with the same load in place! Open and close the shield a few times and you can get a swing of .3 to .9 difference. It's accurate with the shield in place (checked on the beam). So I'm hesitant to remove the shield. I like the draft protection the shield offers.

I'm working up some 7mag loads so I'll try it again in a few weeks see if any of this helps.

Thanks.

Have you by chance noticed the situation is worse now that it's winter and you're possibly running the heat in the house. Winter time with hot dry air coming out of the vents tends to be worse for static electricity in the house.

Just wondering out loud, but you may also have more charge built up on your body, specifically hands, and when the shield is opened it has more effect, maybe?. Are you standing on carpet where you load? That would make things worse.

I have noticed the same issue with mine, but to a much lesser extent. Mine will frequently jump by 0.1gr when I open the shield. But I load in my garage where it's not heated and I'm standing on concrete.

I too thought about the fluctuations in AC voltage. When I set mine up I checked my AC and it was rock solid at 122 VAC. I did still use a UPS though, just to be sure.

I also bought some grounding clamps, some anti static gloves and even a ankle or wrist ground set. But I have never had to use them.

I have both the 750 as a quick scale and the 1500 . Both will wander some at times, but the more stable the temperature, the less variation. It is just a fact of the small strain type sensors. A zero or two brings it back in line generally.

If you do go up to a lab quality scale that measures accurately in 0.01 grains , they are affected by everything including fluorescents lights and temperature, but they have a better shield. Youo can track the error with temp etc . Good stuff, but they can be a pain.

If none of that works, I have heard before that RCBS is at least pretty good about checking these and repairing them even when they are beyond their warranty period as stated. I saved my box for just such an occurrence, but it hasn't happened yet, knock on wood.

I never use the shield on mine. Been using it now since they first came out maybe 8 years ago? Works great. But I always drop the charge on an acculab scale right after and then I make the slight adjustment if needed on it.

I tried mine with and without the shield last night, and it worked perfectly either way.

quote:

Originally posted by Terry Blauwkamp:
I tried mine with and without the shield last night, and it worked perfectly either way.

+1

After reading Wendall's post...I tried it several days different ways...never any change. And...I have done nary a thing to combat static electricity with mine and just plug it into a plain ole wall socket.

had a similar problem and was asked to re-calibrate, weight a few loads and then repeat to demonstrate uniformity.
Turned out that one of the feet on the unit was not making full contact with the table and that made the difference. go figure.

I had a similar problem with mine and learned that the balance was not perfectly level. After leveling and ensuring all feet where contacting the table, my problems went away.

Graybird reminded me....

I three point leveled mine

I too have a change in the charge weight when I open the cover..It maybe due to air flow or something like that. But I still get great groups with the dropped charges.

Mine has thrown heavy very consistently. Did all the setup stuff with the checkweights, two different sets, did all the levelling tricks, and use some Bounce in the hopper. If I set it for 50 gr, my two other scales, set up the same way, one beam, one old Lyman 1000 electronic, both say 50.1gr.
I can only attribute it, to what the scale sensitivity setting, tells the readout to kick over digits at. At least, the beam scale seems to be pointing me in that direction, due to the needle reading on it, showing say approx 50.05, or less in some cases. Tried it with a 1/2hr warmup, , 1 hr warmup and a no warmup. tried it with checkweight calibration, and using it without bothering with that procedure, still does it.
However, it is consistent enough, that I just set it at .1 under what I want and fly at 'er.
And keep an eye on the pan/no pan readings, to watch for drift. Only time I close the cover is when I am done.

Interestingly...mine does fluctuate .1 gr with the pan/no-pan reading from time to time. 70% of the time I get a -157.2 gr reading when pan is off. 30% of the time I get a -157.3 reading when the pan is off. But...it always goes back to zero when I replace the pan.