digital scales help!!!

[joshb]

Will the use of beam scales increase your powder throw time compared to the digital scale and if so, any idea how much longer it takes to load with the beam scales?

After I get my thrower, scale and trickler set up, I can load a shell in about 30 seconds.

 

[Outwest]

I have had really good luck with my RCBS Chargemaster link scale.
I warm it up for 30 minutes and calibrate it every time I use it.

 

[ronemus]

I worked daily with precision analytical balances (I was a research chemist and instrument designer before retiring) 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 them 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 cardboard 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 and A&D fX-120i scale. 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.

Strain gage scales (all of them under $600) will drift - it's inherent in the technology, so frequent taring is necessary. Magnetic force restoration is used in electronic lab scales, but typically costs thousands to tens of thousands of dollars. The A&D FX-120i/FX-123 is the entry-level force restoration scale, and a real bargain at ~$600; drift is greatly reduced vs. strain gage scales (not entirely eliminated). If you can afford it I highly recommend buying an FX-123 or a used (now discontinued) F-120i.

 

[Tangent]

Agree with the above. I'd add use check weight each time around the weight range you intend to use. I spent a lot of time in labs and calibration was a big deal, records kept and audited. The caveat is that it's all relative to the accuracy that you require.

 

[64Rambler]

I worked daily with precision analytical balances (I was a research chemist and instrument designer before retiring) 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 them 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 cardboard 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 and A&D fX-120i scale. 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.

Strain gage scales (all of them under $600) will drift - it's inherent in the technology, so frequent taring is necessary. Magnetic force restoration is used in electronic lab scales, but typically costs thousands to tens of thousands of dollars. The A&D FX-120i/FX-123 is the entry-level force restoration scale, and a real bargain at ~$600; drift is greatly reduced vs. strain gage scales (not entirely eliminated). If you can afford it I highly recommend buying an FX-123 or a used (now discontinued) F-120i.

^^^^^^^ THIS!!

I'm still a research chemist and the A&D scales are truly a bargain for the performance they give - CE has the best prices I've seen. Most of the balances I work with are easily 10X the cost of the FX120i, but also are 4 and 5 decimal place readouts.
As said by several, make sure it's well warmed up, that the bubble in the level indicator is as centered as you can get it. If it has a grounding lug, use it. Static is probably the #1 enemy of balances - it even effects beam balances! I also run a separate ground wire from the next outlet to the front of the scale by the opening and make sure I touch it every time I pull the cup in and out - this drains the built up static on me and brings me to the same potential as the balance. Don't wear long sleeve shirts while reloading, the friction of the fabric rubbing on itself will generate static. Be careful about leaning on the bench while weighing. If you have a check weight, preferrably at the weight to calibrate the scale, use it! I calibrate every time I start weighing powder if the display is not 100.000g with the calibration weight. I was able to check my weight at work on 2 different 5 place balances and it came in at 100.00012g on both, so I'm pretty confident in the calibration on a 3 place balance.
If you can't get the balance to maintain zero with the pan on and off and back on, there's something wrong in the system somewhere, you just need to find the gremlin that's effecting yours.