Drifting Electronic Scales

[wkdickinson]

Because this thread started out with a question about a Gempro, here is my experience. I've had a GP500 for maybe 10 years and have no issues with drift. My reloading area is in my basement, has all "tube-style" LED lighting and my power is filtered through a very good Monster power strip. My RCBS Chargemaster is right next to the GP and it periodically drifts terribly.

 

[boltman13]

My Autotrickler Gen 3 with the A&D Fx120i and a Trip Lite power conditioner runs like a champ. I have used 2 different Lyman systems with generally good results in the past but they are slower and less accurate. The results show up on paper at 600 and 1,000 yds. For hunting ammunition I doubt it would make any difference at 300 or fewer yards to the hunter or animal. I used a GemPro 250 and got more precise loads than either Lyman but the time and aggravation were off putting. Most people consider the Chargemaster superior to the Lyman or Hornady systems, but I have no experience with one. Beam Scales can certainly give fairly accurate consistent charges, and tuned ones even more so. I value accuracy first and speed second. With my system I get both. It's your time and your money so best of luck which ever way you go. Don't forget most short range benchrest shooters just use a powder thrower into the case and don't weigh and shoot bughole groups, but their throwers are not cheep.

 

[Whisky Tahoe Foxtrot]

Electrical isolation, zero wind including air vents, and static reduction all help along with properly warmed up electronics. One additional factor to consider is the technology used in a scale. There are two primary types: The strain gauge and magnetic force restoration with the latter having less issues with the zero drifting.

Frequent calibration especially through temperature shifts is important. My reloading bench in the garage can be low 50s in the morning and high sixties by the afternoon. Worse in summer.

 

[ronemus]

I worked daily with precision analytical balances (I'm a research chemist and systems engineer) that offer the precision and resolution we're looking for here, but those instruments cost thousands to tens of thousands of dollars. To reach a price we're willing to pay, some corners must be cut (vendors won't line up to sell to us below cost). Unfortunately, the instruction manuals accompanying our scales generally aren't very good at spelling out the steps necessary to have then operate to our satisfaction.

For stable zeros it's necessary to warm up for at least a few hours (they're generally left on continuously to avoid drift) and keep the room temperature fairly constant (within a few degrees).

Inexpensive scales such as these are commonly bothered by power line noise and transients, but those can be eliminated by using a filtered power strip; I use and recommend a Tripp-Lite Isobar.

Static electricity can easily shift readings by a few grains, so it pays to wipe down all plastic surfaces with an antistatic such as a drier sheet. Don't wear nylon or other static-prone fabrics when working with the scale. A humidifier set to maintain 35% RH will help a lot.

It is necessary to isolate the scale from drafts and vibrations. Laboratory scales with this sort of resolution generally have a housing around the pan with sliding doors for access and vibration isolators in the feet. An air current that's not even perceptible can easily shift readings at the level of precision we're looking for, but opening and closing a door is a nuisance when you're trying to up the pace. I use a carboard file box (intended for archival document storage) with one end cut out placed over the scale. The side goes down so the box can be removed for filling with powder, etc. without disturbing the scale. I leave off the top (now facing forward) so I can work my AutoThrow/AutoTrickler and A&D fX-120i scale; I remove only the righ side draft shield from the scale and place the AutoTrickler at the back so there is plenty of room to get the pan in and out. With the bench closing the bottom and the box closing three sides and the top, air currents have a hard time getting to the scale.

Vibrations are another problem - you don't want to have heavy equipment operating nearby, or foot traffic on a residential floor. You can make a vibration isolator by putting a heavy plate (Steel, stone, concrete, etc. - I use a granite surface plate bought on sale from Enco) on a slab of soft foam, but it may not be effective; really good vibration isolators are expensive.

 

[D-4297]

Been using the old Gem-Pro 250 for about five years now . Had some drifting issues with it initially , and went into the instruction manual to figure out what "I" hadn't done correctly .
I purchased a filtered power strip at a computer place .
I added two of the in-line filter pieces on the power cord .
I wipe the pan about once a week with a dryer sheet .
And believe it or not ; it stays plugged in , and turned on 24 / 7 , 365 .
And I re-zero about every five or so loads .
No drifting , no variations . Checked it against the A120i and it is just as consistent . I hand trickle to finish .
Sometimes you just have to take extra care when playing with electronic toys . No matter the price .

 

[ronemus]

Scales by GemPro, RCBS, Redding, Dillon, etc. are load-cell balances and inherently temperature-sensitive. The A&D fX-120i is the least-expensive magnetic force restoration balance I know of, and this technology is inherently insensitive to temperature; it's the same technology used in precision laboratory balances costing thousands of dollars. It's not as good as the lab-grade balances (corners must be cut to make the price point), but it's a lot better than the load-cell balances.

 

[hambone1971]

My GemPro250 works great if I turn it on an hour before I intend to use it.
Still have to zero now and then but that's ok for the .02 grain resolution I get.
Also having a simple check weight like a bullet to keep check on it helps.
Doesn't matter what your bullet weighs as long as it always weighs the same.
Someone ask is this accuracy really necessary, depends, long range yep it helps,
peace of mind that your as good as you can be with consistent powder charges yep.
jmo HB

 

[tovaert]

Depending on the size of the charge you are throwing, and given that powder absorbs water vapor, precision to 0.01 grains can be negated by humidity changes in the reloading room. Measuring powder volume (ideal) is much more expensive.

 

[Timon]

I think the main reason for the electronic scales is that all of the automatic powder dispensers use an electronic scale. My 505 works great to, and I use it to set up my thrower for ball powder charges. So unfortunately if you want to use an auto powder dispenser, you might have to deal with

 

[Timon]

Thank you all for the absolutely overwhelming amount of information. I am going to work with the Gempro that I have and see if I can work out the bugs. I think just for the sake of trying, I am going to run the Gempro off of batteries to see if that makes any difference. I would think that the battery power should be clean. If I’m wrong please tell me. Of course I will do this after wiping everything down with a dryer sheet.

 

[Timon]

Scales by GemPro, RCBS, Redding, Dillon, etc. are load-cell balances and inherently temperature-sensitive. The A&D fX-120i is the least-expensive magnetic force restoration balance I know of, and this technology is inherently insensitive to temperature; it's the same technology used in precision laboratory balances costing thousands of dollars. It's not as good as the lab-grade balances (corners must be cut to make the price point), but it's a lot better than the load-cell balances.

Would most of the load cell type scales all be basically the same then, or could one be better than another?

 

[Turbulent Turtle]

Would most of the load cell type scales all be basically the same then, or could one be better than another?

It's the nature of the beast. There are certainly better ones but they all suffer from the same design concept problem and they will all drift at some point, especially during a long loading session. The Gempros are pieces of trash but luckily the company that bought Gempro was kind enough to refund my money in full 5 years after I bought that Gempro.

The A&D FX-120 is a different concept and as was explained earlier, it is a magnetic force restoration design, which is what the high end balances use. When you plug in the A&D, you can feel the current flowing through it. Just put you hand on the surface beneath the platen and you can feel it.

The principle here is that it requires X amount of power to hold the platen at an exact location. When you load the pan on the platen, the balance has to increase the power to keep the platen at the proper location. The difference in power output is used to calculate the weight on the pan and its contents.

Such balances are VERY accurate and reliable as there is no strain to measure and they are not affected by temperature. If you puch on the platen just a bit and release it, you get an instant and accurate reading. It also detects very quickly any change in the contents.

It does cost more because of the more intricate and costly design and it is very sensitive to air currents. I put mine on a table and surround the whole outfit (with the Autotrickler and Autothrow with a large trifold foam board to deflect any air currents. It is not sensitive to cell phones. I use my smartphone to communicate with the trickler device via Bluetooth, and while I certainly use a surge protector, it does not seem to be affected by household current with its vagaries. Remember that the power brick for that device converts the AC to DC before it even gets to the balance.

Trying to make a Gempro or any other strain guage (load cell) balance perform like an MFR balance is an exercise in futility. I found that out years ago, switched and never looked back.

 

[INTJ]

The scales I have used in order of precision, worst to best:

1. RCBS Chargemaster. About .2 grain accuracy

2. RCBS 10-10. Accuracy .09 grains as verified on a Sartorius Entris 124-1

3. A&D FXI-120. Accuracy .02 grains, or about one kernel

4 Sartorius Entris 124-1. Accuracy .001 grains, 20 times more than the A&D.

I suppose when I say accuracy I guess I am really saying if the scale is calibrated perfectly that is the resolution.

The Chargemaster is fine for many things, but high precision in small cases isn't it's best use.

The 10-10 is fine for most things

The A&D FXI-120 is the sweet spot for charging powder

The Sartorius is okay for powder, though it's sensitivity slows me down, but great for weighing primers and cases. The larger wind block makes it easy to put stuff in and out. I only have a Sartorius because I couldn't find an A&D three years ago when I needed to quickly load 300 perfect rounds.

 

[Turbulent Turtle]

@INTJ, I like your list and I think you've got it right: for handloading purposes the A&D is indeed the sweet spot.

The issue I had with my Gempro was indeed the drifting. This really hit me about 5 years ago (or maybe 6 now) when I had a long loading session in preparation for the US Nationals. In one day I loaded 400 rounds using a combination of Chargemaster, Gempro and Omega trickler. The Chargemaster would dispense a load that was 1 grain short of my target load. I would transfer the powder from the CM's pan to the one on the Gempro and put it back in the CM to dsipense the next one. While the CM was doing its thing, I used the Omega trickler to trickle up to the desired weight on the Gempro. When the target weight was reached, I would dump the load in a prepared case and start the cycle over again.

It was horrible.

This is a lot of handling and minute operations that require constant attention. Beyond the drugery of the operation, the Gempro would start going up and down at irregular intervals. It would do fine at the beginning but after say 30-40 rounds, it would start acting up. I would stop, rezero the device and if it still did it I would recalibrate it with a weight. Then it would go for a while longer and start doing the same thing again. I was so glad when I finished the 400 rounds.

When I returned from the Nationals, I bought an A&D and retired the Gempro. The A&D worked out great. No drifting, ever, but it was still a two balance operation with an Omega trickler. Then Adam released the Autotrickler. I retired the CM and the Omega and the rest is history.