THR myth confirmation/busting - digital scale accuracy

[Walkalong]

My beam scale will react to one granule of powder. But again, if it isn't repeatable, it doesn't matter. Whatever scale you use to to be repeatable at the charge weight in question.

Whether my 44.8 Gr .308 load on my scale is really 44.7, 44.8, or 44.9 Grs is not as important as if it is safe, shoots great, and my scale repeats it every time.

Sounds like you asking people to take a charge, and weigh it over and over, to see what the scale does each time? Correct?

 

[Reloadron]

Already did that......I'm guessing you want me to post 10 more photos?

Otto, actually I would prefer 20 more images and a paragraph with each one including date, time and temperature. Additional information like relative humidity would be much appreciated. Take the readings about 10 min apart also if possible.

Seriously I have a set of the RCBS scale check set weights. Same delux check set you were kind enough to use. Prior to my retirement last year I dragged the set to work and ran then through our lab. Yes, a real live lab that does real live calibrations with traceability and all that wonderful calibration stuff.

I have to give RCBS credit. I haven't a clue who really makes this set but it is quite accurate. In every case the actual weights were well within a 10:1 test uncertainty ratio. More than adequate for any person wanting to check a basic scale for hand loading anyway.

Thanks for posting the images and taking the time to do so.

Ron

 

[Otto]

Otto, actually I would prefer 20 more images and a paragraph with each one including date, time and temperature. Additional information like relative humidity would be much appreciated. Take the readings about 10 min apart also if possible.

OK, let me find my lab coat and pencil protector first. I'll will also have to construct a 'clean room' so there's no contaminates.



Ohaus makes the RCBS check weights or at least used to.

 

[JimKirk]

I can no longer offer any digital scale information as I no longer own a digital scale. I did own an off name digital, this was well over tens years ago. It would not read my test weights as close as I felt I wanted for my loads. I never did test it in the manner that BDS and others are doing. I do believe that the digital scales made today are better than those of the time period I owned one. I believe that any digital product(camera, phone, watch... ) made today, is cheaper and more accurate than of the past period.

Thanks to all those that are doing such test... I may again own a digital scale based on these test....

 

[Peter M. Eick]

Ok I will play.

Scale is my RCBS Electric "Powder Pro" made by pact. I have had it since around 2000 and back then it was just the digital scale for the Electronic dispenser. Price paid was around $150 as I remember.

The second scale is my 1010 RCBS. Bought maybe 7 years back when the last time folks questioned the accuracy of digital. Rarely used it was about $100 on sale as I bought it on a whim.

Paper is copy paper by Sustainable forestry 92 bright 20 lbs, 500 sheets per ream.

78F AC running, 52% humidity.

Both scales say the resolution is 0.1 grains

Both check out fine with a 1 grain and .5 grn test weight

The RCBS digital has an issue that charges less than 0.5 grns are tare-ed to 0 grns so I put the 1 grn test weight in it. Otherwise it would not see the paper.

The 1010 detected 1 piece of paper and 2 pieces measures about 0.07 of a grain (interpolating the scale bar on the tenths wheel).

The RCBS Digital detected and switched to 0.1 grn at 2 pieces of paper.

It was extremely repeatable in both cases. 1 piece of paper would not trip the digital but could be seen on the 1010, 2 pieces could be seen and measured on both.

This is why I gave up on a balance scale years ago and stayed with my digital. It has held up for years with no issues and no problems. I just looked on midway and they still list it for $175. It is a bargain if you ask me.

 

[HJ857]

I have the RCBS 750 digital and have been using it for perhaps since 2009 or 2010.

1 piece of paper will cause the display to very briefly flicker to 0.1 and than back to 0.0.

If I put the smaller check weight in it reads 308.5 grains, when I add that piece of paper it immediately reads 308.6 and then ticks up to 308.7 and it does that every time.

 

[rcmodel]

Mmmmmmm?
OK, I got up off my butt long enough to try the paper square test.
Thanks for that bds!

My ancient Cabala's brand (PACT made) digitals will not weigh 1, 2, 3, 4, 5, or 6 1/4" sq. pieces of Post-It note paper.

However it will weigh a 5 grain check weight over & over again all day.

Doesn't worry me too much if it won't will weigh a pencil mark on a piece of goose down.

It does what I need it to do, which is to very quickly get a ball-park figure while setting powder measures & stuff.

When I get close, I use the old RCBS 5-10 to get down to the nearest gnat scat dropping on the final powder measure setting.

The beam scale is too slow to put up with after have used even a crappy digital scale for stuff like that for many years.

rc

 

[rg1]

Pact Digital Precision 120 volt-no battery, bought in 1994 very shortly after Pact introduced electronic scales for the reloading market. It has weighed lead shot charges, cases up to 50 BMG, bullets up to 647-700 grains, loaded rounds, thousands of small and large powder charges and it matches perfectly my Lyman Check weights.
Grabbed a sheet of printer paper and cut roughly into 1/4" squares. 3 pieces and it reads 1/10 grain every time. 6 pieces and it goes to 2/10 of a grain every time.
Note to all electronic scale users: If you spill a few granules of a powder onto the scale pan it will attempt to rezero itself. If I put 3 squares of paper on my Pact after a few seconds it will rezero itself and after weighing 1/10 it will drop back to zero, take the 3 papers off and put back on the scale and it again will weigh 1/10 grain.. Doesn't do that even with light pistol charges dumped into the pan at once. So don't think your scale will be exact if you spill a tiny amount of powder into the pan and then add the main charge later. Manuals tell to avoid this. Temperature inside approx. 75 degrees. thunder and rain outside with humidity of 90% outside. 4 foot fluorescent light 4 foot above the bench. Have had good performance with my Pact and would buy another immediately should it quit after about 20 years of service.

 

[GaryL]

Hornady GS-1500. Got it for ~$30 at Cabelas several years back.

I have 3 check weights I can use (there's 4th, the smallest, but it apparently escaped to the floor and I'll have to track it down). I choose weights that were in the range that it typically sees, and would not be affected by fingerprints or dust (so not too light). I picked several random objects, and put them on a high end NIST traceable calibrated scale in one of the R&D labs at work. It is often used for very small objects and will weight fingerprints.

Check Weight gr, GS-1500 gr
8.13 - 8.1
66.25 - 66.1
200.9 - 200.6

Somewhere I have written down the first time I did that, but the results were about the same. The 200gr weight might be slightly different.

 

[Dave P]

Sure, why not ...
Acculab Vicon says the copy paper weighs 0.10 gr. Pretty consistent.

 

[JerkandFlinch]

Like Otto I have the Gemini 20. Mine sees 1 piece of paper about 30% of the time. But who knows if my paper is the same as his. More importantly it tells me my 3.086gn (.200g) check weight is 3.08gn. Also it sees the 1 piece of paper when added to the check weight every time.

If anyone is interested in the Gemini 20 there is an excellent review of it on Amazon.
Next time I buy a scale I will get one that uses AC power, the Gemini has only battery power and shuts itself off automatically, this is a pain when trying to keep it warmed.

 

[armarsh]

Measured 1/4 x 1/4" square of a post-it note. It always weighs the same for me . Kernels of Varget and H4350 weigh about .02g ea.



Edited to add: Resolution is .015 grain and it cost me $400. It is a Magnetic Force Restoration type of scale that does not have load cells. It will not drift over time and will display the sample weight almost instantly.

 

[cmb3366]

I massed a .25"x.25" piece of notepad and it came out at 0.0038g, which converts to 0.0586gr. My loading scale is a Mettler AE200 analytical balance I bought at auction for $200. Resolution is .0001g, and it reacts to single flakes of powder.

Not the average reloading scale, but old lab balances are available and on the cheap if you look around.

 

[LiveLife]

So far, here are the results:

bds: FA DS-750 - .1 gr resolution, 74F, .1 gr detection of 2-3 pieces of 20 lb paper, repeatability 10x, .5 gr check weight verified ($25-$30)

Otto: Gemini-20 - .02 gr resolution, .06 gr detection of 20 lb paper, repeatability 10x, .5 gr check weight verified ($20)

Peter M. Eick: RCBS/Pact Powder Pro - .1 gr resolution, 78F, .1 gr detection of 2 pieces of 20 lb paper, .5 gr check weight verified ($150)

rcmodel: "ancient" Cabela/RCBS - Failed to detect up to 6 pieces of paper

rg1: Pact 120v - 75F, .1 gr detection of 3 pieces of printer paper, check weight verified

armarsh: A&D FX120i - .015 gr resolution, .04 gr detection of post-it note ($400)

cmb3366: Mettler AE200 - .0015 gr resolution, .058 gr detection of notepad ($200)

 

[armarsh]

BDS - I think you dropped off a zero on the Mettler AE200. (.0001g = .0015 gr.)

 

[LiveLife]

Dang decaf!

Damn the doctor, I am going to drink regular coffee after retirement!


Anyone else willing to volunteer some time for this myth busting?

We need MORE DATA!

 

[Peter M. Eick]

Do we need more data?

Basically I see a 1/4" square piece of paper is weighing about 0.05 grns. Most scales (other than Rcmodel's ancient one can detect 2 pieces with 0.1 grns precision. We have one outlier that took 3 pieces with a pact scale.

I would have drawn the conclusion that digitals in general are good to their advertised precision of 0.1 grns and called it good. The need for a balance beam with its potential to measure finer is mitigated at this point.

 

[Dave P]

We need MORE DATA!

In addition to my previous post, my scale resolves to +- .02 gr, cost was $300 I think.

 

[Reloadron]

Dang decaf!

Damn the doctor, I am going to drink regular coffee after retirement!


Anyone else willing to volunteer some time for this myth busting?

We need MORE DATA!

Forgive me for being slow ion the uptake but what myth are we trying to bust? I am missing something somewhere in all of this.

Ron

 

[LiveLife]

Here are some of the myths:

- Cheap digital scales around $20+ are not reliable and cannot be trusted. They are OK for weighing bullets but not suitable for accurate reloading tasks.

- You cannot get reliable digital scale unless you buy more expensive $100-$150+ units

 

[cfullgraf]

I have a Pact, Dillon, and the marketed by Berry Mfg. All read to the nearest 10th of a grain so I would not expect them to show any reaction to one piece of 1/4x1/4 paper.

When check weights are used, all three read correctly.

A scale the reads to the nearest hundreth grain, I would expect it to read one piece of paper.

A beam scale that reads to one tenth grain may show a change in position with one piece of paper but you can only weigh to as close as half the finest markings one the scale.

So, I also wonder what is the point.

 

[cmb3366]

In addition to my Mettler for at home use, I picked up a Hornady GS1500 for portable loading with hand dies at the range, I use it to check adjustments on the powder measure to double check myself. While I do find I need to give it time to settle down, and I frequently use check weights to ensure accuracy, this little $30 scale is fine for reloading tasks as far as I'm concerned, at least when using it as a check against a measure, not trickling powder.

The following are images of it and my Mettler with a 10gr Lyman check weight (which is itself, not perfect).

 

[Reloadron]

Here are some of the myths:

- Cheap digital scales around $20+ are not reliable and cannot be trusted. They are OK for weighing bullets but not suitable for accurate reloading tasks.

- You cannot get reliable digital scale unless you buy more expensive $100-$150+ units

Thank you and now I get what we are after.

Ron

 

[horsemen61]

Good thread thanks bds

 

[LiveLife]

So are we able to compile the data collected so far and conclude:

Since 1/4"x1/4" pieces of paper weigh .04-.06 gr (.05 gr average) and if your digital scale is able to detect and consistently read one piece or .1 gr with 2 pieces while reading accurate with check weights, then your digital scale (even the "cheaper" $20+ ones) can be trusted enough for reloading?

And in the absence of check weights, we may be able to use 1/4"x1/4" pieces of paper to verify the accuracy of beam or digital scale knowing that each piece will average .05 gr.

Any counter arguments/comments?

And feel free to post more data from your digital scales.