Balance beam scale

[DaggerBlade]

I am looking for a good way to check the accuracy of an RCBS balance beam scale. Any suggestions?

 

[bsoileau24]

http://www.midwayusa.com/product/493216/rcbs-standard-scale-check-weights-605-grains

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[highstandard40]

http://www.midwayusa.com/product/493216/rcbs-standard-scale-check-weights-605-grains

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That's the one I use as well.

 

[beauxdog]

Louisiana Gun has several packs of check weights for use in determining the accuracy of your scale. Using a know weight lets you know that your scale is functioning as it should and then you can be assured you are throwing the correct amount of powder.

Bryan Guillory
Louisiana Gun
127828 Jefferson Hwy.

 

[Jmfox3]

Use a bullet to see if you have a "big" problem.

 

[highstandard40]

Use a bullet to see if you have a "big" problem.

I have seen factory produced jacketed bullets off of their advertised weight by as much as 3%.

 

[Bayou52]

To make sure that when my 5-0-5 scale reads 20 grains, for example, that it is actually 20 grains, I use Lyman check weights at the beginning if each reloading session.

The checkweights affirm the accuracy of the scale. I typically zero my scale using check weights for the load I'm using.


http://www.midwayusa.com/product/612694/lyman-scale-weight-check-set


Bayou52

 

[oneshy]

A new nickel weighs 5 grams. Cheapest, quickest way for a quick check.
77.16 grains.

 

[DBMJR1]

I wonder if I'm the only one with two scales on his bench. An Omhaus and a Lyman. Plus I have a set of 'scientific' check weights. Designed for chemists, these weights are in grams, not grains.

Actually I have a third scale. An electronic scale of much higher capacity that I use for mixing alloys.

 

[highstandard40]

A new nickel weighs 5 grams. Cheapest, quickest way for a quick check.
77.16 grains.

That will only get you close. There is no way that a US Treasury nickel is going to be produced to the same accuracy standards as a precision set of check weights. I just set my scale with a set of precision weights and checked a brand new nickel. It was a full 2 grains short of the stated 5 grams (77.16 grains).
There are no accurate shortcuts here. Precision check weights are the only way to be accurate.

 

[highstandard40]

I wonder if I'm the only one with two scales on his bench. An Omhaus and a Lyman. Plus I have a set of 'scientific' check weights. Designed for chemists, these weights are in grams, not grains.

Actually I have a third scale. An electronic scale of much higher capacity that I use for mixing alloys.

Between my loading bench and my casting bench, I have 5 scales. An RCBS 510 beam scale for measuring powder charge weights, an old Ohaus twin beam with a capacity of about 3000 grams for bulk weighing, a small digital postal scale for mixing alloys, an RCBS 1500 digital for weight sorting components, and a spare 500 gr digital scale for a backup.

 

[mineralman55]

If you have access to a laboratory pipette, zero your scale, put 1 ml of distilled water in your powder pan. Weight it. It should be 1 gram, or 15.4 grains. Put another 1 ml in the pan, weight it, should now be 2 grams, or 30.8 grains. Do that up to 5 ml or 77.09 grains. Make an X-Y plot with the scale's measurements on the X-axis the water weight on the Y-axis. Now you have a calibration curve. Enter the X axis with whatever reading your scale is, and read the "true" weight in grains on the Y-axis.

It won't be a perfect calibration curve, but at ambient temperatures and pressures you don't have to worry that water's density varies from 1 gm/ml.

 

[Win1917]

I use an RCBS 10-10 and religiously pull out the check weights every time it gets used for two reasons. One obviously first and foremost is to make sure the scale is working properly. Secondly though it can help provide a second check that the scale is set right. So if the load to be charged is 45.5gr, pull out 45.5gr of weights and calibrate the scale instead of using say a 10gr weight to calibrate then dial up the scale to 45.5. Even if the check weights aren't exact, just get close. So if the charge is 45.1, use 45 to calibrate then just make the tenth adjustment. There's less chance of making mistake that way than when making large adjustments.

I never thought about the redundancy aspect of calibrating a scale that way until a saw a friend of mine on two different occasions misread the hash marks on the scale and undercharge cases by 10 grs! Thank god they weren't 10gr over charges and obviously the true solution to the problem is to engage the brain when adjusting the scale, but if he'd calibrated at or close to the correct charge, he would've caught the scale adjustment mistake before pouring powder.

 

[noylj]

One really good check weight is all that is required. Standard check weights are "good enough" for reloading. If the beam can read a 50-100 grain check weight accurately, the lower weights will take care of themselves. If you want to do metrology, weigh each check weight and combination of check weights and plot the check weight vs. the balance reading on a graph and repeat every year. Digitals have the benefit of being easy to read.
Anything but a certified check weight is only good enough to tell you if you are "in the range," and not how accurate your balance is.
Some rules:
Keep the balance in one place and level, such that it can't move easily.
Keep the beam off the fulcrum unless in use
Keep the balance covered unless in use
Keep the balance clean and free of aerosol mists
Keep the balance at eye level and be sure you can easily see the balance point/line.