Weight Drift on Digital Scales
Electronic Scales can be a blessing. They are fast and easy to use (for the most part). But there is a potentially dangerous side as well. Here is a real-world example of problems you can encounter with common reloading scales.
I recently received a new box of Berger 95gr VLD bullets to test. These proved to be exceptionally uniform in base to ogive measurement so I decided to weigh them as well. I fired up my PACT electronic scale, letting it warm up for a full hour. Then I calibrated the unit using the check weights provided by PACT. I had a steady zero, the red cup tared (zeroed) correctly–everything looked good. I then started weighing the 95 VLDs, placing each bullet individually in a loading tray so I could repeat the measurements in order. After about 20 rounds I was interrupted by a phone call. I noted the weight (95.0 grains), wrote that down in my log book, removed the bullet, and took the call.
40 minutes later I returned to the loading room and re-weighed the SAME bullet. This time it registered 95.3 grains. Hmmm, I thought, that doesn’t seem right. Then I re-weighed each of the last five bullets (which were in order in the loading tray). Each one measured 0.3 grains higher than originally. I use the zero reset function to re-tare. Same results–0.3 grains high. Next I removed the red cup, re-zeroed and re-weighed without the cup. The bullets were still reading 0.3 grains high. Somehow the scale had lost its calibration.
Accordingly, I recalibrated the scale twice and re-weighed the bullets a third time. This time, following recalibration, they mostly measured the same as the first time, but a few registered 0.1 grain higher.
It was clear from this exercise that the scale had drifted 0.3 grains in a relatively short period of time. Even after the scale was recalibrated, some of the measurements were slightly different. This is cause for concern, obviously, if you are weighing powders. With small cases such as the 6PPC and 6BR, 0.3 grains will make a big difference in pressure. If you think you are loading 30.5 grains of Varget when in fact you are actually loading 30.8 grains, you’re in trouble.
What can one do to avoid this problem? First, allow a long warm-up time for the scale–3 hours or more. Second, recalibrate the scale before each loading session. Third, keep a check-weight handy and use that frequently to see if your scale is drifting. Fourth, there is some evidence that running the scale off a “line conditioner” that provides regulated voltage can help. This PACT unit did not have a line conditioner in place during our tests. Lastly, the “ultimate solution” is upgrading your scale. A higher-grade scale, such as the $275.00 Denver Instrument MXX-123, shown below, is much less likely to experience the problems of inconsistent read-outs and drifting zeros.
Denver Instrument MXX-123:
Amen! I’ve had the same experience with 2 other brands.
I have a Denver MXX-123 and it too drifts during weight measurements. I think that these electronics scales are all very sensitive to temperature. I use a balance beam for powder dribbling.
Editor: Steve, the unit Danny Reever tested for us did not exhibit that fault. Also the higher-end Denver Instrument tested by James Phillips was very reliable. But, yes these units are sensitive to air conditioning and very slight drafts. With you MXX-123 try putting it in a box to lessen the effects of moving air on the scale.
Scales are driving me crazy. Bought an electronic and found out I needed to plug it in and turn it on in the morning if I want to use it at night.Same deal with drifting, I have to continually re-zero. Had two balance scales which were a little old and decided to buy a new one. This started me playing with 4 scales and none read the same weight using a “53” grain bullet. Decided to use the new scale and was zeroing it last night and after zeroing, I pulled the pan and just set it back on the tray. Doggone, it’s off about a 1/10th and a half (line and a half).Finally get everything repeating and during the whole loading session was wondering if my charge was actually where I wanted it.
Hi, I do not think that air currents are the problem since I can fan the scale and see minimal effect on the reading. I can leave the scale on for the whole day and see it drift as the day goes on. Out in the Northwest most houses/apartments do not have air conditioning so we are at the mercy of mother nature as far as indoor temps.
You mentioned a “line conditioner”.Are you talking about a surge protector? Or is it one of the battery back-up systems?
While in Lowe’s I saw a surge strip that had ” computer clean power” on it. Is this the one you are talking about? I’m trying to see if something will help my Pact. Don’t have a lot of problems. But if something will help I’ll install it.
Love the helpfull hint articles.
Thank you.
Editor: I can’t say what the Lowe’s product does. A normal surge protector simply protects against extreme voltage spikes–sort of like a circuit breaker. However, it will still allow swings of voltage to get through. We’ve seen voltage (at the wall socket) swing between 80 and 145 volts. This was causing a computer battery pack (UPS) to constantly go off. A true “line conditioner” takes the voltage from the wall socket, analyzes it, and boosts or reduces voltage as necessary to deliver constant 110-120 AC through to the appliance. Some of the inexpensive UPS (uninterruptible power supplies) condition the voltage–others do not. You need to be pretty careful when you buy.
I just came across your blog about digital scales wanted to drop you a note telling you how impressed I was with the information you have posted here. I also have a web site & blog about digital scales so I know what I’m talking about when I say your site is top-notch! Keep up the great work, you are providing a great resource on the Internet here!
I bought the first MXX-123. It went “OL” second time I powered it on and put on the included check weight. It hung on “OL” no matter what. It could have been static charge killing it. Called DI (excellent people)and got a replacement without hassle. The second MXX-123 would stay zero after warm-up, but if you left the load on, it would drift up by itself at a rate of .02 grain a minute. I left the check weight on for a few hours to see how much it would drift upward – I got about .4 grain. It also wouldn’t re-zero after drifting upward. The drifted amount would become residue reading after I removed the load, and added on all subsequent weighing. I don’t have such problem with a PACT, but it read down only to .1 grain so it might just not be sensitive enough to show. I don’t have enough experience with other scales to know if that was a common “handicap” for electronic scale, but it make me question all those “reviews” for this particular products. I just expect a scale in that price range would not keep changing its mind. Am I expecting too much?
You bet the electronic scales are SENSITIVE. As one of the other comments stated – check, recheck , recheck and calibrate frequently. I rezero after every 5 rounds, use
cal. wieght every 10th round . Calibrate before beginning loading – leave the unit turned ON for weeks at a time – it will not hurt it.
My brother had a hell of a problem last year with a electronic scale going nuts on him – he was shooting 10’s and X’ss at 1000 yds then would have a shot go way off to a 7 or called miss.. He went home that night and reloaded a buncha ammo with a balance beam , came back Sunday and was shooting 10’s amd X’sss again.
YOU NEED A LINE -CONDITIONER – voltage varies continually coming into your house so you must maintain a constant incoming voltage for your unit otherwise what you see is the result of this variance.
Contact a good electrical or industrial supply house for a line-conditioner . Keep air movement away from the unit all possible…. oh yeah .. GOOD LUCK !
I had an issue with a drifting zero on my PACT, which made it unusable. It was happening at my house, but not at other locations, such as my office. The fix for my issue was a ferrous noise filter on the power supply cord . It is basically a hinged barrel shaped plastic tube that contains two magnets. Near the scal end of the cord, lay the cord into the slot, wrap it back through, then close the filter around the cord. Before installing, mine would drift off as much as 2.9 grains, which was being caused by some type of environmental “noise”. It is absolutely stable now. You’ll see a lot of these type filters on the cords for computer acessories. Yo may have to experiment to find one that works for you, some have different magnets that have different filtering abilities. Cost about $3. I purchased mine at Randolph and Rice Industrial Electronics in Nashville, TN item# SF.065 Hope this helps, it did for me.
Reading the comments here, I’m thinking it is a fact of life of an electronic scale. Many of you are talking about higher end expensive scales. I have a cheap digital that came with my “kit”. It does exactly the same. And as for line conditioners, mine operates off batteries. No cleaner powder than that.
Temperature,wind,and using cal weights that have been repeatedly handled without a clean white glove will all affect the weight reading to a certain degree.
Also binding will cause a reading to be out. And be careful to never exceed the scales weight limit as this can damage the loadcell permanently and cause drifting
You mentioned that you recalibrated the scale twice. It sounds like this would be a great thing to do when weighing anything! It is especially important when weighing really heavy things, like trucks or hardware.
Thanks for the tip to give certain scales a long warm-up time. I’d hate to start using it only for the scale to drift. I’d rather be safe than sorry when it comes to weighing things.