Fx-120i zero drift

[PracticalTactical]

IT DOES NOT ADD UP

Oh my math adds up just fine with REALITY.

The .02 with .03 tolerance you claim is a flat out lie. You are confusing readability with the actual weight value.

An almost universal accuracy standard for scales is the variance is plus or minus twice the value of readability.

The FX120 displays 0.02 grains... so real world accuracy under ideal conditions is plus or minus 2x0.02 = 0.04 grains plus or minus equals 0.08 grains total variation.

I challenge you to actually test it against an analytical balance.

 

[SGK]

I think that's probably a very good idea. I would dearly love to run the scale/autotrickler system from a battery, but my complete lack of electrical knowledge is stopping me from rigging this up.

I can't imagine any reason to run it from a battery. My scale drifts a little while warming. This is to be expected. After that it is dead steady. I don't leave mine on and I transport it from a cupboard to tabletop for use.

Also, if you are using the Autotrickler, the scale is re-zeroed every single time you put your scoop on it. The only drift that your measuring encounters then is any during the very short time it takes to pour the charge.

 

[SGK]

The FX120 displays 0.02 grains... so real world accuracy under ideal conditions is plus or minus 2x0.02 = 0.04 grains plus or minus equals 0.08 grains total variation.

More like 1 STD DEV of repeatability is 0.001 grammes or 0.0154 gn (from published specs). 4 standard deviations (95% of readings) is a range of 0.06 gn or approx 3 kernels. +/-1.5 kernels. 68% within 0.03 gn range or 1.5 kernels. That's plenty good enough. To put it in perspective a 41 gn load would have approximately 2050 kernels of powder. And you're worried about the difference from 1, 2 or 3 kernels on target.

 

[6bra1k]

Oh my math adds up just fine with REALITY.

The .02 with .03 tolerance you claim is a flat out lie. You are confusing readability with the actual weight value.

An almost universal accuracy standard for scales is the variance is plus or minus twice the value of readability.

The FX120 displays 0.02 grains... so real world accuracy under ideal conditions is plus or minus 2x0.02 = 0.04 grains plus or minus equals 0.08 grains total variation.

I challenge you to actually test it against an analytical balance.

how about the other way around.
you CLAIM IT AINT ACCURATE.
YOU PROVE IT.......FACTS AND DATA NOT "almost universal accuracy standard for scales"..THAT AINT A FACT, IT IS AN OPINION

 

[brxbrad]

replace the inverter....

 

[Rocketvapor]

A few observations of this conversation;
This has been going on for several years with the 120i.
Static with the plastic shields in place,
Electrical power,
Unstable temperature.
Stability and zero settings in the menu.

The typical using range of this 120 gram scale is 2 to 5 grams of powder with a trickle to final value.
The scale responds to weight between zero and full scale, normally used closer to zero than full scale.
Drift is likely a problem with external input or zero tracking.

Test against check weights near the target weight or use the A, B, C nickle test .
Try to determine if all readings are subject to drift (greater than +/- one count) or just those that rely on the scale's auto zero/zero tracking feature. This feature will let the scale read 0.00 for days on end.
Proves nothing.
If so, try the FAKE ZERO technique (from a previous thread).

My EJ-54D2 goes crazy when the microwave is running (same circuit in the kitchen) but not with the toaster or coffee maker (except when brewing).
Drift due to drafts on high range, 52g/milligram resolution, when the HVAC isn't running is small and cause no problems with the shields removed . While the fan is running I get a couple counts of drift and have to take a break.
I monitor the temperature under the scale.
On low range (0.0002g resolution) the draft shield is needed

 

[michaeljp65]

As i was a lab tech for nearly 20 years i learnt to tare the balance every time i placed something on the pan.

 

[SGK]

As i was a lab tech for nearly 20 years i learnt to tare the balance every time i placed something on the pan.

Yeah. The autotrickler does this automatically if the drift is within 0.02 grain (if I recall the amount properly) else you have to do it manually.

EDIT: corrected amount

 

[Rocketvapor]

Have you ever seen 2 grains of DRIFT?

 

[SGK]

Doof. I forgot the .0. Here's a clip of a discussion with Adam some time ago:

+/- 0.02. In which case, the scale will automatically correct itself to zero in about 1 second. This is how the scale works. The trickler waits 1 second for this to happen, and then starts. At most, the scale can only be off zero by 1 kernel.
+/- 0.04 or greater. In which case, the scale will NOT automatically correct itself for drift, and the trickler will not start. Either there has been some drift, or there are a couple kernels in the pan. Check, rezero, and continue.

 

[ronemus]

You also need to be careful in handling anything you weigh - skin oils, sweat, etc. will add up. Handle calibration and check weights with tweezers. If it's hot, wear gloves (light cotton gloves will do if they're kept clean. Wash your hands and get them dry before you start a session.

Minimize drafts. I only have one side of the draft shield removed and have a cardboard box around all sides except the front. Keep your hands away from the scale when weighing, and definitely don't walk around.

Filter the power (it doesn't like line noise) - I use a Tripp Lite ISOBAR6Ultra Isobar 6 Outlet Surge Protector.

Work with a stable floor (I work on the basement slab) and use a sturdy table. I make a crude vibration isolator by putting a granite surface plate on soft foam rubber.

 

[6BRA]

Does the Isobar2 2outlet have the same filtering/conditioning effect?Tripp Lite IBAR2-6D Isobar 2 Outlet Surge Protector Power Strip, 6ft Cord, Right-Angle Plug, Metal, Lifetime Limited Warranty & Dollar 25,000 Insurance https://www.amazon.com/dp/B0000510Z9/ref=cm_sw_r_apan_i_QRXJ4JK5Z99Z5H5YXBT6?_encoding=UTF8&psc=1

 

[One Eye Pete]

My fx120i has been rock solid for the eight years I have owned it. I have a certified set of test weights that I use and it has always read correctly within .02gn. I cal it with a 50g test weight and then check it with a 3g test weight. It has almost always been spot on with very little drift.

The only time I had problems with this scale was when the power supply started to go bad. I used it with a gen 3 autotrickler and the original power supply that came with the scale. The autotrickler instructions said that certain model number power supplies were OK to use with the added load of the autotrickler. My power supply was of the correct model number so I continued to use it. I kept the additional heavy duty power supply that came with the autotrickler as a spare. When the problem started the scale would get "flaky" and drift like crazy then it would display a code of Lb and lock up. I checked my manual but couldn't find what the Lb code meant. I then read that as an option the FX120i can come battery powered. That's when the little light bulb in my head lit up and it dawned on me that Lb meant "low battery" I switched to the heavy duty power supply supplied with the autotrickler and the problem was resolved.
To me the FX120i is absolutely the best reloading scale available for the money. Of course you can buy a more accurate laboratory balance for a lot more money but the FX120i measures down to a single kernel of most powders. My guess is that most shooters will never see the difference from a more accurate laboratory balance show up on the target. There are a lot more factors that will put you in the 9 ring before plus or minus one kernel of powder.

 

[Turbulent Turtle]

I've been running a Fx-120i for quite a while, and I've noticed that my zero drifts a fair amount over the period of a loading session. If I put my powder pan on the scale, and zero it, the tare weight will drift quite a bit between charges. My shop is a stand alone 15'x20' building, with no fans or air exchangers. Where do I start to rectify this?

Any fluorescent lights in your shop?

 

[ronemus]

Does the Isobar2 2outlet have the same filtering/conditioning effect?Tripp Lite IBAR2-6D Isobar 2 Outlet Surge Protector Power Strip, 6ft Cord, Right-Angle Plug, Metal, Lifetime Limited Warranty & Dollar 25,000 Insurance https://www.amazon.com/dp/B0000510Z9/ref=cm_sw_r_apan_i_QRXJ4JK5Z99Z5H5YXBT6?_encoding=UTF8&psc=1

The 6-outlet strip has 3 banks of 2 outlets, and the isolation gets higher as you go; the 2-outlet strip won't be a good as the 3rd bank.

 

[6BRA]

Even if you are only running 1 device off of it?

 

[Doom]

Most probably you have temperature drift, either due to not having enough warm up time or variable ambient temperature. The solution is in the manual and is common practice in laboratories:

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

 

[piie]

I think that's probably a very good idea. I would dearly love to run the scale/autotrickler system from a battery, but my complete lack of electrical knowledge is stopping me from rigging this up.

Buy a small UPS with pure sine wave output - it filters the power supply and also protects against surges and lightning (to a small extent), and you'll have the power backup to boot.

Also, invest in a proper foundation for your scale - you don't have to buy the extremely expensive granite blocks for analytical balances - I use a piece of off-cut granite counter top - but a very thick one - it's the mass you're after primarily, and the flatness - make sure you have the scale setup perfectly level. I also replaced my fluorescent lighting with LED lighting - but must admit, I never saw it effect my scale in the past - but the LED's are brighter nonetheless, so not sorry I did that. Another poster also pointed out - look for a stray kernel - clean the scale properly every once in a while by lifting up the covers as well as the weigh "base", and try to make a mental note of where you are positioned if/when you notice drift - eliminate your own breathing into the weighing area...

I'm busy saving up for a proper F class calibration weight, unless you have an FZ, it may also be something to consider.

 

[Papa Charlie]

Several things affect analytical scales and drift

1) breezes, even your breath
2) vibration, it does not take much vibration to affect your zero and no, it does not come back to zero. I use a small 3"x12"x18" granite plate under my scale to control small amounts of vibration. This of course depends on your flooring and if you use an isolated bench for the scale separate from the rest of the operations.
3) Fluorescent lights, fluorescent lights emit energy which can have an affect on the scales. Use LED or incandescent instead.
4) Cell phones, cell phones also emit energy that can have an affect on your scale. I keep mine in another room while measuring power
5) I warm up my scale for at least 6 hours before attempting to use it. These analytical scales require a very stable environment.
6) Bumping the scales balance pan while using them. If you are not careful and bump the scales balance pan while putting the pan back, this can cause the scale to drift as well.
7) Static, these scales are very sensitive to static. For that I run an anti static mat under my scale that is connected to a sensor that tells me if the mat builds up any measurable static. Over kill but picked it up from a auction at a lab and has definitely had a significant affect on my scale.
8) The cleanliness of the power feeding the scale has a huge affect on the scale. I run a pure sine wave UPS that ensures that my voltage and frequencies are constant. You would be surprised at the voltage fluctuations that an average home has. I have tested may, past work, that showed to be constantly floating into a Brown out, which is any power that falls below 90v. The UPS will switch to battery if the voltage drops below 103v.

There are other ways to protect your scale and most are very simple. Given the amount of money we spend for scales and our other equipment, it does not make sense to not allow an expensive analytical scale to do what we purchased it to do. I would not consider these to be plug and play tools.

I don't use a FX120i, I have a Sartorius that I also picked up at a lab auction that had just been calibrated. It is capable of reading down far below a single kernel of powder but of course I only have it set to read to 1/100 of a grain, like most FX120's.

Given my environment, I check the tariff several times during my process. But I have a rather unique situation than most.

 

[SGK]

Also, invest in a proper foundation for your scale - you don't have to buy the extremely expensive granite blocks for analytical balances - I use a piece of off-cut granite counter top - but a very thick one - it's the mass you're after primarily, and the flatness - make sure you have the scale setup perfectly level.

The scale is light. Having it on something heavy that's not sitting on EVERYTHING rock solid or isolated from everything below isn't going to help much at all. Personally I use mine on a solid table. If you head down the granite (or similar) block you should add sorbothane pads underneath the slab.

https://www.amazon.com/Sorbothane-Hemisphere-Non-skid-Adhesive-Durometer/dp/B0042U6ZDU/ref=sr_1_1_sspa?crid=1UB4RCXOOOSJP&keywords=sorbothane+feet&qid=1648557547&sprefix=sorbothane+%2Caps%2C106&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyU0ZUUzRGRE9MVzkyJmVuY3J5cHRlZElkPUEwMDAzNjM2MkFEV0pZWThBOVFUUCZlbmNyeXB0ZWRBZElkPUEwNTU0MDc5MUlGWTVNTE0xUlVORSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Then you have insulated mass on which to sit your scale. But it doesn't sound like this is the source of the OP's issue.