Can barometric pressure affect my beam scale?

[wallenba]

I've spent the last couple of hours checking the accuracy of my Little Dandy rotors. After zeroing my RCBS 10-10 the first one a #3 checked perfect, five in a row. The #4 was a couple of tenths heavy, and seemed to get heavier every other throw. Then the #5 was a full grain over. I rechecked the zero and it was way off. I began checking the zero each time I changed a rotor, and it was always needing re-zeroing. All other variables are the same, and the tubes and rotors are well seasoned. What's happening here?:veryconfu

[oneokie]

Are the pivot points clean?

[wallenba]

Are the pivot points clean?

Yep, they are, but I'm going to go over everything again in the morning. I'm a little frustrated and a little tired right about now, and I don't do my best work like this. Possibly you are right, a grain of powder might have gotten in there. I keep this scale under glass too.

[Bulltipper]

Barometric pressure should not affect your beam scale. humidity could and friction could, FOD could, but I can't see ambient pressure causing heartache...

[462]

FOD, now there's a term I hadn't thought about in a long time.

[wallenba]

FOD, now there's a term I hadn't thought about in a long time.

Me neither, but I'll do a walk down.:bigsmyl2:

[waksupi]

What is your local weather and humidity like? Powder can attract moisture.

[noylj]

As long as the pressure on one side of the beam is the same as on the other side, there can be no effect.

[wallenba]

What is your local weather and humidity like? Powder can attract moisture.

Could be humidity, but with the small throws I was tossing (3-4 grains), and the density of Win 231 it would take a lot. Also the house has central air and is pretty stable inside. I cleaned the pivots this morning and wiped down the damping magnets. I also noticed the damping plate was favoring one side of the slot more than the other. I bent the beam slightly to center it better. Later I'll give it another try.

[wallenba]

As long as the pressure on one side of the beam is the same as on the other side, there can be no effect.

Must be on the right track noylj. I gently bent the beam to get the damping plate centered in the slot. After that the plate itself was a little crooked in the slot. I tweaked that until it was close as possible to being straight and centered. Results are a lot more uniform now and staying zeroed. Question is, why did this happen now? This is the first time I have used it to measure small charges. I was using the Chargemaster for all my loading, but recently decided that a rotor dispenser would be quicker and easier to set up. 380's and 9mm go faster at the range than the other stuff, and aren't as accurate anyway.

[MtGun44]

No, it can't.

[wallenba]

No, it can't.

It's always the simple stuff that I don't get Bill. Because of just that. "It can't be that easy"! LOL:wink:

[oldscool]

You should check to see if your knives are touching on one end or the other in the pivot rest.
When you zero, or move the beam balance or dial, it is easy to push the assembly so it is touching one of the ends. This will cause a slight drag, and throw your weights off a little, then after weighing a few, it may center itself and free up = thus the same thrown weight appears to weigh more than the initial ones. I should have a note pasted on mine to remind myself of this, as I often forget to check that at first after not using my scale for a while.
I am a firm believer in using check weights and checking periodically thru my load throwing also. I use a student milligram set along with my grain weights to get me closer to my tenth grain settings.
Good luck in finding your problem.

[Skipper]

Turn off any nearby florescent lights.

[wallenba]

[QUOTE=oldscool;1362026]You should check to see if your knives are touching on one end or the other in the pivot rest.

Well ya made me put my best specs on and take a close look at the knives. Here's what I see. The knife shaft is not square to the beam. That's why it needed bending. Also, the knife edges seem to be tilted backwards. I don't know what is normal for it, but I think a call to RCBS is waranted here. Here are some pics of both.
Keep clicking on it til you get the + & - signs for biggest pic.

[1hole]

"Can barometric pressure affect my beam scale?"

No. Nor can flouresent lights. But mechanical damage from rough handling sure can; that kind of treatment destroys digitals too.

[Skipper]

Speer:

"Keep powder scales at least three feet from fluorescent lights to prevent inaccurate readings."

This can effect magnetically dampened scales.

[1hole]

Speer may not be right.

As a retired electronics tech from the space and defense industry I do know a bit about the issue. First, it's not fluorescent 'lights' that are a problem, it's magnatism from the old type ballast units; few of those are still in use, very few in homes. Second, the beam itself in any scale will be made of a non-magnetic material. Last, the copper vane used to dampen the beam would hardly react to any stray tiny AC magentic fields that changes some 120 times a second.

It is true that cheap digital scales can be twitchy in strong electical fields but they aren't the issue here. And ALL reloading branded digital scales are cheap no matter their retail cost. "Good" digital scales start around a kilo-buck and even they need routine checks by a trained tech with test tools to keep them operating properly.

Or maybe Speer knows more. ??

[felix]

No Speer won't know more, but Mr. Blodgett will. I wrote the software, and designed the computer hardware, for operating his scales on top of MiraPak packaging machines. Next time you open a bag of FritoLay chips of any sort you can think of yours truly. ..... See www.theblodgettcompany.com

... felix

[EOD3]

No Speer won't know more, but Mr. Blodgett will. I wrote the software, and designed the computer hardware, for operating his scales on top of MiraPak packaging machines. Next time you open a bag of FritoLay chips of any sort you can think of yours truly. ..... See www.theblodgettcompany.com

... felix

SO!!! You're the RAT-B*****D responsible for the half empty bags. :kidding: :2 drunk buddies:

[oldscool]

Dutch,

You found your problem. What you are showing is not normal. All should be square and plumb. You do need to call, and probably send the whole thing in for a good going over. RCBS should take care of it for you under warranty.

[August]

As an old science teacher, I can tell you that beam scales do not work when used statically. The beam must be moving to measure something. The observer's job is to get his eye in the same position relative to the scale every time (I like to put my chin on the table), and to insure that the pointer is "bouncing" equally above and below the zero point during zeroing or when taking a measurement. Scale will not be consistent if it is not moving.

[mdi]

Thank you Felix. I love Fritos...

[felix]

Yeppers! However, the law says a case lot must be accurate as stated on the bags. So, just like cartridges, eh?
50 grains of powder loads MUST have 50 times 20 grains of powder for the BOX of 20 sold. That is under the weights and measures laws. Found out about that when doing the job. ... felix

[MtGun44]

The comments on keeping the scale moving for accuracy is right on. There is almost always
a bit of static friction that can hurt your accuracy. I touch the beam to make it move about
2-3 marks either side of the center to get a good reading. Keeping the knife edges smooth,
clean and sharp and the v-blocks (stone in many scales) clean will minimize static friction,
but cannot 100% eliminate it.

Bill

[wallenba]

I'm betting the moon can affect it over time. It pulls the tides up.
I watched a video on youtube last night. Polite South African gentleman gives some good tips here: http://www.youtube.com/watch?v=HOKJxe0FUTk

The bit about adjusting the weight of the pan holder was not in my instructions. It makes perfect sense.

[oldscool]

Did you send your scale in, or was it just a matter of not starting with a correct zero? Sounds odd that even starting with a zero that is off a few tenths, or even more, that it would grow with a substained weight.

[Sonnypie]

No, barometric pressure can't.
But watch out for fart dust. That gums up the works. :shock: :evil:
(Ask a silly question, get a silly answer.)

When my 5-0-5 acts up, I just puff it off gently with one of my shop blow guns (Compressed air).

[Char-Gar]

I had a magnetic dampened scale that drove me nuts for months. Just before I started to pitch it in the trash can, I did one long last look with a magnifier and strong light. I found a very small bit of steel that was causing all the problems. Where, it came from and how it got there, I have no idea. But, once removed the scales went back and behaved as they had for years.

[1bluehorse]

I have had to replace the poise jewels? on a 1010. They will wear over time. RCBS will send you replacements. Simple fix. Could be your problem.