Line conditioner for scale drift??

[DRNewcomb]

... I collect the 'distilled' water it produces for washing brass....

Keep in mind that your "distilled" water includes anything that was floating around in the air when it was condensed. I assume you implied a next to "distilled".

 

[spclark]

I assume you implied a next to "distilled".

Pretty much, yes. For cleaning & rinsing brass it's good enough, better (less mineral content) & cheaper than what get's paid for drawn from city's water.

 

[seymour fish]

I work daily with precision analytical balances (I'm a research chemist) 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 van 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 antiststic 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 Pact scale/dispenser. 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.) on a slab of soft foam, but it may not be effective; really good vibration isolators are expensive.

Sorbothane sheet

 

[243Mendoza]

I gave up on scales based on strain gages and can't afford the mag lab scales. I now use a tuned balance beam.

 

[T-shooter]

I'm having some issues with drift on my scales and I just can't afford to buy a $1k scale. Anyone use a "line conditioner" for their scales? If so, which brand/model?

What about ferrite chokes/beads (http://www.oldwillknottscales.com/fair-rite-rct-2-ferrite-bead.html) -anyone use these with any success?

I used these chokes and noticed an improvement. Install then according to the directions at that site (double wrapped). I used 2 on my FX-300i scale. I had some cheap ones from Ebay that did nothing. I also used the Tripplite LC1200 line conditioner and since I had it, a Tripplite 2 outlet unit into it too which may have added a bit more line filtering. The combination of these 3 things made my scale rock solid.

 

[davecb]

I use a tripplite 1200 line conditioner and ferrite beads on the power cord going to the scale and my auto trickler. I don't know if it's necessary but I also have my scale and auto trickler sitting on an ESD pad that's grounded. I have no issues with drift. I am now using an Entris 64 scale but I also use to have a strain gauge scale and had no issues with this setup.

Dave

 

[RampedRaptor]

https://www.amazon.com/gp/product/B00009RA60/?tag=accuratescom-20

I never had a issue with my fx120i but I run one of these for cheap insurance

 

[normmatzen]

The first order problem with drift in a strain gauge balance is not the noise on the power bus, but the nature of the strain gauge itself.
the strain gauge is nothing but a tiny silicon resistor whose value changes with flexure of the resistor. The resistor is glued on to a beam of some sort that suspends the pan. With a weight on the pan, the beam bends putting strain on the resistor and this strain is measured and indicated in terms of grams, grains or what ever unit is desired. As these are typically inexpensive balances, often designed to make one quick measurement soon after the zero button is pressed, the inherent accuracy is more than good enough. The operating point of the strain gauge output includes effects of temp change and other environmental effects as well as simply not designed for the stability and accuracy we need for, say, bench rest. the beam will change dimensions microscopically with temp changes which adds a bias to the strain gauge. Things like vibration can also effect stability.

Can't make a silk purse out of a sow's ear!

 

[Webster]

I'm having some issues with drift on my scales and I just can't afford to buy a $1k scale. Anyone use a "line conditioner" for their scales? If so, which brand/model?

What about ferrite chokes/beads (http://www.oldwillknottscales.com/fair-rite-rct-2-ferrite-bead.html) -anyone use these with any success?

At work I had a lot of settling time on a very expensive scale. I tried weighing a sample holding the sample pan with various glove types. Vinyl, latex, nitril and carbon impregnated anti-static gloves. It turned out that the settling time was much shorter with the anti static gloves. I have a pair I don't need. Will mail to anyone if you reimburse for postage. Don't remember where we bought them from, probably VWR. Very expensive.

 

[Gina1]

I have a Bald Eagle powder scale... It drifts... But over time, 2 minutes or more. I've worked out a system to get around that. I've noticed right after the calibration procedure, it is dead on (I have some laboratory calibration weights) What works for me is I weigh out my powder load, say 32 grains, right after calibration, and check it several times (so I know it's right on). I then zero (Tare) the scale. I put the empty pan on the scale and add that 32 grains of powder to the pan. This gives me the pan weight + the powder (for this example 2,000 gains)
I then put the empty pan on my RCBS Charge master. After the powder drop I move the pan to the Bald Eagle scale, PRESSING TARE !!! just before I put the pan on the scale. I then add or remove powder to get to my charge weight. 32 grains, but reading 2,000 grains with the pan weight. I do this every time I throw a charge.
It is repeatable and accurate to +/- 2/100's of a grain. Also I run the scale only on batteries, which last several loading days.

 

[spclark]

Don't remember where we bought them from, probably VWR. Very expensive.

@ $17.50 a pair? No kidding!

 

[Webster]

@ $17.50 a pair? No kidding!

Free if I mail them.

 

[rardoin]

I use the TrippLite LC-1200 for a Sartorious E-64 on a pretty crappy circuit with a refrigerator and window AC unit and I have no drift. I don't have any chokes on the power cord to the LC 1200 or the balance.

 

[Delfuego]

A good UPS (uninterruptible power supply) works much better than a line conditioner. Line conditioners cannot really deal with power dips, only spikes.

 

[rardoin]

A good UPS (uninterruptible power supply) works much better than a line conditioner. Line conditioners cannot really deal with power dips, only spikes.

Not necessarily...

The average consumer UPS will do little remove RFI from the power line. It only comes "online" when the voltage drops to a certain threshold voltage for a certain time period. Otherwise the AC "passes" through the unit with thermistors in the circuit to limit inrush currents (offering surge protection). High end UPS devices, using a simplistic explanation, charge a battery and an inverter converts that DC to ac with sine wave conversion. This will greatly reduce/eliminate stray currents/RFI. The cheapest unit I could find was $550+. The LC units from Tripplite do have undervoltage and overvoltage correction...to a degree.

 

[Delfuego]

Cyberpower offers one with "AVR" for under $200 https://www.cyberpowersystems.com/product/ups/cp1500avrlcd/

I run a large APC "Smart" UPS designed for servers on mine. I can also bring a chargemaster to the range for load development too