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  #51  
Old 11-08-2019, 12:14 PM
1911_Kid 1911_Kid is offline
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Here's my test.

cal scale using the 50g weight.
set scale to mg measure (display 0-50,000max)
then put on the 20g weight.
then added a tiny piece of foam to the top of the 20g.
scale consistently adds 1-3mg every time i put the foam piece on top of 20g.

but, i try to measure just the foam piece, scale stays at zero.

I not sure why this is. I do recall from instrumentation classes (way back when) that a measuring device should be used in some range between min and max of device. My digi spec says 0-50g, but for accuracy and consistency reasons I should stay between say 10mg and 40,990mg.

If i wanted to measure stuff that was in range of 5-50mg, then don't buy a scale that has a range of 0-50g, something like a 0-150mg is better.

We often overlook accuracy and consistency across the range. These tests should be done at intervals, say every 10mg. You will be surprised to see it's not a flat curve across the range.

Last edited by 1911_Kid; 11-08-2019 at 01:55 PM.
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  #52  
Old 11-08-2019, 12:19 PM
1911_Kid 1911_Kid is offline
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Quote:
Originally Posted by BC17A View Post
Best way I found to sleep at night is to just make a set of known weights in the ranges we're loading to. I made a simple set of weights from some brass ranging from 1.5gn up to 5gn, in .5gn increments, and use them to verify my powder drop to scale accuracy before each loading session. Some reloaders feel the need to have the best and most expensive equipment, and that's fine, but it really isn't necessary.
That is for consistency only, it does not tell you the actual weight unless your scale has been calibrated with a known good weight, and even after that, actual weight will be within the accuracy spec of the scale, like ±5mg, etc. Granted ±5mg is only about 0.1gr, which should be negligible for everyone.

So do you weigh the ring, tare it, then fill back to zero? I have yet to see what my cheapo scale does using this method.

But having a few $7 weights that come with a cert paper, should be an ok choice to make sure the scale is ok.

Last edited by 1911_Kid; 11-08-2019 at 12:23 PM.
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  #53  
Old 11-08-2019, 02:31 PM
MKeith2 MKeith2 is offline
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Powder scale

I have two. An RCBS digital and the Hornady Lock-N-Load Bench Digital Powder Scale 1500 Grain Capacity. I have had very good results with the Hornady. It doesn't drift and stays zeroed. Not so much with the RCBS.
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  #54  
Old 11-08-2019, 04:28 PM
Twoboxer Twoboxer is offline
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Quote:
Originally Posted by 1911_Kid View Post
Here's my test.

cal scale using the 50g weight.
set scale to mg measure (display 0-50,000max)
then put on the 20g weight.
then added a tiny piece of foam to the top of the 20g.
scale consistently adds 1-3mg every time i put the foam piece on top of 20g.

but, i try to measure just the foam piece, scale stays at zero.

I not sure why this is.. . .
My own conclusion from similar tests a while back was "the scale's programming".

One of my scales, a <$20 Hornady 1500, would perform exactly the same as yours did, only ignoring the extra weight when starting at "0".

The next digital, a $125 Gempro 250, wouldn't recognize a kernel of powder (ie, a small piece of foam) either at "0" or after adding a kernel to some weight already in the pan. This scale lost zero a bit less frequently and fluttered a little less in my reloading room than the Hornady, or my Pact dispenser/scale, or my CM 1500.

My hypothesis was some programming is done in certain scales to ignore small "weight changes" under certain conditions in an effort to suppress fluttering due to noise.
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  #55  
Old 11-08-2019, 06:06 PM
1911_Kid 1911_Kid is offline
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I not sure about programming in a differential "ignore". Perhaps maybe.

My cheapo scale paper says ±5mg. So if I start at 20,000mg and add 4mg the reading of the differential can still have error of ±5mg. In other words, the scale says "i recognize a diff here, let me measure it" but the actual "measure" part can still carry error.

As example, real actual weight of 20,000mg and 2mg
So in real true measure the weight combined is 20,002mg

But lets start with 20,000mg on the scale, then add the 2mg.
The expectation after adding the 2mg is that the scale should display the weight in the range of 19,997-20,007mg, because i need to apply ±5mg tolerance to the new reading of actual weight. But if i started with 20,000mg how could the weight go down when adding 2mg? Simple, error of the scale, and in my scale it says ±5mg.

What i do find interesting with this little scale i got is, put weight on, tare it, remove weight, the display will add the minus sign, so it can display negative. Ok, i start at zero and add a ~3mg weight, with the error applied the scale should show me something in the range of -2mg to 8mg. But it didn't. This leads me to believe that the paperwork is missing a pertinent spec, the real operating range, like what we saw on that 1500. Perhaps my little cheapo scale is not a 0-50g scale, perhaps it's more like a 0.006-49.996g scale. No way to know.

With that 1500 stating 2-300gr as the operating range, perhaps it is coded to display zero+error when the actual weight is less than 2gr? Dunno, would need to ask that manufacturer.

tare can be a kluge too because that relies on differential in the opposite direction. With mechanics, pushing down with a weight is not the same as allowing the tool to "spring" back up on it's own after applying a force.
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  #56  
Old 11-08-2019, 07:06 PM
jmorris jmorris is offline
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Quote:
almost all digi scales, even the cheap ones, can detect one kernel, but simply cannot display it. It would not be difficult to add a "detect light" to a digi scale where one kernel could be detected, but the weight of that is way under the accuracy spec, like my digi says ±5mg (near 0.1gr).
The difficult part is having a load cell that can detect very small changes in mass, while being strong enough for heavier loads, then programming it so it is not always just searching, rather reads with stability. It’s easy to make the display read to .0000000 grains but useless if the numbers never stop changing.

I don’t know everything there is to know about the subject but I have dabbled a bit on a device that can sort cases to the tenth (.1) of a grain. That taught me that it’s not as easy as it looks.

https://www.youtube.com/watch?v=1V_Hm3oqlO4

Quote:
In that video the kernels were also dropped into the pan, which is enough force to cause the digi sensor to react and then settle down to zero.

But will ask, what was the actual weight of those few kernels? If they were less than 2gr then the results of the testing don't mean much, the scale spec says 2-300gr
A single kernel of 3031 I was using weighs around .02 grains. The important thing to walk away with is the fact that the scales can’t resolve that amount. Add a single kernel or even a couple on any charge and it might not even change the reading. Also the fact they are constantly self zeroing to hide the fact that they drift over time. Why most laboratory equipment manuals will tell you to turn them on long before you use them to get to operating temperature before calibration and zero.

Quote:
And yes, totally agree, apples-to-apples only if you are measuring withing the spec of the scale, which is 2-300gr. You trying to measure 0.2gr is apples-to-oranges for that scale.
Ok, try this with your digital scale. Put a 250gn check weight on it and see if it can detect when you add a single kernel to it.

Like this.

https://www.youtube.com/watch?v=yvF6WJs1zyY

If it can’t, how many before it recognizes that the mass has changed enough to have it read differently?

Last edited by jmorris; 11-08-2019 at 07:13 PM.
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  #57  
Old 11-08-2019, 07:39 PM
1911_Kid 1911_Kid is offline
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Originally Posted by jmorris View Post
Ok, try this with your digital scale. Put a 250gn check weight on it and see if it can detect when you add a single kernel to it.

Like this.

https://www.youtube.com/watch?v=yvF6WJs1zyY

If it can’t, how many before it recognizes that the mass has changed enough to have it read differently?
0.1gr = 6.48mg
0.01gr = 0.648mg
0.02gr = 1.296mg

Setting the scale to "gr" measure which only has to 0.1 resolution and trying to measure 0.02gr (one kernel) makes no sense. You at least have to get into a resolution that can display what you are after. The sensor may recognize one kernel, simply cannot display it. And if the 1500 started with 250gr weight and from there you started adding kernels, sure, expect to see no change until the # of kernels added is at least 0.1gr, because that's the smallest resolution the display has. "gr" scale to 0.1 resolution is not the right measure for weighing weights less than 0.1gr. Anything close to 1mg (kernel size) the scale has to be way better, with accuracy tolerance near +-0.5mg or better.

But I did that test using a tiny foam piece that has real weight somewhere in the 1-3mg range. Adding that to an existing 20g weight my scale did keep adding to the display, never subtracted as the tolerance allows (+- 5mg). However, when trying to just weight the foam piece by itself the scale stayed at zero.
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  #58  
Old 11-09-2019, 12:04 AM
BC17A BC17A is offline
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Quote:
Originally Posted by 1911_Kid View Post
That is for consistency only, it does not tell you the actual weight unless your scale has been calibrated with a known good weight, and even after that, actual weight will be within the accuracy spec of the scale, like ±5mg, etc. Granted ±5mg is only about 0.1gr, which should be negligible for everyone.

So do you weigh the ring, tare it, then fill back to zero? I have yet to see what my cheapo scale does using this method.

But having a few $7 weights that come with a cert paper, should be an ok choice to make sure the scale is ok.
I first verify the accuracy of the scale within a particular range before running a batch on the press. So, say I'm reloading 380 auto with 4.2gn of powder, I'll use the 4gn ring to verify the scale actually reads 4 grains. Next I'll set an empty case along with the 4gn ring on the scale, zero(tare) the scale, then charge the case on the press and weigh it again without the ring. As long as It reads 0.1gn to 0.2 it's G2G and I'll start loading away.

Last edited by BC17A; 11-09-2019 at 04:51 PM.
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  #59  
Old 11-09-2019, 03:48 AM
jmorris jmorris is offline
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Quote:
Setting the scale to "gr" measure which only has to 0.1 resolution and trying to measure 0.02gr (one kernel) makes no sense. You at least have to get into a resolution that can display
I think you are getting the point.

On your digital, that is correct. On the beam, you can detect the same mass to the kernel, or resolve the mass that accurately and the digital cannot.

That said, there are no numbers on the scale that will tell you the value despite how close they are to one another.
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  #60  
Old 11-09-2019, 06:48 AM
GWB GWB is offline
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If you take the good ole stand by 505 and add kernels you will see the beam actually moving each time though be it very slight . I just do not understand the thought process of using a low end scale for something so important to your outcome. I understand it can be done with certain loads and not affect much when your staying in the safe zone especially pistol . But my opinion is accuracy especially in rifle depends on consistency all across the board, powder weight being a main factor . Even high end electronic scales have a slight degree of variation but to a lot less degree. In the early days I loaded 1000s of pistol plinkers with a low end electronic scale and never had a problem but over time I learned the importance of powder weight and could afford better equipment so to me its money well spent.
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  #61  
Old 11-09-2019, 10:00 AM
Nitro.45 Nitro.45 is offline
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Yeah, I’m goin’ with #58.
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  #62  
Old 11-10-2019, 09:12 AM
dsonyay dsonyay is offline
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I have two scales.. Dillon Beam Scale (made by Ohaus) and a cheap Hornady digital scale. I let the digital scale warm up about 10 minutes, zero before each load and it's consistently repeatable. I even verify the reading to my dillon beam scale.

the hornady scale comes with a 10 gram check weight as well.

Key to repeatability is to let it warn up. I also do a calibration test after warm up. That scale cost me about 35 bucks. Not bad at all
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  #63  
Old 11-10-2019, 09:51 AM
Nitro.45 Nitro.45 is offline
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As mentioned before, some environments and scales will work perfectly fine. MANY, however do not. Flutter caused by electrical interference and other outside influence is a real thing. No one is saying that none of them work satisfactorily for weighing powder. Too many folks have voiced their disgust in the past and is the reason I choose not to use one. I still find it humorous that digital scale aficionados are always compelled to verify accuracy by using a beam. What’s the point? Especially if you are loading on a progressive.
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  #64  
Old 11-10-2019, 12:58 PM
jmorris jmorris is offline
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What’s the point? Especially if you are loading on a progressive.
Yeah, like I said in #48, if you are throwing volume charges, that’s perfectly fine for most uses and expectations, it really doesn’t matter if you have a scale that can repeat any better than the volume throw.

It’s not like manufacturers use weighed charges..
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  #65  
Old 11-10-2019, 01:37 PM
1911_Kid 1911_Kid is offline
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Is there any warming up period for a small digi that runs off of two AAA batts?

If you really wanted a stable scale, use it inside a temp controlled box, this way there is minimal heat flow in or out of the scale.
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  #66  
Old 11-10-2019, 03:13 PM
flechero flechero is offline
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Originally Posted by Nitro.45 View Post
I still find it humorous that digital scale aficionados are always compelled to verify accuracy by using a beam. What’s the point? Especially if you are loading on a progressive.
No kidding, for me it's faster and more accurate to just use the beam. If you leave it set at the desired charge weight, it's not any slower than waiting for the digi to settle. I'm adjusting the powder thrower to the scale, not the scale to the throw... so there is no advantage to the digi. Either it balances or it doesn't... the adjustment is on the press.
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  #67  
Old 11-10-2019, 04:08 PM
brickeyee brickeyee is offline
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Digital scales are NOT 'on-off' scales.
They always require some time to get the temperature 'correct' and staying constant.

It is not just that moving air affects the pain, but that it also alters the temperature of the electronics.

An enclosure that contains the scale and prevents air currents over it is really required.

Most of the better real lab grade scales have a complete enclosure.

Typical scale electronics depend on the accuracy and stability of a crystal oscillator.

We want absolute measurements, so radiometric circuits can be a PITA to develop.
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  #68  
Old 11-10-2019, 06:15 PM
jmorris jmorris is offline
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It is not just that moving air affects the pain, but that it also alters the temperature of the electronics.
And the generally aluminum strain gauge inside the enclosure.
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  #69  
Old 11-11-2019, 07:22 AM
Nitro.45 Nitro.45 is offline
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Temp is another negative point for the digital. There are many of us that load in a temp controlled third bedroom or basement. There are also many that load in their garage or shed. A 2 cell AAA scale would be fun to watch as the garage heater gets fired up and the temp rises from zero to 60. As Mr Morris mentions, most strain gauges are aluminum. They do a pretty good job of thermal conductivity. It would be interesting to watch the reading of a 5 grn weight from 30 degrees up to 70. This is not a hypothetical scenario. I know lots of guys that load in “out buildings” that they have to heat up.
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  #70  
Old 11-11-2019, 08:16 AM
jmorris jmorris is offline
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It would be interesting to watch the reading of a 5 grn weight from 30 degrees up to 70.
That is one reason RCBS added the “feature” where there scale is constantly changing itself. So the owners say “mine is steady as a rock”, despite the fact they have no idea what it’s really doing.

You can open them up and get the model number off the load cell and download the data sheet though. It will tell you everything you need to kno in that respect.

Have the sheet for the one used in the charge master 150o’s but didn’t see it with a quick google search. An email to the mfg. would get it pretty quick though.

http://www.hzloadcell.com/pid1148626...lery-scale.htm

Even a lab balance manual will tell you to leave it on for at least a half hour and they are often used in climate controlled rooms. The unit itself creates heat that will change the values output from the load cell. The term “creep” is the one they use when referring to values changing on their own, under identical conditions. Generally given in a value/time way.
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Last edited by jmorris; 11-11-2019 at 09:10 AM.
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  #71  
Old 11-12-2019, 07:27 AM
Nitro.45 Nitro.45 is offline
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Hmmmmm, seems like affordable technology isn’t all it’s cracked up to be.
Knife edges and agate’s do not need to be “warmed up”!
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  #72  
Old 11-12-2019, 10:13 AM
jmorris jmorris is offline
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There are pros and cons to all of them.
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  #73  
Old 11-12-2019, 12:22 PM
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Tom Freeman Tom Freeman is offline
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Single kernel repeatable accuracy isnt cheap.

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  #74  
Old 11-12-2019, 01:00 PM
1911_Kid 1911_Kid is offline
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Originally Posted by Tom Freeman View Post
Single kernel repeatable accuracy isnt cheap.
Kernels are ~0.02gr? That's about 1.3mg. So for that you need accuracy down near ±0.25mg from a digi scale.

Yep, they are not cheap.
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  #75  
Old 11-12-2019, 01:38 PM
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Quote:
Originally Posted by jmorris View Post
I think you are getting the point.

On your digital, that is correct. On the beam, you can detect the same mass to the kernel, or resolve the mass that accurately and the digital cannot.

That said, there are no numbers on the scale that will tell you the value despite how close they are to one another.



This whole thread is nuts. If you're loading on a single stage, and using a balance beam scale, you are already as accurate as you can get or need to be assuming you are weighing each charge.



The determining factor is what is the tolerance of your powder measure if you're using a progressive that auto dumps the charge or individually drops a charge from a separately mounted measure. If the measure is only capable of +- .1 gr then you don't need a scale that is any more accurate than that. That's why they make $30 electronic scales that are accurate to +- .1 gr.


There isn't a cartridge out there that will be adversely affected by a one tenth grain variance. There is more variation than that in other parts of the system. Even benchrest shooters don't obsess over .1 gr like that. Many of them I've met even use progressive loaders to make their ammo, using the auto powder dump on their press to drop charges.
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