Technique for inexpensive digital scale

[BoydAllen]

If you are using the scale as a tool to learn what measure technique works the best for your measure and a particular powder, after tareing with the empty pan and verifying your measure setting, tare the scale with nothing on the platen, and then weigh the pan with a charge in it and note that weight. It has been my observation that even though the scale reads zero it can be lying a bit. By working with the total weight of the charge and pan you can pull the charged pan, tare the empty scale and reweigh to see if the issue is the charge weight, or a scale issue, that tareing has resolved.

 

[6Creed73]

I always measure my charges with the pan weight included...even the higher quality scales will work better like this.

What I do is zero the pan to get my initial charge weight only. So if I'm shooting for 40.8 gr, I will zero the pan and trickle to 40.8. Then I'll remove it, zero the scale, put a different pan on the scale, zero that one and pour the powder on the second pan to confirm my charge weight.

Lastly, I zero out the scale again and re-weigh the charge with the pan...this is now my charge weight for the rest of my loads. Also, if the scale's native unit is grams, I'll change to measuring in grams instead of grains so it doesn't have to convert.

The scale will be more consistent without the need to keep up with the negative weight of the pan.

 

[RegionRat]

Different types of scales have different methods based on the electronics.

A simple strain gage unit uses a different method than a force-rebalance type and this offers the designers a different opportunity to add features that help with zero stability and temperature compensation.

For example, if your scale has an auto-null, the tare weight value of the pan is something to watch over the session to see if the scale is applying different values to account for drift.

Checking the zero and the calibration value (null & gain) now and then also teaches us what to expect and how often to watch. Another thing that helps, is to keep a thermometer nearby to make sure the conditions in the shop don't drift quickly as heaters or AC units drift during the day. YMMV

 

[ShtrRdy]

I always measure my charges with the pan weight included...even the higher quality scales will work better like this.

What I do is zero the pan to get my initial charge weight only. So if I'm shooting for 40.8 gr, I will zero the pan and trickle to 40.8. Then I'll remove it, zero the scale, put a different pan on the scale, zero that one and pour the powder on the second pan to confirm my charge weight.

Lastly, I zero out the scale again and re-weigh the charge with the pan...this is now my charge weight for the rest of my loads. Also, if the scale's native unit is grams, I'll change to measuring in grams instead of grains so it doesn't have to convert.

The scale will be more consistent without the need to keep up with the negative weight of the pan.

Where do you get multiple pans to use on a little scale?

 

[RegionRat]

Where do you get multiple pans to use on a little scale?

Takes a little digging.

Sometimes the company that sells the scales offers them, but sometimes you find them from third parties.

Try a little internet search and see what pops up. Worse comes to worse, you can try a search on Midway for accessories and should see a few options.


search was for "scale pans" on Amazon.

https://www.amazon.com/Powder-Lengt...-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1


https://www.midwayusa.com/s?searchTerm=scale+pan

 

[6Creed73]

Where do you get multiple pans to use on a little scale?

It's just a typical powder pan, any pan will work. I don't use a little scale though, I actually use a pretty large analytical electromagnetic force balance. It doesn't really have a drift problem, but I still measure my charges with the pan weight...it just makes sense that a scale will be more consistent by removing unnecessary variables.

 

[chromatica]

I try to let my scale warm up for 30 minutes before using it. I will re-zero the scale with the pan on the platter before I start measuring charges. I always use my RCBS beam scale as the final arbiter of accuracy. This comparison shows me that my scale occasionally drifts and does not always produce repeatable results. At the beginning of the session, I might have to trickle up to 44.34 to get a charge that balances on the beam scale set to 44.3. Later in the session I might only need to trickle up to 44.30 or 44.28 as seen on the digital display. This is true even when the empty pan displays a 0.0 reading. I have found that trickling up to my target charge weight will give me a different result than if I throw the exact right charge without trickling.

I replace the pan and check the display before I dispense each charge from my powder measure. Every once in a while, the scale will display a .24 or .30 grain offset (instead of 0.0) for the empty pan. Then I will hit the TARE button to re-zero the reading. It can be tedious to finish a tray of 50 rounds, but I am getting to know the ins and outs of my scale. I hear that owners of even the most expensive scales still struggle with drift and repeatability - sometimes chasing down electrical interference emanating from lighting fixtures. I don’t want to go down that rabbit hole.

 

[6Creed73]

I try to let my scale warm up for 30 minutes before using it. I will re-zero the scale with the pan on the platter before I start measuring charges. I always use my RCBS beam scale as the final arbiter of accuracy. This comparison shows me that my scale occasionally drifts and does not always produce repeatable results. At the beginning of the session, I might have to trickle up to 44.34 to get a charge that balances on the beam scale set to 44.3. Later in the session I might only need to trickle up to 44.30 or 44.28 as seen on the digital display. This is true even when the empty pan displays a 0.0 reading. I have found that trickling up to my target charge weight will give me a different result than if I throw the exact right charge without trickling.

I replace the pan and check the display before I dispense each charge from my powder measure. Every once in a while, the scale will display a .24 or .30 grain offset (instead of 0.0) for the empty pan. Then I will hit the TARE button to re-zero the reading. It can be tedious to finish a tray of 50 rounds, but I am getting to know the ins and outs of my scale. I hear that owners of even the most expensive scales still struggle with drift and repeatability - sometimes chasing down electrical interference emanating from lighting fixtures. I don’t want to go down that rabbit hole.

What you are describing is exactly why I do it the way I do. Scales only really drift when you zero a pan and it has to deal with negative weight. You can speed things up quite a bit by not zeroing the pan...just weigh your charge with the pan.

Since you check against the beam scale anyway, you simply get your initial charge weight on the beam scale. Then zero the empty scale and weigh the powder charge with the pan. This is your weight for the rest of the charges. No more drift because the scale isn't zeroed to the pan.

 

[Rocketvapor]

Scale instability or DRIFT can be caused by a few reasons.
One may be the stability of the internal electronics.
An internal voltage reference or the A to D converter may have short term noise or longer term drift.
With a precision voltmeter, specifications are usually stated for a cal period that can be a year.
Your scale, load cell or Force Balance, has a "voltmeter" inside.

Cheaper load cell scales may have an independent voltage source for the load cell and another for AtoD reference. Better scales will use a single stable reference for both. Load cell excitation and AtoD reference will thus be a fixed ratio, tracking electronic noise or environmental changes more closely. Reference voltage goes up a few ppm, excitation voltage goes up the same amount.

Your environment may cause drift due to temperature drift.
Air temperature is only part of the issue. If air temperature is different than the mass of the scale or bench/platform then heat will move to and from the scale. A bench that is 75F and an air temperature of 72F will likely cause drift as the bench tries to heat the scale and the air tries to cool it. A cold or hot nearby outside wall or floor will cause instability. Air drafts are seldom the same temperature as your scale's internal components. Body heat usually doesn't cause issues until you go beyond the milligram sensitivity level. The recent trend is to use a surface plate under your scale. Not a bad idea as it adds a massive amount of mass to the scale dampening vibration but it also works like a heatsink adding temperature stability to the scale.

Electrical power noise and fluctuation seems to be an issue with digital scales, even with the favorite FX120.
Figure out what devices are on the same breaker circuit as your scale. When I set up in the kitchen the microwave causes a lot of electrical noise in the power. I have to stop when I heat up my coffee
My current loading corner is close to my modem mounted on the wall plugged into the same power strip as my scales. Less than 5 feet from the scales.
Shutting the modem off, on, low or heavy usage on wifi, cell phone doesn't affect my scales (EJ-54D2, cheaper digital scales, or ER-182A). Power dips when the HVAC compressor starts but levels out after a few seconds.
Same with the electric hot water heater. Once every couple of hours, power dips for a few seconds.
An AC voltmeter on your scale circuit might be helpful in troubleshooting. Some power conditioners might actually make things worse. Voltage issues can have various frequencies. Ferrite core chokes can help with noise from a few kilohertz to many megahertz. A digital wall wart keeps line voltage out of the scale's power supply and most have some level of regulation. Internal regulation and filtering are common with precision lab voltmeters normally operated in close proximity to other instruments. Why is it a problem with a digital scale?

Static is a BIG problem when working with static sensitive plastics or gun powder. Static electricity pulls or pushes pretty much like a magnet. Fill your trickler with powder and it could take hours for the static to dissipate. Same for dumping a charge into a pan. You could also be charging things you handle. While it could look like DRIFT, it's actually external to the measuring circuit. Is your plastic draft shield causing reading drift?

Menu options should be explored for stability bandwidth and zero capture. Cheaper scales don't usually have options to change measuring parameters. The "Autozero" function is often misunderstood. IF you have options, try autozero OFF. Test your scale at a low but nonzero reading for stability and repeatability. A good check weight of a few grams, or even something that is fixed and stable can be used to evaluate drift. Most will spend hours developing and testing a load, but expect a precision reloading bench to be plug-n-play. Know what level of precision you can expect with a digital scale. Calibration @ full scale is almost useless. A 100 gram scale used to measure powder charges in the 2 to 3 gram range needs to be checked near the actual load most used. Test for zero stability (without autozero), or near zero if you can't turn it off, and check for linearity errors at weights you might use.

Even if you don't think you need extra digits beyond a milligram level, test your weighing process to BETTER than neded.

 

[JFrank]

After several years of beam scales I just started using the fx120 and I see no drift from cell phones or electrical out lets or lighting, whereas my other electrics drift beyond the limits of my program despite all the ideas guys come up with.
If you want to check your work, use vials to store loads then re weigh them a couple days later. You may be surprised to see your program isn’t where you thought it was.
Jim

 

[Rocketvapor]

I have used a few different scales, some I liked, some I didn't.

I have a cheap 300 gram milligram scale (300,000 counts) with AC or rechargeable internal battery that is accurate to a count or two, but not useful for trickling.
The load cell (500gram, German made) is a sturdy beast on a steel base.

Also have the same scale in a 3kg range, 0.01g resolution.

Checking two scales at the same time. Set little scale on pan, tare, weigh.

Scales with smaller full scale values, like 20 grams full scale often have a very flimsy load cell mounting half bridge, and are susceptible to abuse.

One old cheapo that I use for case sorting has a 500 gram range with 0.01 gram resolution.
Good to a few counts, but fast.

 

[rdb8847]

After several years of beam scales I just started using the fx120 and I see no drift from cell phones or electrical out lets or lighting, whereas my other electrics drift beyond the limits of my program despite all the little tricks guys come up with.
If you really want to check your work, use vials to store loads then re weigh them a couple days later. You may be surprised to see your program isn’t where you thought it was.
Jim

Hello Jim, Where do you purchase the vials? Roger from Rollins

 

[JFrank]

Hello Jim, Where do you purchase the vials? Roger from Rollins

These are (cone top) one dram vials purchased from Amazon, I use a 20 g shotgun cartridge box to store or carry a smallish quantity.

@newbieshooter enlightened me to these vials.

 

[6Creed73]

Scale instability or DRIFT can be caused by a few reasons.
One may be the stability of the internal electronics.
An internal voltage reference or the A to D converter may have short term noise or longer term drift.
With a precision voltmeter, specifications are usually stated for a cal period that can be a year.
Your scale, load cell or Force Balance, has a "voltmeter" inside.

Cheaper load cell scales may have an independent voltage source for the load cell and another for AtoD reference. Better scales will use a single stable reference for both. Load cell excitation and AtoD reference will thus be a fixed ratio, tracking electronic noise or environmental changes more closely. Reference voltage goes up a few ppm, excitation voltage goes up the same amount.

Your environment may cause drift due to temperature drift.
Air temperature is only part of the issue. If air temperature is different than the mass of the scale or bench/platform then heat will move to and from the scale. A bench that is 75F and an air temperature of 72F will likely cause drift as the bench tries to heat the scale and the air tries to cool it. A cold or hot nearby outside wall or floor will cause instability. Air drafts are seldom the same temperature as your scale's internal components. Body heat usually doesn't cause issues until you go beyond the milligram sensitivity level. The recent trend is to use a surface plate under your scale. Not a bad idea as it adds a massive amount of mass to the scale dampening vibration but it also works like a heatsink adding temperature stability to the scale.

Electrical power noise and fluctuation seems to be an issue with digital scales, even with the favorite FX120.
Figure out what devices are on the same breaker circuit as your scale. When I set up in the kitchen the microwave causes a lot of electrical noise in the power. I have to stop when I heat up my coffee
My current loading corner is close to my modem mounted on the wall plugged into the same power strip as my scales. Less than 5 feet from the scales.
Shutting the modem off, on, low or heavy usage on wifi, cell phone doesn't affect my scales (EJ-54D2, cheaper digital scales, or ER-182A). Power dips when the HVAC compressor starts but levels out after a few seconds.
Same with the electric hot water heater. Once every couple of hours, power dips for a few seconds.
An AC voltmeter on your scale circuit might be helpful in troubleshooting. Some power conditioners might actually make things worse. Voltage issues can have various frequencies. Ferrite core chokes can help with noise from a few kilohertz to many megahertz. A digital wall wart keeps line voltage out of the scale's power supply and most have some level of regulation. Internal regulation and filtering are common with precision lab voltmeters normally operated in close proximity to other instruments. Why is it a problem with a digital scale?

Static is a BIG problem when working with static sensitive plastics or gun powder. Static electricity pulls or pushes pretty much like a magnet. Fill your trickler with powder and it could take hours for the static to dissipate. Same for dumping a charge into a pan. You could also be charging things you handle. While it could look like DRIFT, it's actually external to the measuring circuit. Is your plastic draft shield causing reading drift?

Menu options should be explored for stability bandwidth and zero capture. Cheaper scales don't usually have options to change measuring parameters. The "Autozero" function is often misunderstood. IF you have options, try autozero OFF. Test your scale at a low but nonzero reading for stability and repeatability. A good check weight of a few grams, or even something that is fixed and stable can be used to evaluate drift. Most will spend hours developing and testing a load, but expect a precision reloading bench to be plug-n-play. Know what level of precision you can expect with a digital scale. Calibration @ full scale is almost useless. A 100 gram scale used to measure powder charges in the 2 to 3 gram range needs to be checked near the actual load most used. Test for zero stability (without autozero), or near zero if you can't turn it off, and check for linearity errors at weights you might use.

Even if you don't think you need extra digits beyond a milligram level, test your weighing process to BETTER than neded.

A lot of good points here. I plug my digital scale into a line conditioner and I consider that imperative for a consistent digital scale, they need clean, stable power.

Your point about static is also a good one. I wipe my pans with a used dryer sheet, and only use scales with glass draft shields. These highly sensitive scales can be finicky, but if you take the steps to ensure they are setup to perform optimally...they are very precise and convenient.

 

[BoydAllen]

This costs about $25 on Amazon, and you can easily trickle. If you use the method that I mentioned at the start of this thread, it works very well.

 

[CharlieNC]

This costs about $25 on Amazon, and you can easily trickle. If you use the method that I mentioned at the start of this thread, it works very well.

Based on your suggestion I purchased that scale, and use it to confirm every charge from the Charge Master which generally adds around five seconds each. Over a couple of years both have shown excellent agreement, and that little digital has performed well.

 

[Doom]

Prior to weighing every charge the scale should be zeroed. That is common lab practice. In lieu of that you weigh the pan prior to every measurement and subtract the pan weight from the weight of the pan and powder. Zero/taring a scale/balance dosn't affect the differential weight measurement.

The following is extracted from the FX-120i manual:

• Press the RE-ZERO key before each weighing to eliminate possible errors.

Many scales have an auto zeroing capability.

 

[Dgd6mm]

This costs about $25 on Amazon, and you can easily trickle. If you use the method that I mentioned at the start of this thread, it works very well.

I purchased this scale shortly after you suggested it Boyd. I'm glad I did, thanks for the tips.

 

[6Creed73]

I purchased this scale shortly after you suggested it Boyd. I'm glad I did, thanks for the tips.

I've been thinking about getting a small, cheap scale for loading rounds at the range. Which scale is it?

Edit: Nevermind, I just noticed it's the Gem20

 

[Doom]

Based on your suggestion I purchased that scale, and use it to confirm every charge from the Charge Master which generally adds around five seconds each. Over a couple of years both have shown excellent agreement, and that little digital has performed well.

I also purchased one this past weekend and I am impressed. I run tests when using a new scale to see how it responds and also what kind of repeatability I get. You can run this with calibration weight or in this case I ran it with a 60 grain NBT that I use to spot-check my Chargemaster. The Chargemaster spots it at 60.2 grains. I ran two tests with 20 separate measurements each. One was zeroing/taring before each weighing and one without. The calibration was verified during the initial weighing, mid-test and end test. Here are the results:

Zeroing:


Non zeroing:


Statistically the means are different and the standard deviations are considered equal. Can't say with certainty that zeroing every time is important or note but this test was run in my air conditioned house. If the temperature was more variable I think the results might have been different.

I did notice that the position of the wind shield affected the calibration. Need to make sure the shield is where it will be when weighing when the calibration is done. All in all it seems like a pretty good scale to have around.