does your beam scale do this ??

[mike in co]

was doing some loading and notice that when trickling in the last tenth or so that trickled "zero" was not a zero if i touched the beam and let it setlle.

as in a tenth over weight....

i had never noticed this before...and i dont use it as much since a got my mx-123 lab scale(electronic).

so it would seem some of my scaled charges were propably not so precise.

anyone else see this or knew it from day one and never did it this way ?


inquiring minds want to know.

mike in co

[Bent Ramrod]

Mike,

There's always a little hysteresis in beam balances. (This is the ability to get two different weights depending on whether you start from underneath and add more or from above and take some out.) Even the old two-pan analytical balances had enough hysteresis so you had to weigh by keeping the beam swinging and noting that it swung the same deflection each way when the weight was exact.

With a single pan beam balance, the solution is to always start low and trickle up. If you run over, take out enough powder so the beam is low again and retrickle. If you do this, the weights will be reproducible. (If the balance is calibrated with known weights, it will be accurate as well.) If you touch the beam, touch it so it pushes in the "down" direction and comes gradually back up, rather than going high and coming back down. To the greatest extent possible, avoid touching the beam with your fingers; use a pencil to keep skin oils from building up on the beam.

[shotman]

Also dust in the pivot will cause that.

[1hole]

Shotman is right, it's likely friction and dust in the bearings can cause it. Beam friction can also occur if we allow the beam to shift forward or backward so a pivot bar end can rub against the clip holding the pivot bearings. Clean you bearings (a wet tooth pick works good) and center the beam in the bearings and your reluctance to follow the charge will likely dissappear.

Hysteresis is a reluctance to change states, not simple friction that reduces a devices ability to follow a change.

[crabo]

[QUOTE=

Hysteresis is a reluctance to change states, not simple friction that reduces a devices ability to follow a change.[/QUOTE]

Sounds like a prevalant human condition. I just didn't know the 25 cent word for it.

[1hole]

You got that RIGHT! I have quite a few friends whose families have voted a single party since FDR, they hate what that party has become but can't bring themselves to change adn go against tradition! But I don't call it hysteresis, it call it stooopid!

[be603]

So does political hysteresis leads to hysterical hatred of handguns?

Fancy name for a sort of dead zone. I use a home thermostat as an example of hysteresis when explaining to my kids. First came across the term "input hysteresis" when I was Jr Quality Engineer. One of my early tasks was doing switching pwr supply acceptance testing. We had a difficult spec that their ability to recover/restart after a line drop (e.g. cold morning starts on a vehicle). The supply would drop out under something like 9.8 VDC but the supply would not restart until the input recovered to 10.4 VDC.
back on topic, thanks for the discussion. Now I'm going to have to look at my methods with my old Redding single beam and see if I can improve my repeatability.

[dubber123]

Every beam scale I have ever used does this to some degree or another. I noticed it a long time ago, and developed the habit of tapping the scale when the beam reached just under level. With a little practice, I can usually get it to level out right at the correct weight. If I don't tap, I will get the 1/10th weight variation you noticed.

[stocker]

I learned that the beam may bind if allowed to come to a stop and consequently give a false reading. I have several scales and they will all show this trait occasionally if allowed. Some sources recommend reading the scale while it is still swinging- more or less equal amounts of deviation above and below zero and that is what I have done for 50 years.

[EOD3]

Another thing worth checking is side to side level, or front to back, whichever you prefer.

[Potsy]

Whew!
I thought it was just my scale doing screwy stuff.
I use my digital anymore loading pistol shells, but still use my RCBS (ohaus) to load rifle shells where a tenth usually isn't the end of the world.
I was bright enough to figure out one day that a running ceiling fan over your loading bench can play all kinds of merry havoc with a beam scale.

[Capn Jack]

After cleaning my old RCBS I found the oil damper paddle had gotten bent :roll: and was rubbing the side of the oil reservor.[smilie=1:

[geargnasher]

As Bent Ramrod and Stocker both said, read the scales while still swinging and gauge equidistant from center. One method I use is place the pan and charge, then peg the beam up and let it fall (with a magnetically damped rcbs scales) so it encounters the same net friction each time before coming to a standstill (do this for consistency, not for finding exact initial charge weight).

Gear

[Echo]

What 1Hole said. Sounds like dirty pivots. They are usually made of agate, and very hard, but dust can settle in (why I like my 10-10 w/dust cover) and create friction that will act just as you describe.