Digital balances

[mooncoon]

I finally broke down and bought a digital balance a couple of days ago. One of the uses I had for it was to trickle charge powder charges. Much to my surprise, I cannot trickle charge with it. After warming up and calibrating it is in agreement with my RCBS beam balance and adding and removing the same object repeatedly it gives the same weight. BUT if I start with an empty pan and trickle about .1 grains of powder on, it flickers and returns to zero. I can add a total of 5 grains or more in steps of .1 grains or so, and the balance still reads zero. If I dump the powder out and put the aluminum dish back on the scale, it reads accurately the amount that I dumped out. I also tried taking the aluminum dish off the balance and adding .1 grain more powder and weighing the result --- it did not.
I took the balance back to Caballa's and a customer there said he had similar and worse problems with a different brand of digital scale and which turned out to be caused by the overhead florescent lights. I tried turning out the lights and using natural daylight only; same problem so it was not the florescent lights in my case. Also tried a second digital scale, same make and model (Cabella's XT 1500), while in the store and same problem

Question then is; do most digital scales have the same problem or is there a way of combating the problem? It cannot be a problem with the more expensive models which dispense powder charges because they throw about 95% of the powder in one dump then trickle more to the exact weight

cheers mooncoon

 

[silverfoxdj]

I've struggled with digital scales as well the latest is leaving it on for hours before using it and adding a line cord filter ..to eliminate interference (the court is still out) on these..

 

[stubblejumper]

I have not experienced that issue with my digital scales. I have had no issues at all with either of mine.

 

[calgarycanada]

Mooncoon it's perfectly normal for digital scales. Here's some info from Myweighscale website

"Adding light loads or “dribbling” can cause display problems. Digital scales have an auto-zero function. The way this normally works is that if an item is placed on the tray that weighs less than half of one division, the scale will zero that out and maintain a stable display (this is done so that the scale can maintain a stable weight reading and adjust for vibrations or air movement). In layman’s terms that means if you purchased a scale that reads in 1 gram increments, and you place a 0.3g item on the tray, the display will not change. Then if you place another 0.3g item on the tray, the display still won’t change. Therefore it’s possible to very slowly add weight to the tray and have the display not change at all. That is why NIST recommends that you purchase a scale that has a display resolution of at least 1/2 of the smallest item you intend to weigh (including ‘dribbling’ or adding items). So if you intend to weigh buttons, and each button weighs 1 gram, then you should purchase a scale that reads to 0.5 grams.

Therefore, it is recommended that you do not place items that are less than the display resolution on the tray during the weighing process."

 

[islandkent]

^^^^ Thank you for that explanation sir.

 

[Bassmaster]

^^^^ Thank you for that explanation sir.

Yes, that does certainly explain a few things I've been puzzling over

 

[calgarycanada]

^^^^ Thank you for that explanation sir.

You are welcome buddy.

 

[kayaker1]

I am very happy with my RCBS 1500 but don't trickle from zero. Just the 'regular' technique of dump the majority of the charge and trickle the finish.

 

[fingers284]

I haven't tried what Moon is talking about with my RCBS digital, always dump a close to full charge and then trickle, but my Lyman dispenser starts at 0 every load and measures/progresses at a fast trickle until close to finish when it slows to a crawl and slow trickles the last tenth or two.

 

[DMT]

I will turn my mine on and leave it for up to a day. If I didn't, it wouldn't always returns to zero, and could be out by 0.2 grns after loading the round. By leaving it warmed up, it nearly always returns to zero. My procedure is to dump approximately the charge weight, but using either a loading spoon or the powder thrower, and then just trickle in the last few grains.
One other technique is to slow down when it is 0.1 grain below the required load, and then only just put in the last couple of powder grains that the weight indicator just turns over to the required charge and then stop. If the scale weighs to 0.01 grain this wouldn't be an issue, but as mine only weighs to 0.1 grain, this technique is to try to get it consistent from one charge to another.

 

[Chinbullco]

Have drift in all digital scales I have. I picked up on this by weighing charges on an old 10-10 RCBS scale. So I have returned the digital scales to their original packaging and placed them in storage. Have an RCBS Chargemaster that I use for load development. When a load is found use a Harrell's measure and that trusted 10-10 scale. If I had to wait a day for a scale to settle down I would kick it though a wall.