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RCBS Chargemaster measurements "drift" over time?

Discussion in 'Ammunition & Reloading' started by skyfire1201, Jan 19, 2014.

  1. skyfire1201

    skyfire1201 Seattle Member

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    Hi everyone,

    To folks who own/use an RCBS chargemaster to load their ammo, I've got a question for you. I use the Chargemaster 1500 to measure a charge, which is pretty deadon. However if I don't take the pan with powder off the scale after the measurement completed, and just leave it on the scale, I've found that over the course of a few minutes, the measured weight will "drift" higher, sometimes by as much as 0.5gr. Keep in mind, this is without any powder trickling into the pan, and happens just by letting the pan with powder sitting on the scale.

    I calibrate the unit before each session, and make a few measurements on it to "stabilize" the unit before proceeding to work on real loads. So far I've tried to static electricity elimination, putting on the clear plastic draft protection cover, level the front and back, and nothing seems to work. I have my chargemaster plugged into a surge protector, and the problem still persists, frankly I'm out of ideas as to why this may happen, and is starting to worry about the accuracy of the unit.

    Anyone ran into similar issues?
     
  2. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    Assuming your anti-static treatment was effective, and you did warm the unit up for at least a half hour before use, you might want to get a line filter for your unit. --and/or-- If the unit is an older one that was actually manufactured by PACT, there is a software reset procedure you can enter from the keyboard that will fix the problem if, and only if, it is an internal programming glitch--not likely but it does happen. I had a similar problem with a PACT that was fixed by using that method.

    Before running out to buy a line filter (a surge protector is something else) you will want to see if the problem keeps happening if and when the scale is moved to a different circuit (not just a different outlet) or even a different location entirely--such as a friend's house, especially if the friend has a digital scale that works with no problems. You might want to read this: Line Noise Filter for Reloading Scales within AccurateShooter.com

    I keep my scale and dispenser on an anti static mat--cheap these days and can be ordered online-- and use a 65 pound pull rare earth magnet as a line filter. The magnets are cheap and online also.
     
    bcdon and (deleted member) like this.
  3. skyfire1201

    skyfire1201 Seattle Member

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    Thanks for the info sharing SinisterSouthpaw!

    Mine is recent manufacture, not sure what the older PACT re-labeled one looked like. I didn't know I had to warm up the unit for 30min before use :( Does it have to be running and dispensing all that time, or is plugged in, turned on OK? As far as anti-static goes, I have it situated on a large metal table, and regularly touch the powder pan and my hands to the table. Is that adequate? Also how can I tell if the issue is with static?

    I threw some more charges on it last night. Up on initial measurement things appear to be quite accurate. However after I threw 10+ charges, and goes back to measure the charges with the factory metal pan (I typically measure using the RCBS plastic pan with integrated funnel), the charges will come out reading .3gr higher than their original measurement. I think the results are the same using the plastic pan as well. Basically, upon re-measuring the unit always reports higher readings than when they were originally dispensed.

    Now you got me curious: the rare earth magnet you were talking about, are they the cylinder type which allows a cord to pass through that you see on older style VGA monitor cables? How does that work as a line filter? Could you point me to the link where you bought yours?
     
  4. My 3 sons

    My 3 sons Bonney Lake Active Member

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    I don't have the RCBS model but my auto disp will do the same thing at times. Sometimes the issue is static but I also was told that build up under the plate needs to be cleaned out with compressed air once in a while. When I've done both of these I have no further issues.

    In addition, does your scale sit on the same surface as your press? Isolating your scale eliminates vibrations that may throw it off as well.

    Best of luck.
     
  5. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    It's hard to see how powder could get under the plate on either of my scales; I think the RCBS set up is the same- after reading 3son's post I took the plate off both mine and looked--nice and clean--and its also hard to see how vibration can affect the scale when the dispenser is idle.


    I got my magnets from kjmagnetics.com for a different purpose, but after I bought a dehumidifier to use in my loading/gun room I had some problems with the scale drifting - some were related to the air currents set up by the fan in that unit and some were from noise on the line. I remembered reading the 6mmbr article and laid one of my KJ magnets on the power line about 4" from my scale and it fixed the remaining problem. I can't remember who I got the anti-static mat from, but I do remembered I googled the subject and was presented with about 20 choices of retailers.

    I imagine that RCBS will be less than helpful about identifying units that were made for them by a direct competitor--as in the die patents they leased from Lee. Still, If things have not changed in the last couple of years, if you want to have your RCBS scale repaired you must send it to PACT. Possibly your warranty info in the owner's manual might have some contact address, or you might ask RCBS cust. serv. or even PACT. Since most of the digital scales sold for our purposes and a lot of others are all built on the PACT patent, they are usually pretty busy and will probably be happy to tell you the secret reset code procedure if one exists for your scale and it is one of their designs.

    Also, everyone else with a digital scale/dispenser setup might want to keep in mind that while wiping out the powder reservoir with a dryer fabric softener sheet is a good idea, it does nothing to prevent the introduction of static electricity from other sources. The fabric softener sheet will help to control static and clumping/bridging of powder in the reservoir, but it does nothing to stop static from your body from affecting the innards of the scale when you touch it. If you are working on a carpeted area, you might want to use the anti-static mats and be sure you are wearing rubber soled shoes and sitting on an insulated chair. Most of those procedures are overkill, but sometimes static can be really nasty depending upon the climate and carpet fiber type. I decided to buy a mat after I was zapped by my cat while I was working with my first digital scale--the resulting errors from it put me in contact with PACT and the secret reset code and etc. Since I got the mat for the top of my bench I can drag my feet (in socks) across the carpet from the living room through the family room into the gun room and touch the screws on the light switch and make a big fat spark that hurts like sin on my finger. Doing the same thing and touching anything on the AS mat yields no spark and if I touch anything else conductive off the mat - also nothing --after I have discharged through the mat by touching it or things on it. Static is a problem only during certain times of the year here, but with the mat I don't have to worry about the time of year or how dry I made the place with my dehumidifier--only the cat has to look out for zaps!--he really hates that...........
     
    My 3 sons and (deleted member) like this.
  6. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    I should have said warmed up prior to any use............sorry.
     
  7. skyfire1201

    skyfire1201 Seattle Member

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    @ 3sons. Yes, my chargemaster is on the same surface as the press, though I never mode the press during the final phase of the dispensing. I'm very careful about powder getting on the plate or underneath, and always kept it clean (in fact I use tweezers to remove any grain I can find on any nearby surface).

    My reloading bench is in the garage, which is epoxy coated, and I've never had any static electricity shock problem around the house. Regardless, I'll try the antistatic mat routine. Which part of the dispenser can static electricity build up on? I wonder if I can just tie a piece of wire from the unit to the big metal desk it's sitting on and achieve the same grounding effect.

    @Sinister. As for magnets, I heard the magnetic field on the magnet can interfere with the accuracy of the unit. When you said placing the magnet solved your remaining problems, were you referring to the stability of measurement?

    And when you warm up the unit, do you just turn it on an let it sit for ~30min?

    thanks guys!
     
  8. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    My scale would drift enough for it to go into error mode any time I had the dehumidifier on while the scale was on. Part of that was the air currents produced and part was line noise on the AC circuit induced by the fan in the dehumidifier. Laying the magnet on the power line from the wall tranformer going into the scale fixed the rest of the drift problem for me. I placed the magnet about 4 inches from the scale. If I know I am loading powder today, I get the scale out in the morning, plug it in have breakfast, feed the livestock listen to the news and do everything I need to do to get ready to start loading. Once I have done all the case prep and primed the cases I calibrate the scale, then the dispenser and beging throwing charges.

    I store my dispenser with a dryer sheet stuffed into the reservoir this eliminates static in the dispenser. If you are working in a non-carpeted area it is less likely to be a static producing place than if working on carpet, still, static can be a problem and will most likely be introduced by you and your clothing if it happens at all--if you have never ever in the history of your garage noticed a little zap when touching metal or lightsitches, I think you might put the static mats and wires low on your fix it list. Try moving the scale into the back bedroom or any area far from the garage and definitely on a different ac circuit. and letting it idle for a while, weigh some cases and see if you get the drift in that location. If the drift goes away when the scale is relocated, you know you have a problem in the garage, either in the power, the air currents, or the old indian burial ground it was built over.:paranoid:
     
  9. skyfire1201

    skyfire1201 Seattle Member

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    Followup from this thread, I did a bunch of experiments with various things I can do to improve accuracy. I tried 1) warm up the unit; 2) use anti-static laundry sheets; 3) ground the unit; 4) level the unit some more (it's already on a fairly leveled table) by adjusting the rubber feet; The only thing left to try is using magnets on the power line (ordered), and putting the unit on a UPS. Warming up the unit definitely seemed to help, I threw 25x 10gr charges right after turning on the unit, compared to another string of charges after letting the unit sit for 1 hour. The accuracy, according to the scale itself, improved from an average deviation of 0.071 to 0.048. The best result was after I let the unit sit idle powered on for 3hrs+, then measured a string of 10x 17gr throws, of which there wasn't a single 0.1gr of variance, thus getting an average deviation of 0! I think I just got lucky on that string, 'cause I could never reproduce it since.

    Interestingly, letting the unit further sit powered on for 24hrs didn't make things any better. In fact, a string of 10.9gr throws widened the average deviation to 0.054. Although all this time, the charges were never more than 0.1gr (according to the built in scale when re-measured later on) different from the desired amount. I'll see what magnets can do to further reduce that, though it's already within RCBS's claimed accuracy standard. I guess I could just leave good enough alone, though I can't help but to try squeeze that last bit of possible accuracy out of this unit :D
     
  10. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    Trying for less than +/- .1 GR. tolerance is not only a waste of time but counterproductive. Not even the 1000 yard BR shooters worry about less than that..or snipers...........or varmint hunters...........etc.
     
    Spadkarma and (deleted member) like this.
  11. skyfire1201

    skyfire1201 Seattle Member

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    Can blame a guy for trying :)
     
  12. 10 Spot Terminator

    10 Spot Terminator Central Oregon Member

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    The warm up cycle seemed to be the culprit for me when I first started using my 750 several years ago after I eliminated the exsposre to flourescent lighting and not using it when the central heat/cooling fan was on . I beat the warm up cycle issue by never unplugging my charger and just letting the unit go to sleep . I have used my 750 for over 10 years and have grown tired of cross checking the weights against my 5-0-5 balance beam scale .

    10 Spot
     
  13. SinisterSouthpaw

    SinisterSouthpaw SW WA Active Member

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    But Sky--just think of all the other neat stuff you could be trying if not fooling with that dead end. You could be trying to find the perfect neck tension and compare the methods used to achieve it--outside turning versus reaming--and then seating depths can keep you busy for months and bullet meplat pointing vs, trimming and......
     
  14. skyfire1201

    skyfire1201 Seattle Member

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    OK, ok, point taken :D
     
  15. 44mag2ndamend

    44mag2ndamend Round the ole tree stump, Down by the crick Well-Known Member

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    Weird bubblegum happens with electricity. Voltage on household may or may not go up and down, I lost a labtop to having it plugged into and ungrounded circuit and I was using a surge protector.

    There is a variance specification with anything man has made.