Armory Sponsor
Posted: 8/17/2008 9:18:15 PM EDT
|
After reloading some 223 rounds my brother and I decided to sort the assembled cartridges by weight (approx 184gr) We started off with a Lyman DPS 1200 and when I rechecked some of the cartridges the readings were different by up to .4 grains than what the cartridge checked a few minutes earlier.hinking We tried it zeroing on a cartridge then sorting by weight difference and by zeroing the scale and separating by actual weight. We compared between scales and found they often differed by .2 and once in a while .3 grainshersIs there a solution or do we have to go back to the 10-10? |
|
Do you have air conditioning in your house? I've found that when it comes on, it changes the zero on my scale. I think, eventhough there is no direct draft, it increases the air pressure some, which will affect the zero on almost any precise scale. Also, if the barametric pressure is changing, that will affect your zero. Some days my scale stays dead on, other days it seems to wander. If I'm weighing on those days, I check the zero frequently with a standard weight. edit for spelling |
|
Are you talking about weighing the entire cartridge, or just the powder charge? i've found that with my Dillon powder charger, a number of things will change the weight of the powder charge; the most significant thing is the amount I let the handle "bang" when I return it to the upright position. Even with identical components, weight can change significantly. Bullets and brass can be off by .2 or .3 grains, easily. And this is with same-brand components: bullets out of the same box, brass w/ same headstamp. |
| you need to do the sorting before you load the cartridges. there is no way to derive any uniformity now becasue of all the variables being stacked. you have bullet weight variation, case weight variation. powder charge variation and even primer weight to consider. |
|
These are the reasons I gave up on electronic powder measures after trying about everyone that is made. Every @#@$% thing screws with the darned things. I use a old Redding balance beam scale from the 50's. Balance beams scales are not affected by moon rotation, electronic signals, or humidity. The electronic ones are affected. Purchased a Harrell Premium and never looked back. As long as I don't bump the upstroke, I'm +/- 0.1 grains everytime. If I bump the upstroke I throw it back in. |
|
No, I've never seen that with mine. So if you weigh the same bullet over a period of time does the weight vary by more than 0.1gr? I check mine with several check weights every 20 or so rounds and I have not noticed that kind of variance. I have one scale that always takes a few seconds to get to the final number though. Geeze I have the A/C going and sometimes a fan blowing on me when it gets a little warmer and mine always tells me my 50g weight is 771.6gr. I don't seem to have as much moon and barometric pressure issues. |
|
My Dillon is stored in a finished basement where I do my reloading. It is in a very temperature stable, low humidity environment and away from heater vents, not under an incandescent lamp, nor on a wobbly table. It stays solid as a rock to its accuracy potential. Every time I calibrate it with the 50 gram check weight on it she reads, "50.0 grams". Because grains is a smaller unit than grams (1 gram = 15.4323584 grains), I also switch it to grains and it reads "772.0". As 772 grains = 50.025 grams, I figure the check weight may be a bit over 50 grams or the unit may have a slight bias but it's repeatable to the unit's measurement accuracy. I've had it for 6 years and use it all the time. So far, so good. |
| OK, I am a sucker for cheap electronic scales, made in Red China of course. I have reached the point where I do not trust them. I always back check the readings with the balance beam scales. If you are doing some rough weighing, where 0.1 g up to 1 g repeatability is not required, they may be OK to use without a backcheck. If you are using them to weigh powder on finicky loads, best stay with something more reliable. |
|
I too work in the basement where there are no drafts and the temperature is stable but the scale manufacture recommends a 30 minute warm up period for the scale to stabilize… I normally turn on all the "normal" lights radio etc. about an hour before I start and it doesn't drift. First thing I do is the calibration routine. I was using it "cold" recently, unimportant stuff and found it did change by 4 to 8 grains as it warmed up. I also throw on a check weight from time to time. Frankly I really doubt that the Retail Price has anything to do with it. I would bet that CCW's China World special is as good as my $150 name brand… Assuming they are both set up and used properly. |
That's why I think my Dillon is so accurate. It has a 'Draft Shield' that surrounds the scale platform and it really cuts down on reading errors. |
| Your low humidity could be a problem. When I load in the winter I have static problems with my 1200 DPS. When I use it in the summer, I have no problem. You may need to wipe it down with a dryer sheet. Go to the website and read the trouble shooting guide. I sent mine back to the factory to find out my basement was too dry and was effected by static. |
|
After contacting Lyman, RCBS and Ohaus I have gathered the following information: Most of these scales use strain gauge technology. . Learn more on strain gauges at http://www.sensorland.com/HowPage002.html The strain gauge can give you good weighing results for weighing static loads, but can drift much more due to temperature variations which may occur by just by using the scale. Especially those with the feed motor (like the DPS 1200) which will generate heat just from being used. Zero often, and calibrate when suggested by the system. Any voltage fluctuation may confuse the electronics into thinking the load has changed These scales are VERY sensitive and will detect any movement which could cause the strain gauge to flex at all under it’s load (including the empty pan). Light drafts can be caused by the movement of your hand while loading the scale and will affect the reading, but should stabilize once the 'breeze' subsides. Test it – it’s cool! Any vibration of the scale will affect the reading if it causes the scale to move at all. Another fun test. AC Line noise will affect the scales, a line conditioner is an excellent investment. Fluorescent lights are not a problem unless they are close to the scale, in the 2 to 3' area. Cell phones can cause interference with electronics, all recommend that they be turned off if near the scale (10ft) Static charges will also make funny things happen - the used dryer sheets was a great suggestion that works. Both RCBS and Lyman have offered to evaluate the scales for me, I pay shipping, which I will do, and am grateful for since they are not brand new. These are great companies who stand behind their products and support their customers. You'll see get better performance, linearity and repeatability with an electromagnetic weigh sensor which cost a whole lot more, and takes us back to the “Does it really make a difference?” I have received a lot of feedback asking “What am I thinking and why worry about it so much?”. Well the answers are simple in my mind. The pursuit of perfection is why I got into the hobby of shooting, smithing and reloading. It’s fun to be able to make one hole. When I screw up and miss blow a group, I like to be able to prove to myself that the variation was the shooter (me) and not the other variables. For me this is fun. The other concern I have and wanted to understand is regarding loading pistol rounds where a tenth of a grain is much more of an issue than with my 25-06. My brother and I load 17 Mach IV (17 Fireball) and 460 Rowland cartridges which are by nature fairly hot and sensitive to load variation. A couple of tenths of a grain will make a significant difference. (If you haven’t shot a 460 Rowland in a 1911, you have to try it, Clark makes great barrels and they shoot great. http://www.clarkcustomguns.com/rowland.htm ) I have purchased an Acclab VIC 123 which reads to .01 grains and will continue this crazy pursuit of one hole groups !!! If there is interest I’ll write back later with more information and some statistical comparisons (GR&Rs for you quality geeks) of these measuring tools. Thanks to all who replied and contributed. This is a great community and I am proud to be a part of it. |
|
Good article for those having trouble with electronic scales- Ten Commandments for Electronic Scales |
| I have an older RCBS powder pro that I use. It is very accurate and easy to use, but can also be "flakey" at times. One thing I have noticed is that it is much more stable if I allow it to be "turned on" at least an hour before I use it. You do also have to calibrate these things occasionally. I have check weights. You should too, and make use of them. |
|
A comment about check weights. As these are used as a 'standard' to calibrate your scale against, you need to ensure that nothing happens to the check weight that will change it's weight. The obvious cautions include not letting it get dirty. What is not obvious, is that you should never pick it up by your fingers as you will transfer skin oils onto your check weight which will add to it's set weight. Always use tweezers to pick up the check weight to avoid contamination. I know, it sounds a bit anal, however, remember that you are trying to calibrate something that measures to 1/10 of a grain which is a 70,000th of a lb! |
Not from a single touch, but over time hand oil will build up on the weight. It may sound trivial, however, on a certain spacecraft program I worked on many years ago, we had some 'check weights' made from stainless steel that we used to calibrate an extremely accurate scale we needed for a very high precision balance measurement. Before we used them the weights themselves were re-calibrated by 1st cleaning them carefully with solvents and then running through a small thermo-vac chamber to ensure that all of the volatiles were 'boiled off'. Then they were checked to a 'certified standard' that was kept completely thermally controlled in sealed dewars in one of our class 100,000 clean rooms. |
Armory Sponsor