Calibrating JS-100xV powder scale

[tl-driver]

Evening folks,

I recently received my JS-100xV powder scale from brianenos.com. I am seeing fluctuating readings when testing the accuracy of the scale with the 100g weight

that ships with the scale. After switching out batteries, and recalibrating (3) times I am seeing readings anywhere from 99.97g to 100g. Each of these readings

is of course after removing the weight, waiting for the scale to return to zero and then placing the weight on the scale again. My biggest concern is that the

readings are not consistent. Has anyone had similar experiences ? Is this normal ? Any help or suggestions would be greatly appreciated.

Thanks,

[Too_Slow]

First off make sure the scale is pretty much level and then also make sure that there isn't a lot of air flow hitting it such as from an AC or heating vent.

Brian K.

[98sr20ve]

Is it warmed up for very long?

[tl-driver]

It had probably warmed up for a couple minutes. Also I made sure it was on a level solid desk and away from any vents.

I did that after I realized that just simply exhaling on the scale will affect it.

Is it warmed up for very long?

[98sr20ve]

Have you checked it for 10 mins or even longer?

[CZinSC]

Same exact problem here. I've tried everything i can think of. Turned off all electricity, closed garage door to prevent any breezes, made sure it was on a level surface, etc. I get flucuations +/- .3 grains all the time. I was so fed up I bought the RCBS balance beam scale to put my mind at ease that my powder drops were accurate. I then tried a friends Frankfort Arsenal DS750. It is spot on, no flucuations, just steady accurate numbers. I picked one up from MidwayUSA. For half the price of the JS100xV.

[noylj]

Digital (electronic) balances should be turned on and left alone for at least 30 minutes for thermal equilibrium. If balance can actually read ±0.01gn, then you need a very heavy table (granite is best) on vibration dampening rubber under legs and a wind screen. Just you breathing on it will make it fluctuate.

You are NOT touching the check weight, are you and adding oils and samples of DNA to the check weight?

Why are you so concerned over ±0.01gn, when ±0.1gn is all the precision needed for reloading?

Just checked. The specification says the balance is rated to ±0.1gn. Did it come with a gram check weight and you are reading the 0.01 gram?

Get rid of all sources of vibration and breezes. WEigh the check weight 20 times. Calculate the average and the Std. Deviation. Divide the S.D. by the Average to get the Coefficient of Variance. Should be under 3% (0.03).

Edited August 21, 2010 by noylj

[tl-driver]

Digital (electronic) balances should be turned on and left alone for at least 30 minutes for thermal equilibrium. If balance can actually read ±0.01gn, then you need a very heavy table (granite is best) on vibration dampening rubber under legs and a wind screen. Just you breathing on it will make it fluctuate.

You are NOT touching the check weight, are you and adding oils and samples of DNA to the check weight?

Why are you so concerned over ±0.01gn, when ±0.1gn is all the precision needed for reloading?

Just checked. The specification says the balance is rated to ±0.1gn. Did it come with a gram check weight and you are reading the 0.01 gram?

Get rid of all sources of vibration and breezes. WEigh the check weight 20 times. Calculate the average and the Std. Deviation. Divide the S.D. by the Average to get the Coefficient of Variance. Should be under 3% (0.03).

Good point on adding oils and samples of DNA, but unfortunately the scale is often measuring less than the 100g weight. (ex. 99.97g, 99.96g)

I am not sure how to answer your question about +-0.01gn as my concern is over the fluctuation when measuring the 100gram weight which is anywhere

from 99.96 - 100.00 grams.

Are you saying that the fluctuation when measuring the 100gram weight would not be a problem when measuring in grains ?

Sorry if this is not clear.

[yoshidaex]

Would it be possible that 100 gram weight is not truly 100 grams?

[98sr20ve]

Good point on adding oils and samples of DNA, but unfortunately the scale is often measuring less than the 100g weight. (ex. 99.97g, 99.96g)

I am not sure how to answer your question about +-0.01gn as my concern is over the fluctuation when measuring the 100gram weight which is anywhere

from 99.96 - 100.00 grams.

Are you saying that the fluctuation when measuring the 100gram weight would not be a problem when measuring in grains ?

Sorry if this is not clear.

You have a .04gram variation.

If the weight is actally 99.98 grams its a .02 gram variation

.04 grams is .6 grains

.02 grams is .3 grains

For me nothing I weight in the 100 grain range is that critical. All I weight is bullets. I would want to take the scale and weight something in the 5 grain area and see if it's consistent. Unless you have a actual check weight of that size you won't know if it's accurate. Consistent can be just fine but it's only good if you actually work things up slowly and safely. I would get some check weights and use them. The blue tip on the dillon tube is about 5 grains.

[sperman]

How do you leave an electronic scale on for 30 minutes to warm up when it shuts off automatically after 5 minutes?

[98sr20ve]

I thought you could disable the auto off feature on that scale. Thats what the website says.

[tl-driver]

Thanks to all for the help and advice. I have decided to return the scale for a refund and start looking for another

digital scale. Thanks again ..

Best Regards

[benos]

Sorry, didn't see this.

I'm not sure what to say. Out of the crapload of scales I've sold, only an extremely small percentage have been returned due to reported inconsistent readings. And all but two have worked fine for me after replacing the batteries and recalibrating. One returned scale had an obviously defective load cell, that was probably damaged in shipping. And the other did 'wander' more than it should have.

I've been playing with a returned scale this afternoon. Recalibrated it, and it seems to work fine for me. Setting the 100 gram test weight on and off 20+ times - it reads from 100.03 to 100.05 every time. Which is more than acceptable for the kind of accuracy we require. So I'll sell it in my Blem Store for half price.

From Lee Love's excellent Tips for Electronic Scale accuracy, on scale test weights:

Always use the calibration weight(s) that came with your scale. Depending on the resolution of the scale, the

“class” of calibration weight(s) that come with it will vary. In the United States, three classifications are used.

• ASTM E 617-97, Classes 0 through 7; and

• OIML R111, classes: E1, E2, F1, F2, M1, M2, M3.

• NIST Class F; (Only used for commercial weights & measures testing)

If you want to read a complete table comparing these weight classes go to;

http://ts.nist.gov/WeightsAndMeasures/caqmass.cfm

Or

http://www.precisionsolutions.com/docs/prodinfo/ReferencePDFs/ASTM_reference.pdf

Lower resolution scales may only come with ASTM Class 6 (equivalent to OIML class M2) calibration

weights. A 50g Class 6 calibration weight can vary by as much as ±7mg (±0.007g / ±0.107grain) and a 100g

calibration weight can very by as much as ±10mg (±0.010g / ±0.154grain). That doesn’t sound like much but

when you are calibrating your scale, it can make a significant difference if you use the calibration weight from

another scale.

I attached the entire article.

be

scale.pdf

[famous187]

I recieved mine on Monday and just tried it out last night. Mine is doing the exact same thing. I got a reading of about 99.96-99.97g everytime I put the 100g weight on it. I replaced the battery and that made no difference. Then I recalibrated the scale per the directions in the manual. After doing that I was getting 100.00g consistently for the next few mins. I tried it again a couple hours later and it was reading high, around 100.03-100.5g. So, I recalibrated it again and it was reading 100g, tried it again a couple hours later and now its back to 100.03-100.05g. The box says it should read within .01g so does this indicate a problem with the scale? Is it off enough to pose a safety issue?

-chris

[benos]

I recieved mine on Monday and just tried it out last night. Mine is doing the exact same thing. I got a reading of about 99.96-99.97g everytime I put the 100g weight on it. I replaced the battery and that made no difference. Then I recalibrated the scale per the directions in the manual. After doing that I was getting 100.00g consistently for the next few mins. I tried it again a couple hours later and it was reading high, around 100.03-100.5g. So, I recalibrated it again and it was reading 100g, tried it again a couple hours later and now its back to 100.03-100.05g. The box says it should read within .01g so does this indicate a problem with the scale? Is it off enough to pose a safety issue?

-chris

Not at all. If you take the variable you saw, and apply that percentage to the actual powder charge weight you'd use for loading pistol or rifle ammo (some grains as opposed to 100 grams) you wouldn't even be able to detect a difference in consistency. Even though in Lee's article he said he calibrates the scale before each time he uses it, if I were using that scale, I might calibrate it now and then, but mostly I'd just turn it on, wait a minute (it actually warms up really fast), and push the zeor button and start weighing with it.

be