PACT digital scale shenanigans

[callgood]

In another post I mentioned weighing some Hornady 75 grain HPBTs on my digital scale. It is set up in my computer room on a TV type table, which is as level as I can get it.

Two nights ago I weighed 100 and segregated them by weight.
Last night I recalibrated the scale and started to weigh another 100 and noticed the size of the different weight piles wasn't following the previous night. So I decided to re-weigh the first nights bullets.

The 75.2 grains were now 75. The 75.1s were 74.9. This may or may not be a big deal, but I'm going to try this with powder, especially in the 25 grain range I'm using with Varget. I'd be more concerned with changes in group in that situation, and I'm surely going to try it with my 9mm load weights. I don't generally load to the max but this ain't kosher!

I have a 505 for backup. I'll also see if I can detect a change on it from 75.0 to 75.2.

Thanks for any suggestions,
Callgood

 

[WayneConrad]

Electronic scales like being left on. If you have an a/c adapter for it, just leave it on. If it is battery powered, leave it on for some time -- say 15 minutes -- before you calibrate and use it.

Some electronic scales are sensitive to the position of the load on the platen. Make sure your bullets are in the same place every time.

Ceiling fans and air conditioning ducts, or vibrations from a light table can cause problems. These things are pretty sensitive.

It's worth nothing that the error you are seeing is less than 0.3%. That's very good. I can't imagine a cartridge where 0.3% error in the weight of the powder will be at all noticable.

Edited to add: With that last statement, I think I stepped out of what I know and into what I think. I suppose a tenth of a grain could make a difference. I really don't know.

 

[EddieCoyle]

Wayne speaks the truth. Leave it on. I have a PACT digital scale and here's some of the things I've noticed:

If you leave it on for a long time, you'll see the weight reading (with nothing in the platen) change, slowly over time. Every once in a while, press the "Tare" button to rezero the scale. Eventually the drift stops. This can take a day. This is where you want to be when you are using the scale. This is also why you have to leave it on all the time.

I haven't seen any changes caused by wind currents or by the scale being out of level (I'm sure that mine isn't perfectly level. I've never even checked it). However, I have seen other things affect the readings. I reload in the basement of my home. When the dehumidifier kicks on, the readings begin to change. A similar thing happens if someone is running a vacuum cleaner nearby, or if the scale is near my computer or monitor. These things are caused by electrical noise - both EMI and RF.

 

[callgood]

Wayne speaks the truth. Leave it on. I have a PACT digital scale and here's some of the things I've noticed:

If you leave it on for a long time, you'll see the weight reading (with nothing in the platen) change, slowly over time. Every once in a while, press the "Tare" button to rezero the scale. Eventually the drift stops. This can take a day. This is where you want to be when you are using the scale. This is also why you have to leave it on all the time.

I haven't seen any changes caused by wind currents or by the scale being out of level (I'm sure that mine isn't perfectly level. I've never even checked it). However, I have seen other things affect the readings. I reload in the basement of my home. When the dehumidifier kicks on, the readings begin to change. A similar thing happens if someone is running a vacuum cleaner nearby, or if the scale is near my computer or monitor. These things are caused by electrical noise - both EMI and RF.

Well, I'll have to move the location. I am set up 3' away from my computer. Those monitors can put off quite a field. It's also plugged into the power strip with the computer. This is a good room. The kitchen is out- refrigerator drives it bonkers. I'll set it up in #1 daughters old room and leave it on. I'd like to put some clean power on it and see if that helped. My APC needs a new battery. I'll try these tips. Thanks, guys.

UPDATE-
I set it up last night and let it sit there. This a.m. I calibrated it and weighed a bullet from the 75 grain bag- 75 grains. I'll check it this evening and see if it has "drifted" off "0.00."

 

[nothinbutguns]

Call me old fashioned

Bought a used RCBS manual scale 25 years ago. Still using it and wouldnt have it any other way. No batteries, no power, no electronics and no problems. Weighing bullets? Spend less time weighing and more time shooting.