[Mad Trapper]

Found a Ohas/RCBS model 304 scale , yippee!

What do people use/recommend on the cheap for check weights?

In old days we used new nickel, that was 4.9850 g = 76.93 gr.

We had scales at work to +/- 0.0001 gr and the nickels were pretty good to 0.0002 g in accuracy and precision.

If anyone has a good analytical balance would be interested to know current masses accuracy/precision of current coinage.

Thanks!

MP

 

[JayKosta]

Having the scale be reasonably accurate (within plus/minus 0.2 grain is fine), BUT having it be repeatable is more important.
If several separate weighings of the same object don't give the same result then something is wrong.

For general reloading we want to get weights to be consistent, and that's why repeatability is so important.

If getting high-accuracy weighings is really a concern - e.g. precious metals or gems, then that's another matter.

Jay Kosta
Endwell NY USA

 

[Rich D]

US Mint info in grams:
penny-2.500
nickle-5.000
dime-2.268
quarter-5.670
half-11.340
This is for new 2016 coins. Any circulation would reduce weights. All calibrations should be done with multiple weights to assure linearity. Another alternative is RO water. If you have a syringe, 1 ml = 1 gram.

 

[POLACK]

http://www.ebay.com/itm/Vintage-OHA...315230?hash=item1c7218d89e:g:tc8AAOSw8oFX0b-p weights
http://www.ebay.com/sch/i.html?_fro....TRS0&_nkw=ohaus+scale+check+weights&_sacat=0

 

[Mad Trapper]

US Mint info in grams:
penny-2.500
nickle-5.000
dime-2.268
quarter-5.670
half-11.340
This is for new 2016 coins. Any circulation would reduce weights. All calibrations should be done with multiple weights to assure linearity. Another alternative is RO water. If you have a syringe, 1 ml = 1 gram.

Water calibration is crude for a scale as you need volumetric glassware at 25 oC.

We used to do the reverse calibration, that is calibrate microliter pipettes with a chemistry analytical balance, at 25 oC.

 

[Mad Trapper]

Having the scale be reasonably accurate (within plus/minus 0.2 grain is fine), BUT having it be repeatable is more important.
If several separate weighings of the same object don't give the same result then something is wrong.

For general reloading we want to get weights to be consistent, and that's why repeatability is so important.

If getting high-accuracy weighings is really a concern - e.g. precious metals or gems, then that's another matter.

Jay Kosta
Endwell NY USA

Having the scale be reasonably accurate (within plus/minus 0.2 grain is fine), BUT having it be repeatable is more important.
If several separate weighings of the same object don't give the same result then something is wrong.

For general reloading we want to get weights to be consistent, and that's why repeatability is so important.

If getting high-accuracy weighings is really a concern - e.g. precious metals or gems, then that's another matter.

Jay Kosta
Endwell NY USA

Jay, points taken and understood. Accuracy is average close to the true (or some cases mean) value. Being precise is a low SD relative to the mean.

A quality scale can be very precise but not accurate due to calibration. When calibrated it will be accurate and precise.

A cheap scale can be accurate but not precise (avg of weighings close to true value), or both inaccurate and imprecise. In the former case calibration will get average weights closer to true mass but will still have high +/- relative to true mass.

The Ohas 304 is a very precise scale by reloading standards, if adjusted it is also very accurate.

I do not have calibration weights so am wondering how precise (low SD) and accurate (in this case close to mean weight for say 10 coins) current new coins are? If low SD close to mean mass, what are mean masses?

 

[Mad Trapper]

I used to teach college chemistry, hence the question of BOTH accuracy AND precision.

Here is a good example everyone here can relate to. You shoot at a target 3 times with 5 different guns.

The 1st gun hits the target low left 1st shot but is off the rings. 2nd shot is high right on the 2 ring. Third shot is off target. This gun is not precise, nor accurate.

The 2nd gun shoots a 4 inch triangular group, high right. It is not precise, nor accurate. Note that it is accurate to the groups mean.

The 3rd gun only hits the 5 ring three times, 120 degrees apart around the X, but the group average is dead on X. This gun is not precise but is accurate.

The 4th gun also hits the 4 ring, all shots nearly in the same hole. This gun is not accurate, but is very precise. Note that is also very accurate to the groups mean.

The 5th gun hits the X all three times. It is BOTH accurate and precise, and accurate to the groups mean.


For firearms it is easy to adjust a precise gun (guns 4 and 5). You adjust the sights to zero. Guns 2 and 3 will never be precise but can be adjusted for accuracy. Gun 1 has problems sighting in/calibrating won't help


So.......back to original question concerning scales.

The OHAS/RCBS 304 balance in working order is a VERY precise scale for reloading, it's accuracy depends on calibration with accurate check weights (weights are accurate or not, no precision involved).

Concerning using coins as check weights. In the past I found the mass of nickels to be BOTH precise and accurate. That is repeatable mass on an analytical balance with say 10 different nickels, AND accurate as each nickel was +/- 0.0002g of the average.

The above was part of an exercise in freshman chemistry. Student weighed coins, steel shot, and beans. Then reported on accuracy and precision for each group of 10.

The nickels were precise and accurate, the beans were neither.

This was years ago and don't have uncirculated 197? nickels handy.

 

[timrb]

A nickel, and probably any US coin, is not nearly good enough to be used as a check weight for reloading purposes unless it is first weighed on a known-accurate scale and the weight recorded.

A US nickel weighs, by spec, 5 grams. By law, this weight is not allowed to vary by more than .194 grams.

https://www.law.cornell.edu/uscode/text/31/5112
https://www.law.cornell.edu/uscode/text/31/5113

5 grams is about 77.16 grains; .194 grams is about 3 grains.

For no particular reason, I weighed a dozen nickels on my RCBS 505 scale. The coins were not uncirculated, and dates ranged from 1964 to 2015. Weights ranged from 76.7 to 77.9 grains. So all these coins were well within spec.

If you need check weights, you probably should just buy a set.

Tim

 

[Rich D]

Water calibration is crude

But using a dime isn't? As 25 degrees is near room temp(why they picked it for the base line), it is better using a 5, 10 and 25ml syringe than a nickle, dime and 2 quarters that have been touched, dropped, or otherwise altered. Glassware is calibrated by filling with a known weight of de-ionized water from a calibrated scale or balance and marking a line, and you can check the calibration of glassware, pipettes, and micro-pipettes with a balance or scale.

 

[Mad Trapper]

But using a dime isn't? As 25 degrees is near room temp(why they picked it for the base line), it is better using a 5, 10 and 25ml syringe than a nickle, dime and 2 quarters that have been touched, dropped, or otherwise altered. Glassware is calibrated by filling with a known weight of de-ionized water from a calibrated scale or balance and marking a line, and you can check the calibration of glassware, pipettes, and micro-pipettes with a balance or scale.

It's not feasibale to do at home calibration with "pure" water for a scale. You need calibrated volumetrics and know how to use them. Also when dispensing a "grain" mass of water there is a lot of variation due to just technique with the best equipment. And how accurate is your thermometer? For both the water and the glassware.........

I did find new clean nickels in the past to be usable check weights, consistently 4.985 grams. Is this still so? That would get me started on my "new" scales clean up/setup.

Before use I'll clean up a few pet nickels, chop some into polished pieces. Then visit my analytical chemist friend to: mass them all to 0.0005 gram, store with love in clean kleenex lined box, and only handle them with clean tweezers.

 

[graystoke3]

Use an unfired projectile...that is how I periodically check my balance beam scale. It works and it is reasonably priced

 

[Mad Trapper]

Use an unfired projectile...that is how I periodically check my balance beam scale. It works and it is reasonably priced

I like that.

I've checked lots, of lots, and found many quite uniform. Most are bullets are heavier than suggested load data even 22 cal slugs.

The nickels will take a back seat to the Noslers until I get some good weights.

BTW, anybody use a Ohaus/RCBS 304? I had one years ago and really liked the little platform to put the trickler on while adding the last few granules.

Too bad they discontinued it. Their similar science beam balances are a bit too large.

 

[wxl]

My Chargemaster has calibration weights and I do check calibration usually before a load session.

I weighed a nickel and a dime and keep the values posted on my Chargemaster (and the same coins). Periodically I drop one of the coins on the tared scale for both a check on weight accuracy and if I am getting repeatable readings. If my coin is still within +/- 0.1 grain, I am good to go. I use whichever coin weight is closes to my desire charge weight.

 

[Tenboremag]

I use the Lyman check weights.

 

[nf1e]

I use the Lyman check weights.

Me too.

[URL=http://s1180.photobucket.com/user/nf1e/media/IMG_0432_zpsba1g5quz.jpg.html][/URL]

 

[4Quangs]

I've used dimes as check weights. Just pick up a handful of new dimes at the bank, weigh them on your scale and spend the outliers on donuts and use the rest as check weights.

I only reload 30 caliber, so I check my balance beam with one dime (35 grains) and two dimes (70 grains). If the scale is correct for both, then I'm reasonably sure the scale is measuring linearly is good to do go.

 

[Rich D]

store with love in clean kleenex lined box, and only handle them with clean tweezers.

Very, very important, no matter what you use for weights.