Digital scale drift?

Potashminer said:
Really "spinning" now - so both scales have "accuracy" capability of 0.1 grains. Set CM Lite to deliver 35.0 grains - could get a "true" weight of 34.9 to 35.1 grains delivered, within that "accuracy" range. Then, on to that Hornady beam scale - so a "light" one - true weight as 34.9 grains - could read 34.8 to 35.0 on the beam scale - its accuracy. Or a "heavy" one - true weight as 35.1 grains - could read 35.0 to 35.2 grains on that beam scale. So, set the CM Lite to 35.0 grains - within 0.1 grain accuracy on each scale, could read from 34.8 to 35.2 on the Hornady beam scale - 8 out of 10 throws did that. Very first two thrown from that CM did not.

Does not help me understand what is "drift" on a digital scale?
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I had the same RCBS system some years ago and I studied the load accuracy in some detail. At first I was using a Sartorious 2 decimal place (in grains) balance to compare the values. That was quite a good balance at the time, then I later replaced that with a lab grade Vibra 3 decimal place (in grains) balance.

I found the accuracy of the RCBS system was actually about plus or minus .2 grains on a good day. I realized there was a considerable difference between the precise number displayed on the readout, and the actual weight of the powder charge.

Its actually even worse than that since it is automated. These automated systems will get you close enough for casual shooting but just wont cut it for competitions like F Class particularly at extended ranges. (if you expect to do well anyway)

For a while I just used the RCBS to throw the powder so I could fix it in the Vibra, then eventually realized the absurdity of it and sold off the RCBS.

Now I use an old school powder thrower from RCBS and then tune the load on the Vibra. To be honest, the load variance from the thrower isn't much worse than the RCBS, but certainly faster.

I would advise anyone to forget the expensive automated gadgetry and just spend your money on a more precise balance and a set of Lyman powder scoops.

I understand that may not be what you want to hear, but the reality is that by the time you realize your one decimal place scale has drifted, you are already easily off by at least .2 grains.

At least if you have a decent 2 decimal place scale (which is actually 5 times more accurate not ten times) it will be within about .04 grains. Thats about 2 kernels of Varget.

Now the Vibra balance is about 10 times better than that at about 0.004 grains, or within about a fifth kernel of Varget, but it is quite expensive.

You can break that powder charge accuracy down to feet per second if you want... 5 kernels of Varget is about 1/10th of a grain. So if your scale is only accurate to within 0.4 grains thats about 20 kernels of Varget.

Looking at the Nosler load data for 80 grain bullets for a 223, 24 grains of Varget gets 2553 FPS and 26 grains gets 2655, so the difference is 102 FPS for a 1 grain load difference.

Multiply that times 0.4 and you get a FPS change of 40.8 FPS with a variance of 0.4 grains of powder.

You can calculate what a 40 FPS velocity spread translates to in terms of drop at the distance of your choice to determine if it matters to you.

Considering that the target is round in F Class and widest along the horizontal center, maintaining a low vertical spread is the key to holding the widest part of the scoring ring. Vertical variance tend to leak out at 1:30 with the slightest wind error.
 
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chuck nelson said:
Unless you are willing to buy a digital lab grade balance, go with a beam scale.
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I just looked through some maker's advertising - Hornady and RCBS beam scales seem rated at plus or minus 0.1 grain accuracy - so same as the digital ChargeMaster Lite. Is there a beam scale that has tighter tolerance than plus/minus 0.1 grain??
 
I just looked at the A&D FX 120i - so maker says it is plus/minus 0.02 grain - for about double the price of a Chargemaster Lite - after taxes, shipping, etc. - Amazon.ca
 
Potashminer said:
I just looked at the A&D FX 120i - so maker says it is plus/minus 0.02 grain - for about double the price of a Chargemaster Lite - after taxes, shipping, etc. - Amazon.ca
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I bought a used RCBS digital scale recently and I can have drift with it as I understand the term. I also have an RCBS beam scale. Both scales are very accurate measuring a weight or powder charge placed on them and always agree. When I throw charge and then trickle up to weight is where I get drift on the digital scale. If I throw a charge and it comes up light, say 25.8 when I am aiming for 26.0gr then I trickle up to the desired weight. If I do this several times without re-zeroing or placing the empty pan back on the digital scale then my scale tends to drift, and forget where zero actually is. The drift over 20 rounds or so can add up to a few 1/10ths. That is my experience with a couple of different scales and is easily avoided by placing the empty pan back on the scale frequently and re-zeroing if required. As far as I can determine, that is drift and it seems that it occurs when trickling powder. The drift that I have seen is always to a higher than desired charge. I think it can be avoided by placing the pan back on the platen after emptying each time. The beam scale will not do this, but I am not advocating for one over the other for accuracy. Both will measure a change of .1 gr or a few kernels of powder quite easily.
Anyway, I believe that is what is called drift and I have no idea if the automatic powder dispensers are prone to it. Since you place the empty pan back on the platen each time, they probably maintain zero quite well but that's an uneducated guess.
 
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j_san said:
Keep your cellphone away from any electronic scale. I have noticed on occasion that the two digital scales I have are effected by cellular activity.
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Autotrickler v3s and the v4s run on bluetooth.
Operator must use cellphone or tablet (or other bluetooth device) to control dispensing system.
I can have my cellphone leaning against my scale and not have it disrupt its performance.

However, I have read in other threads -that electronics that create radio waves (I changed from Florescent to LED lighting for this reason) can potential interfere with an electronic scale....that being said wonder if bluetooth creates radio waves too?

Wondering if I may have changed my shop's lighting in vein ?
 
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Munkey - is a curiosity for sure - I had read similar and did similar. However, normally my laptop sits on desk where I place my scale when reloading. Noticed that my laptop is picking up LAN signals from several neighbours. Is picking up the "Hotspot" signal from my wife's cell phone - which is inside the house, not here in garage. My guess is about "power" - how strong was the signal?? If cell phone very close, would think it could deliver more "power" - and relates to the internal shielding that may or may not be present within the scale itself. One would think newer stuff is designed for newer environment - but that is pure speculation. Not all is lost, however, I am very pleased / impressed with changeover in here from Compact Fluorescent to the LED lights - super bright, super "white" light which is good for my old eyes, I think!
 
j_san said:
That’s neat. Which make is it?
Never knew there was that sort of scale. Clearly I live under a rock lol
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Just because you can, does not mean you should.
Most scales will drift when a cell phone or cordless phone are within about 2 or 3 feet.
 
Maple57 said:
Just because you can, does not mean you should.
Most scales will drift when a cell phone or cordless phone are within about 2 or 3 feet.
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If by "drift" you mean that the display will wander away from "0.0", now into Day 3 - CM Lite has been "On" continuously - still displaying "0.0" with nothing in the pan - past 2 days continuously has been within 40 inches (1 meter) of my cell phone and 20 inches (50 cm) of my laptop, which have both been powered up continuously. They are tethered - the "HotSpot" on the iPhone is my connection to Internet. Bluetooth on both laptop and cell phone are shut off.
 
Every time I read one of these threads about digital scales and the headaches folks have with them, I'm glad I live "under a rock".

I have both fluorescent and LED lights at my reloading table , and my cell phone sits on the bench a lot of the time.

My old 5-0-5 beam scale doesn't seem the least bit put out by either. It's sensitive enough that 1 kernel of rifle powder (at most 2) is enough to move the pointer. I don't have inclination to split kernels.

I don't have enough hair left to risk pulling it out over stuff like this.

I doubt many will receive my comment in the spirit it was made in, but maybe take a step back and think about why you do this.
 
Chilly807 said:
Every time I read one of these threads about digital scales and the headaches folks have with them, I'm glad I live "under a rock".

I have both fluorescent and LED lights at my reloading table , and my cell phone sits on the bench a lot of the time.

My old 5-0-5 beam scale doesn't seem the least bit put out by either. It's sensitive enough that 1 kernel of rifle powder (at most 2) is enough to move the pointer. I don't have inclination to split kernels.

I don't have enough hair left to risk pulling it out over stuff like this.

I doubt many will receive my comment in the spirit it was made in, but maybe take a step back and think about why you do this.
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Your comments make a bunch of sense.
 
Chilly807 said:
Every time I read one of these threads about digital scales and the headaches folks have with them, I'm glad I live "under a rock".

I have both fluorescent and LED lights at my reloading table , and my cell phone sits on the bench a lot of the time.

My old 5-0-5 beam scale doesn't seem the least bit put out by either. It's sensitive enough that 1 kernel of rifle powder (at most 2) is enough to move the pointer. I don't have inclination to split kernels.

I don't have enough hair left to risk pulling it out over stuff like this.

I doubt many will receive my comment in the spirit it was made in, but maybe take a step back and think about why you do this.
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I agree with your experience - is about same as mine with a balance beam Hornady scale. My original question on this thread was what is "drift" on an electronic scale and how would the user know that it is happening? - from your post, I suspect that you do not know, either?

So far, from replies on this thread, I now think that "drift" is happening when the user sees the value displayed on the scale, start to change, from one value to another, although the load placed on the scale pan has not changed. Lots of reasons have been offered for why false values come to be displayed.

The thread may have drifted off to include "accuracy" - your 5-0-5 RCBS scale is "accurate" to plus or minus 0.1 grains. When the pointer reads "0" that means you are within 0.1 grains of what you asked for - up to 0.1 grains light or 0.1 grains heavy - that is what the accuracy rating for your scale means - I think. The readings that you get are not more or less "accurate" or "correct" than what anyone else gets from a scale of any type that has 0.1 grains "accuracy".
 
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Chilly807 said:
Every time I read one of these threads about digital scales and the headaches folks have with them, I'm glad I live "under a rock".

I have both fluorescent and LED lights at my reloading table , and my cell phone sits on the bench a lot of the time.

My old 5-0-5 beam scale doesn't seem the least bit put out by either. It's sensitive enough that 1 kernel of rifle powder (at most 2) is enough to move the pointer. I don't have inclination to split kernels.

I don't have enough hair left to risk pulling it out over stuff like this.

I doubt many will receive my comment in the spirit it was made in, but maybe take a step back and think about why you do this.
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I use a RCBS 10-10 which was tuned - it is spot on. I have my furnace about 10 feet away my iPad streaming either a Youtube video or watching Newsmax while reloading less than a foot away from my scale. It's a bit old school don't worry about drifting. Your comment makes perfect sense +1
 
Potashminer said:
Your first statement - seeing the display slowly change - is what I see on the Lyman DPS 3 - as if the computer is changing its mind about what weight is on that pan - shows a value on the display, then that value that is displayed changes over several minutes... The weight in the pan did not change, but the display does. Maybe the change in the display is what people are calling "drift"?
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I have that from time to time with a cheap MTM scale, it'll drift after I trickle a few granules of powder in. 50.0 grains will decide it's actually 50.1 grains after 5 or 10 seconds. I just pull the powder pan off the scale and remeasure, if it still says 50.0 initially the charge goes in the case. Seems to work but it's definitely unnerving with maximum charges.
 
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