POWDER SCALE PROBLEMS

15 April 2003, 08:29

Hey guys -

Do any of yous have trouble with your scale maintaining its zero?

I notice that many of the current models have eliminated the adjusting nuts on one end that you could use to "zero" your scale. NOW what the heck do you do if the zero is off? I'm finding some scales are off. Obviously, you can add a tiny bit of weight (pc. of paper, etc.) to one end of the scale to rezero, but that seems rather "cockamayme". What on earth are the scale makers thinking?

Also, do you think the magnetic damping is a help or hindrance to accuracy and sensitivity?

15 April 2003, 09:03

Leftoverdj

Look for an adjusting foot under the base of the scale.

Lacking even that, you can add sheets of paper under one end until the scale zeroes.

15 April 2003, 11:21

denton

Magnetic damping is a BIG help. Basically, you have a non-ferrous piece of metal that moves between a pair of magnetic poles. The motion of the non-ferrous metal induces electrical currents in it, which, in turn, interact with the magnetic field to slow the motion of the arm. Net effect is that the scale settles to zero much more quickly.

15 April 2003, 13:51

sonofagun

I SAY MAGNETIC DAMPING REDUCES BEAM OSCILLATION BUT ALSO REDUCES SCALE SENSITIVITY.

DO SCALE MAKERS ACTUALLY BELIEVE THEIR SCALES CAN'T EVER GET OUT OF ZERO? DO WE HAVE A LIABILITY CONCERN OPERATING HERE?

AND OH, THE ADJUSTING FOOT IS FOR LEVELING THE SCALE, NOT ZEROING IT.

[ 04-15-2003, 05:04: Message edited by: sonofagun ]

15 April 2003, 14:39

Ol` Joe

sonofagun can you give a better explaination of the "zeroing" nuts on the scales beam? I`m not sure I have ever seen them and I`ve used or owned a Ohaus 505s from the early 60s thru the RCBS 5-10 and 10-10 and worked with a old lyman of a friends. They all were "balanced" with a few small "pellets" place inside the patten pan plate (?)at the factory.
The scale "should" be balanced/zero`d when level as balance is accomplished with a set wgt or force on both sides of the poise, not by adding / removeing wgt or its position on the beam. As long as the beam or poise isn`t damaged or hindered in some way, or the pellets removed or more added it will go to zero when level. [Confused]

15 April 2003, 15:23

HenryC470

quote:
Originally posted by sonofagun:
I SAY MAGNETIC DAMPING REDUCES BEAM OSCILLATION BUT ALSO REDUCES SCALE SENSITIVITY...

It actually doesn't. As Denton said, the magnetic damping phenomenon depends on the nonferrous piece being in motion relative to the magnets. As the motion slows, the damping force decreases, and at rest, there is no force at all. The scale comes to rest at exactly the same position with or without the damping.

I have a little re-zeroing nut on my scale, and I don't bother with it. Life is too short. If my scale reads 0.3 grains empty, and if I want 22.0 grains of powder, I trickle it in until the scale reads 22.3 grains. It's called weighing by difference, and it's what they taught my generation to do in college chemistry. It gives you the right answer.

H. C.

16 April 2003, 02:25

sonofagun

OK, SO FAR YOUS HAVEN'T TOLD ME ANYTHING I DON'T ALREADY KNOW - I AM AN EXPERIENCED RELOADER AND WAS A SCIENCE MAJOR IN SCHOOL.

LET'S NOT FORGET MY ORIGINAL QUESTIONS:

DO ANY OF YOU HAVE TROUBLE WITH YOUR SCALE MAINTAINING IT'S ZERO?

WHY HAVE THE SCALE MAKERS LEFT OFF ANY ZERO ADJUSTMENT?

SCALES ARE MORE SENSITIVE W/O DAMPING TO ANY BREEZE OR CHANGE IN WEIGHTS - THEY JUST AREN'T ANY MORE ACCURATE(?)

[ 04-15-2003, 17:28: Message edited by: sonofagun ]

17 April 2003, 04:48

RSY

Which scales don't have zero-adjusters on them? The only one I can think of is the Lee scale.

A shortcut on a Lee product??? Say it ain't so.

RSY

[ 04-16-2003, 19:58: Message edited by: RSY ]

17 April 2003, 05:14

tasco 74

MY LEE SCALE HAS A LITTLE ZEROING WHEEL ON THE OTHER END AWAY FROM THE DAMPING MAGNETS. I ALWAYS USE THIS TO ZERO MY SCALE WHEN I RELOAD. WOULD BE NICE TO HAVE SOME SMALL CHECK WEIGHTS THO.

17 April 2003, 06:00

RSY

Regarding the Lee, I stand corrected. Thanks Tasco.

So, the question remains...what scale doesn't have a zero-adjustment?

RSY

17 April 2003, 07:54

bobg

I got a piece of 1/8" steel plate. Cut it 3"x8". Drilled and tapped one end for the adjusting screw. Works great. Sit the scale on it and adjust.

bobg [Smile]

17 April 2003, 08:39

Stonecreek

There seems to be some confusion in the difference in a beam weight adjustment mechanism and a scale body level adjustment.

All of the scales that I know of have a leveling adjustment, which should NOT be used to make up the difference in an out-of-balance beam, but rather compensate for an unlevel table or bench surface. After all, the beam has to be reasonably close to level when it reads "zero", or all weights will be skewed.

MOST balance beam scales used to come equipped with a beam weight adjustment, used to zero a level scale. The answer to sonofagun's question is that manufacturers decideded to drop this nicety in favor of economy, since their experience over the years was that (1) casual reloaders didn't know how to use the adjustment, and (2) with a well-built scale, there is little to get out of adjustment.

As to dampening, I use a magnetically-dampened scale for its speed and convenience, but I would have to agree that the old oil-dampened scales seemed to allow more precision.

Ain't never seen no damn 'lectronic scale what I'd trust to weigh pinto beans.

17 April 2003, 11:19

waitaminit

WOULD BE NICE TO HAVE SOME SMALL CHECK WEIGHTS THO.

Take a little piece of metal and have it weighed by a precision scale owner (apothecary, laboratory, goldsmith).

17 April 2003, 11:45

<brandx>

The magnetic dampening effect is achieved thru the Lenz theorum as discussed above. It ONLY creates a force when there is MOTION, i.e. the damper blade is moving. The most likely method for it to influence the beams resting point is to influence the pivot mechanism. This can be the case where the pivot bearings are not close to perfect, wherein a bit of drag remains and the dampening effect causes the beam to stop out of it's true position.
Levelling... if you do an analysis of how beams work, you will see they do NOT rely on coming to perfect level, i.e. like a 'perfect' teeter-totter. This mechanism will balance at any angle since the COS of the rest angle multiplied by each arm yields the same result as no angle does. A free body diagram will explain this best for those familiar with this analysis, and beams rely on another method to achieve 'sensitivity'. This is a design parameter that is inversely proportional to the cycle time of the oscillations. The more 'accurate' you design the beam the slower it works, nothing is easy.
It is best to have the beam pretty close to level when it is zeroed primarily due to the pivot geometry and this is the purpose of the level legs.
Some scales nowadays do not have the adjusting nuts and do depend on lead shot in the tray holder to set up the balance point. When lead oxidizes it can change weight and you may find it necessary to (usually) add more weight here.
Electronic scales that 'really work' cost a lot of money .... anywhere from $1000- $20,000.
I think it is true that most mfgrs build something to sell at a certain price level, rather than building something to do a job then pricing accordingly.

17 April 2003, 14:10

tasco 74

WAITAMIN I HAVE WIEGHED SOME AIR GUN PELLETS. IT MIGHT WORK TO HAVE ONE OF THEM WEIGHED FOR SURE AND GO WITH THAT. THE PELLETS I HAVE WEIGHED WERE RIGHT ON THE MONEY FOR ADVERTISED WIEGHT.

THE 2ND AMENDMENT PROTECTS US ALL..........

17 April 2003, 14:25

waitaminit

tasco, to my taste, lead corrodes too easyly - I would go for a chip of stainless steel.

[ 04-17-2003, 12:48: Message edited by: waitaminit ]

17 April 2003, 14:29

sonofagun

[QUOTE]Originally posted by brandx:
This mechanism will balance at any angle since the COS of the rest angle multiplied by each arm yields the same result as no angle does.

IN OTHER WORDS(?) As long as the scale is zeroed and the same level setting is maintained, it should give correct readings, right?

ALSO:

"Electronic scales that 'really work' cost a lot of money .... anywhere from $1000- $20,000."

THAT'S INCREDIBLE, BUT I HAVE BEEN WONDERING HOW RELIABLE THESE ELECTRONIC SCALES FOR $200 OR SO ARE.

17 April 2003, 14:36

sonofagun

quote:
Originally posted by Ol` Joe:
sonofagun can you give a better explaination of the "zeroing" nuts on the scales beam?

TAKE A LOOK AT A HORNADY MODEL "M" OR THE OLD HERTER'S OR REDDING SCALES - THEY HAVE THEM.

18 April 2003, 03:23

Jameister

"When lead oxidizes it can change weight and you may find it necessary to (usually) add more weight here"

If lead oxidizes from Pb(s) to Pb(0) it will gain weight as a solid, requiring removal of pellet weight as the lead oxide (a white powder)adds the weight of oxygen atoms to the weight of the lead atoms. If there is abrasion removal of the lead oxide, then you would add lead to replace the removed lead oxides.

In my little scale pans, there are different sized shot, and there is a simple method of replacing a smaller or larger one with several different sizes to get exact measurements.

good thread!!

18 April 2003, 03:45

Stonecreek

BrandX: In practical terms, I agree that the balance beam need only be "close" to level for a scale to perform passably.

However, as the zeroed beam angle increases from the horizontal, the difference in beam deflection from zero with a given weight decreases, making the scale less sensitive. A balance beam is most sensitive when it is perfectly horizontal, just as it is more sensitive the longer it is.

In regard to dampening, while I know that there is actually no difference in the ultimate accuracy of a scale whether oil or magnetically dampened, the oil dampened scale is a bit less sensitive to air disturbance when resting at zero, which can make its practical accuracy better under some conditions (but this is truly splitting hairs and is of no great moment).

For $2,000, one of them damn 'lectronic things might be okay to weigh aspirins or or such.

18 April 2003, 04:12

Art S.

As to the issue of standard weights, every reloader has boxes of them. Grab a box of 22 or 6mm match bullets. You will be amazed how close they are. Most cheap (all reloading scales) balances are not accurate to more than a 10th of a gr. It is seldom that I have ever seen high quality match bullets this far off. Use five from each box of several different brands and weights to take out manufacturing tolerences. I think you will find them remarkably accurate. If you get a significant consistent offset, your scale is out. Use bullets near the powder charge range you are interested in. I use 50-85 gr bullets to check.

If you are really interested, any scientific supply house sells standard weights and sets at a fairly reasonable price. Go see your local high school chemistry teacher to get a catalog. They usually come in a little padded box complete with a cotton glove to avoid skin oil, sweat and tarnish.

18 April 2003, 04:14

Big Bore

Well, all I can say is that the directions with my old Lyman-Ohaus scale tells you to zero the beam with the adjustment foot on the front of the scale. Is that leveling the scale, yes, but it also zeros the scale. It being magnetically dampened just slows the oscillations; it does not make it any less sensitive IMO. I did not trust the new electronic scales for many months until it proved to me that they were just as sensitive and reliable as the balance beam. A good set of scale check weights are a good investment to make sure that your scale is measuring accurately each and every time you use them.

18 April 2003, 08:24

shootaway

I have trouble with mine.If you sit down and load many rounds it is difficult not to disturb the scale.This is a mechanical scale by the way.It is difficult to pin point when the scale has been disturbed,and if it has the rounds that follow will be different than the ones before.To me this is a big headache.Does anyone understand what I am saying? Any solutions?

19 April 2003, 07:03

<brandx>

Stonecreek... yes and no. Within any reasonable angle close to zero (horizontal) the angle at which it 'zeroes' really does not effect the sensitivity. The length of the beam has no influence on sensitivity either...actually makes it harder to optimize design to some amount due to increased moment of inertia of the beam. What it does do is provide more movement for a given displacement, i.e. makes it easier to see which could be called 'usable sensitivity'. Key fact here is that a balance beam is NOT like a simple teeter totter... there is more than meets the eye on beam scale design.
take a look here: www.askfirst.com/prometheus

19 April 2003, 07:43

sonofagun

THANKS GUYS FOR ALL THE INPUT.

TO EXPAND OUR DISCUSSION A BIT - IS ANYONE HAVING PROBLEMS (OR NOT) WITH THEIR ELECTRONIC SCALE? WHAT BRAND IS IT? WHAT KINDA PROBLEMS (OR NOT)?

19 April 2003, 08:59

Big Bore

The only problems-and these are user error-that I have had with my Pact scale is trying to plug it in, turn it on, calibrate, and start loading. Then trouble occurs. If you plug it in and turn it on, wait thirty minutes for it to stabilize-like the directions say-then calibrate it and start loading, there are no problems. Also, make sure there is no fan or heat-A/C register nearby-like in my case, directly overhead-which when it comes on will play havoc with readings. I have found that if I don't make those errors, then the scale works perfectly.