Does anybody have experience with the RCBS digital scale and if so, can you tell me how you liked it?

I don't know which one I have, but it's the one that goes with the electronic powder dispenser. It's actually my old shooting partner's, he brought it down last year as we mostly load together anyway, but it's an excellent scale and gives very accurate loads, some of most consistent deviation my chrono has ever recorded.

Here's the one I'm using. It doesn't say the number on it, but it's the one that talks to the dispenser.

http://i136.photobucket.com/albums/q172/faucettb/Reloading/RCBSScale.jpg

The RCBS 750 has limited range (750 grains max) compared to the older model that faucetb has which max's out at 1500 grains. His was the first model made that was reasonable in price and was made by PACT who still markets an improved version. RCBS began marketing the 750 as a lower priced alternative to the first model with update features--i.e. built in battery vs external power only. I have both models and they work very well with the first model being USA made while the 750 is made in China. I believe the 750 is not quite as accurate as the original but that could be illussion on my part. The original is at my reloading bench and the other travels whenever needed. At times I've felt the 750 was hard on batteries but that could be old batteries not fresh ones causing the problem.

Thanks. The reason I asked is that I bought one a week ago and found that it measured off by nearly one grain after calibrating and zeroing to the powder pan. I was planning on replacing it, and RCBS has offered to do so at no charge, however I thought I might upgrade to the 1500 if other people have had bad experiences.

I've no experience with the 750, but I got a PACT DPPS, same as the RCBS 1500, for Christmas of 1995. It's rock solid most of the time, and I've figured out most of it's glitches. I think the newer ones are more stable, but mine likes a half-hour warm-up for production work. It will go nuts if I let the sun shine on it, which does happen in mid-afternoon if it's in it's usual spot on the bench. A move to the other side fixes that.

Mine came with a plastic powder pan, which has a bad case of static cling. There's various half cures for that, but the permanent cure is a metal pan.

Bye
Jack

I have the 1500 grain model and the powder dispenser.
I had some ups and downs with the unit when I first bought it but Beartooth Forum member Greg Mushial gave me some tips on its use.
First off it requires a good warm up. I warm my scale 30 minutes prior to using it. I find when using the powder dispenser this ensures repeatability of the dropped charge.
The unit is sensitive to cold weather; this is actually an understatement as I have found the unit required a good hour of warm up for accurate reading in my work room when the temperature was below forty degrees.
Greg has his set up on his bench and has it running all the time. His unit seems to work quite well with his trickler. I have never fully developed my technique with the trickler and digital scales. I use the adjustable Lyman trickler and while it works well I lift the pan and set it back down to confirm my reading before I pour a charge. When the dispenser is operating it is very accurate – provided I have used an adequate warm up period.
My father uses a Lyman electronic scale and it seems to work a little better with the manual trickler.
The advantage of the RCBS scale and dispenser (made by Pact) is its accuracy and speed with hard to meter powders such as 800X. The large flake powders meter very accurately and quickly from the dispencer.
I use the Lyman funnel pan after calibrating the scale.

So can you use the scale at low temperatures as long as it is turned on for an extended period of time?

I just went back to Sportsman's Warehouse and exchanged the 750 for a 1500. The directions warn about storing the scale in frozen temperatures and that it should be used at room temperature. My reloading bench is in a garage that I don't regularly heat. The temperature seldom drops below freezing but it is often 40 degrees in there. I have an electric heater that I use when I work on reloads but I don't run it all the time.

Your room sounds like mine. It often drops down into the teens at night in the room. I generally go in and start a fire in the iron stove or turn on an electric heater but not always. I plug in the scale and an hour later it is ready to go. I have used the scale at 40 degrees and probably in the high 30’s without a problem but I gave it a good warm up. Once warm it works fine.
I have never tested Dads Lyman scale in the cold so I don’t know how well it operates.

Does the 1500 have any features better than the 750, other than the increased capacity? I can't think of a reason why I would ever need to weigh more than 750 grains. Maybe just not thinking ahead.

Does anybody have experience with the RCBS digital scale and if so, can you tell me how you liked it?

I had one several years ago, and it only lasted about four months. If you buy one MAKE SURE that you also have a "Surge Protector" as a power surge, is what "fried" my scale. I went back to the balance beam type scale, but if I ever buy another digital, I will buy one that runs on batteries. ;)

The scale topic comes up periodically. They mostly all have plastic load cells now, to keep costs down. The original Dillon Terminator did not, I know, but that has changed. The only metal load cell scale I am familiar with that is available now is the Aculab VIC123 sold by Sinclair. About $300, but it does resolve 0.02 grains, which is a bonus. This scale's load cell is powered whenever it is plugged into the wall. Only the rest of it shuts down. That way it stays ready to use.

I also own a number of plastic load cell scales, including the PACT. The all exhibit some degree of hysteresis, so if you leave a weight on it for awhile, the plastic stress relieves and it tends not to go all the way back to zero. Most have circuits that re-zero them when they get close to zero, which covers this up, but doesn't stop the load cell calibration from drifting toward an offset. PACT makes the extra effort of using two calibration weights to try to correct non-linearity introduced by the hysteresis of the plastic, but I discovered, when I got the Aculab, that my lower calibration weight was off a bit, which explained some of the problems I had with keeping it accurate.

That scale also drifts with temperature, as others mentioned. None of the plastic load cells have great temperature compensation. They try, but steel and, especially, aluminum load cells are easy to temperature compensate because the metal spreads the same temperature rapidly to all the strain gages in the cell. Plastic does not, so you can get temporary temperature gradients across plastic cell beams that defy all attempts at drift compensation until they have had time to equalize.

Additionally, none of the electronic scales made for reloading, including the Aculab, have Faraday shields, so they can be very sensitive to fluorescent lighting or to sharing a power line with a fluorescent fixture or even a computer. You want not only a surge suppressor to run these scales off AC line power, but also a noise filter as well. Building a Faraday cage to use the scale in can help in some environments, but is a bother. Combining it with a draft shield box makes some sense, though. With a completely surrounding draft shield, putting the scale on a slab of something (I use a cheap B grade granite surface plate) will help keep the temperature even. I recommend you go to Radio Shack and pick up a static bleed-off wrist strap to use with these scales in dry weather. You can sometimes see the proximity of your body to the scale shift its reading due to static charge in those condiditons.

I should probably propose a tech note on how to make a filter and Faraday cage.

Below zero temperatures can make some plastics, especially polypropylene, drop below their glass transition point and become quite brittle. You don't want to put a load on a plastic load cell at low temperatures for that reason. Even if the plastic has plasticizers to keep if from growing brittle, the hysteresis gets very bad at low temperatures and hard to recover from. It is also possible for the adhesives holding the strain gages to the load cell beams will embrittle or lose hold at low temperatures, which would destroy the load cell.

Unclenick, that was informative summarizing all the bits and pieces of information I've seen posted over the years on this subject. Guess my only question is what good is scale accuracy greater than +/- .1 grain. Most of us are not bench rest shooters in persuit of that holy grail "one hole shot group". Does that help in repeatability having a small accuracy range?

“I recommend you go to Radio Shack and pick up a static bleed-off wrist strap to use with these scales in dry weather.”

This is easy to demonstrate when the humidity is below 3% you can put on quite a show by passing your handover and around the scale body. I try to not lean over the scale when weighing or dispensing charges. I use a card board box windshield when I run the ceiling fan in summer.
Quite a few shooters reload at our shooting range and while a few use battery operated scales most use high quality powder measures and have their charge settings recorded in a notebook. The high quality powder measures cost more than my RCBS scale and powder dispenser, work very well in the wind and still have a few problems with extruded powders.

. . . Guess my only question is what good is scale accuracy greater than +/- .1 grain. . .

The reason for buying that particular scale is to get the metal load cell, IMHO. The fact it resolves 0.02 grains is, as I said, merely a bonus. As to what value that bonus might have, keep in mind that resolution is just how small a difference in weight is displayed, while accuracy is how close to true that number actually is? Not the same thing, as when Seatleroadwr said his scale was off a grain after calibrating; it's resolution would still have been 0.1 grains displayed, despite the error.

It is one of the curses of the digital age that people tend to believe information displayed as numbers without question. A conventional beam balance scale lets you see the arm settle and whether it settles in the same spot after tapping it up in one test and down the next? If there is hysteresis, there is a difference in the two and you can eyeball an average in between. In the case of the Aculab, I like being able to see one decimal place further out than I actually am interested in measuring. It's like being able to see the beam settle on a balance. It gives me some indication of how much drift there is in the numbers and whether a draft or static charge is getting near to changing them? It's also a good indicator of when to re-zero and re-weigh a sample?

That scale itself, incidentally, measures internally in ten-thousandths of a gram (0.0015 grains, approximately) and averages 10 readings then rounds up to display a result. That's the other reason I have the granite surface plate. It's a great vibration damper.