Revisited - Myth Busting Digital Scales

[LiveLife]

https://www.thehighroad.org/index.p...tal-scale-accuracy.759750/page-4#post-9591790

In the "THR myth confirmation/busting - digital scale accuracy" thread, with the help of THR members, we confirmed digital scales (even cheap $20-$30 ones) could be accurate enough for reloading with a set of check weights and we even tested the sensitivity and accuracy by using 1/4"x1/4" pieces of 20 lb copy paper along with .5 grain check weight and got the following results:


bds: American Weigh Scales Gemini-20 - .02 gr resolution, .06 gr detection of 1 piece of 20 lb paper, .5 gr check weight verified ($23)

bds: Frankford Arsenal DS-750 - .1 gr resolution, .1 gr detection of 2-3 pieces of 20 lb paper, .5 gr check weight verified ($25-$30)

Otto: American Weigh Scales Gemini-20 - .02 gr resolution, .06 gr detection of 20 lb paper, .5 gr check weight verified ($20)

Peter M. Eick: RCBS/Pact Powder Pro - .1 gr resolution, .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 - .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)

RedHawk357Mag: Acculab VIC123 - .015 gr resolution, .04 gr detection of 20 lb paper, .5 gr check weight verified ($240)

Jesse Heywood: RCBS Range Master 750 - .1 gr resolution, Failed to detect up to 10 pieces of 20 lb paper ($110)


Since then, there have been many new digital scales that became available and once again, I ask the THR community help verify sensitivity and accuracy of scales so we can add to the list which can be referenced by other THR members/guests shopping for digital scales.

- Use new/clean 20 lb sheets of copy/print paper
- Cut 1/4" x 1/4" pieces using ruler/calipers and handle with tweezers to prevent contamination by finger oils (Each ream of 500 sheets should weigh 5 lbs and each 1/4"x1/4" piece "should" weigh around .0468 gr)
- Level bench/counter surface
- You may need to use cover or clear bowl to block air movement
- Remove questionable sources of interference or noise (magnets, cellphone, etc.)
- Use fresh batteries or allow the AC scales to warm up
- After calibrating the scale and zero/tare, place one piece of paper and check displayed weight
- If scale won't detect one piece of paper, place additional pieces until 1.0 grain reading is displayed
- If scale won't detect several pieces of paper, place a check weight and repeat the test

Thank you in advance.

If there are tests you want to "myth bust", we can certainly conduct them in this thread.

 

[jmorris]

May be worth doing your test somewhere above zero.

I know for a fact that there are scales that will auto zero themselves under a certain weight. That would make you think they can't "detect" what you are putting onto them.
The RCBS 1500 does excatly that video below. Might be why the results in the tests above look so bad for thier scales.

 

[LiveLife]

Good point.

If the digital scale has trouble detecting several pieces of paper, you can place a check weight and repeat the test.

I will revise the OP.

 

[Rule3]

Is there a summary of all the scales from the original post (6 pages to comb through)??

 

[LiveLife]

Listing of scale results in post #1 is the summary of scales tested but the list is short and I am hoping we get more comprehensive list of scales on this thread.

 

[LiveLife]

I added few more lines to testing procedures and revised the OP:

- Use new/clean 20 lb sheets of copy/print paper
- Cut 1/4" x 1/4" pieces using ruler/calipers and handle with tweezers to prevent contamination by finger oils (Each ream of 500 sheets should weigh 5 lbs and each 1/4"x1/4" piece "should" weigh around .0468 gr)
- Level bench/counter surface
- You may need to use cover or clear bowl to block air movement
- Remove questionable sources of interference or noise (magnets, cellphone, etc.)
- Use fresh batteries or allow the AC scales to warm up
- After calibrating the scale and zero/tare, place one piece of paper and check displayed weight
- If scale won't detect one piece of paper, place additional pieces until 1.0 grain reading is displayed
- If scale won't detect several pieces of paper, place a check weight and repeat the test

 

[spitballer]

Great info here. I've been using an old Ohaus that I bought years ago to weigh aquarium chemistry and it's remarkably accurate if used with the right check weights, as suggested in this thread.

 

[peterk1234]

How about checking against your beam scale? I take a powder charge, place it on the digital scale then verify on the beam scale. Am I being too simplistic? I find that my digital scale is right on many times, but on average, gives me .1 grains higher reading than my beam.

 

[LiveLife]

I guess we could use some baseline reference.

I placed two 1/4"x1/4" 20 lb copy paper pieces on the Ohaus 10-10 and got the following reading. Since each vertical line indicates .2 gr, I say the pointer looks to be around .1 gr.

- Ohaus 10-10 - When 10 mg (.154 gr) check weight from Ohaus ASTM Class 6 set was placed, I got the following reading below. Looks to me the pointer is between .1 and .2 gr.
- Gemini-20 digital scale displayed 10 mg and oscillated between .14 and .16 gr (probably from .02 gr resolution).
- FA DS-750 digital scale displayed 0.0 mg and flashed .2 gr on and off. When I placed 10 mg weight with 20 mg weight, display showed .5 gr. When I removed the 10 mg weight, the display showed .3 gr.

- Ohaus 10-10 - When 20 mg (.308 gr) check weight was placed, got the following reading below. Looks like slightly more than .3 gr.
- Gemini-20 digital scale displayed 20 mg and .30 gr.
- FA DS-750 digital scale displayed 20 mg and .3 gr.

 

[Dudedog]

Those little GEM 20s are surprising for the price. I have a 5-0-5 which I rarely use, the GEM 20 for checking really close.
Most of the time I just use the Frankford DS750. I would note my DS750 gets a little confused when the batteries are about to go bad.
If you would like I can cut up some copy paper and check my DS750 and GEM20 but I am guessing the results will be about what was found earlier.

 

[jmorris]

I missed the beam scale post but they can be quite sensitive too if you can detect the slightest movement of the beam. Like the 5-0-5 at the very end of the video I posted in #2 and this 10-10.