Scale Calibration?

[10-x]

Anyone know of a company that will calibrate reloading scales in the S.E.?
Thanks:-D

[xr650]

I use RCBS check weights. I have two sets so I can put the correct load wght on my scales.
If this is a balance beam scale your zero will fluctuate with the levelness(is that a word?) of your scale.

[billyb]

if you have rcbs scale email them or call and they will give you a return number and address. i sent mine to ohous not shure about the spelling . returned a new scale no charge. if not rcbs contact the the people with the name on the scale. Bill ps ohus is in new york state ?

[1hole]

Assume you mean a beam scale? If so, there is no way to recalibrate them, they have no adjustments to do so. Only a new beam can change the point at which the beam becomes balanced in use. I wonder how far off, and at what part of full scale, your scale's error is?

I believe people may confuse the qualities of pure accuracy vs. repeatability. Within fairly large errors, say 1/2 gr., pure accuracy isn't much of a concern to a reloader. We cannot accept or depend on anyone else's powder charge data as gospel anyway. We must approach high pressures from below, moving carefully until we find our own weapons limits when using our own tools. That way, it won't matter much what the limit is (or what the scale says it is) but we must be aware that charge IS the LIMIT for us!

But, scale repeatability is critical to a loader! Once we find the limit it becomes imperative that we can duplicate it, time after time, without going over. Repeatablity problems usually come from dirty or damaged pivot pins or bearings, placing the beam to far forward or back and causing the pivot pin to rub against the bearing housing, or changing/stray stray air currents.

Drifting caliberation and/or changing zero is why I refuse to use any digital scale for measuring powder. They lack the level of reliable repeatability I demand of a reloading scale.

[xr650]

1hole,
I have no info on other scales.
I can calibrate my Redding scales two different ways.
1) I can use the leveling screw as the beam is stationary at load.
2) My scale has two nuts on the end of the beam to accomodate calibration.

[10-x]

Have 2 scales a RCBS 10-10 and an OHAUS beam scale with cover that I p/u at a yard sale.
Reason I prefer to have them calibrated is the RCBS has not been used in 15 years and I have no history on the OHAUS.
Thanks for the RCBS info, I'll send it back to them and guess the OHAUS to whoever owns them now.
Just looking for something close like S. GA or N. Fla.:drinks:

[xtimberman]

You can get a set of check weights and do it yourself. The instructions tell you how to test various settings up and down the beam.

http://www.midwayusa.com/esearch.exe/search?search_keywords=lyman+check+weights&category_selector=all_products&Click+to+Begin+Search.x=12&Click+to+Begin+Search.y=10

xtm

[1hole]

xr, I believe both the screw and nuts you mention are only for leveling and zeroing the scale, not for calibration, as such.

[xtimberman]

xr, I believe both the screw and nuts you mention are only for leveling and zeroing the scale, not for calibration, as such.

You level the scale with all the beam settings zeroed-out - then you use proscribed combinations of the weights to check a wide series of beam settings to see if the settings jibe with the actual known weights of the set. If they jibe, you have an accurate scale - if they don't, you will know exactly how far off the beam settings are, and can make adjustments accordingly when you weigh charges.

xtm

[Maven]

10-x, Call RCBS' toll free tel. no. about the 10-10 scale (made by Ohaus). RCBS will give you an order no. and an address to send the 10-10 to (Ohaus in N.J.). If you google Ohaus, you can probably get their tel. no. and ask them about refurbishing the [covered] beam balance too.

[xr650]

xr, I believe both the screw and nuts you mention are only for leveling and zeroing the scale, not for calibration, as such.


You level the scale with all the beam settings zeroed-out - then you use proscribed combinations of the weights to check a wide series of beam settings to see if the settings jibe with the actual known weights of the set. If they jibe, you have an accurate scale - if they don't, you will know exactly how far off the beam settings are, and can make adjustments accordingly when you weigh charges.

xtm

I agree with both of you.
I use check weights for every load change. My shelf that holds the scale is metal. It will tend to have it's postion changed from time to time.
Any bench mounted measuring instrument needs to be recalibrated any time the instrument is moved.

Oh, by the way I'm not starting an argument just cussing and discussing. :drinks:

[1hole]

"Oh, by the way I'm not starting an argument just cussing and discussing. "

Ditto.

Sure, we can use calibration/test weights to see just how accurate a scale is. What we really can't do is change (calibrate) that error out. For instance, you might find that a 100 grain check weight shows as 101 grains on the scale. You could adjust the nuts to make it read correctly at that point. But, if you then recheck the zero will find that it is off, probably by the most of the amount you corrected for.

The accuracy of full scale calibration is determined by the beam itself and/or the slider weights. If the scale is reading low we could, I think, file off a bit of one of the sliders to allow a properly zeroed beam to raise for proper reading but that would be a tricky thing; which one should we file down? Better to leave it to a factory calibration team to calibrate those things, IMHO.

And, by the way, magnetic damping of a beam is just that, damping. The magnets have NO effect on a non-swinging beam, therefore they CANNOT affect accuracy.

[xtimberman]

Oh, by the way I'm not starting an argument just cussing and discussing.

Well, I'm mad and I'm not taking it anymore! :-D

I just took a close look at my 35 year-old RCBS scale ( a Ohaus-patent 5-10?) and there is a way to re-calibrate it if it is off! The copper plate at the far end of the beam can be moved back and forth to accomodate minute movements. It is held in place by a phillips screw tightened onto a milled slot - and loosening this screw will allow you to slide the plate either way to slightly lengthen or shorten the lever arrangement of the balance beam and have the readings jibe with the check weights.

My scale has remained accurate according to the check weights, so I choose to not fool with this adjustment - which looks like it could become a tedious time-consuming project.

xtm

[1hole]

"I just took a close look at my 35 year-old RCBS scale ( a Ohaus-patent 5-10?) and there is a way to re-calibrate it if it is off! The copper plate at the far end of the beam can be moved back and forth to accomodate minute movements. It is held in place by a phillips screw tightened onto a milled slot"

Interesting find xtm. And that adjustment feature should do it. So, I just took a closer look at my own scales.

My very accurate 43 year old Lyman/Ohaus "M-5" beam's copper plate is riveted hard into the left end of the beam and is totally unmovable.

On the other hand (scale?) my 40 year old Herter's "MS4" has the copper plate screwed to the beam just as your's is. Don't know if there is a slot allowing for adjustment under it or not, it's always been dead on and I'm not about to touch it, but it may be so.

So, I guess the actual answer to possible home calibration really is, "How is your scale made?"