0.001 gram resolution iBalance 211

[bjld]

Hi all

After starting a thread comparing the GemPro 250 with an RCBS 10-10 I decided to buy an iBalance 211 from the same vendor as the GemPro 250.

It finally arrived from the US after 16 days so today I bought a 240 V transformer and set it up on a flat concrete pad on a bench next to my RCBS Chargemaster and another digital scale (0.1 grams).

It had two 100 gram calibration weights and after performing a linear calibration I put one of the 50 gram calibration weights from my Chargemaster on it.

With one of the sliding glass doors open (this is how I'll trickle loads up to weight) it read 50.002 grams and 50.001 grams with it closed (picture attached).

Although it's about triple the cost of the GemPro 250 it appears to have 0.001 gram resolution.

At the very least a good balance should have a dust cover on it when not in use and even better with the glass doors to keep wind disturbance to a minimum when in use.

I bought a set of check weights and I'll see what they weigh on a 0.0001 gram balance at work before giving the iBalance 211 a thorough test.

I'm picking up a new palma rifle and an f-class rifle this weekend and I can already picture myself reloading late at night with a pair of forceps to add or subtract that last single kernel of powder each time...

Is this really a good thing?

Regards
Ben

 

[mike in co]

one gram is 15.xx grains....
so that is xx.015 to xx.03 in my book......
still plenty good for reloading......
at three times the cost of a 250...you should be atleast .02 with .03 sensitivity...which is about what it looks like......
adding or subtracting a kernal is a powder size issue..........for long range large kernal...yes....
mike in co

 

[caroby]

Nice scale.... That'll give ya resolution...!

Wind (out on the range) will still drive ya mad..! Hehehe...

cale

 

[bjld]

one gram is 15.xx grains....
so that is xx.015 to xx.03 in my book......

Hi Mike

Since the scale doesn't weigh in grains suggesting the sensitivity is 0.015 to 0.030 grains can't really be substantiated.
It has two calibration modes: sensitivity and linear. I opted for linear because I'm far happier with a 3 point calibration, something the GemPro 250 doesn't offer.

The sliding doors really minimise the effects of air movement when in operation, no doubt significantly increasing the precision of the scale. And as I said in my original thread a precision scale really must have a dust cover when not in use.

I'm pretty happy so far. The result with the RCBS calibration weight is what I'd call a 3rd party quality control sample, something essential for checking a precision instrument. Once I've gone to work and weighed the check weights I bought I'll measure precision and bias at several points on the linear calibration curve. I'll use sample numbers of 20 or 30 at each point (exciting...) and give the results as bias (%) and coefficient of variance (%). I won't give es - it's likely to be 0.001 to 0.002 grams and doesn't mean the sensitivity is 0.03 grains. ;-)

Regards
Ben

 

[mike in co]

my comment was based on the lovely us of a...we use grains....so most will have no idea of what your machine can or cannot do...since we don't do grams....

just a communication point...

mike in co

 

[bjld]

Hi Mike

All the reloading data I use and record is in grains, even the data published by Australian Defence Industries (they might be called Thales now - make powders for Hodgdon, like Varget) in a metric country like mine. Geez, there might even be laws against using imperial measures here. The scale has several other units, just not grains, even though the vendor is in the us of a. It's pretty much six of one or half a dozen of the other.

I'll convert to grams by multiplying grains by 0.0647989, but only once because I'll write the answer against my existing reloading data. It shouldn't be a reason for others on this forum not to consider this scale if they're serious about long range shooting. It doesn't cost much more than the high end balances offered by Sinclair.

I'll convert the validation data I generate back to grains for you, but only to 2 or 3 significant figures. It might take me a while to get around to doing it because I'm going to break in the barrels of my two new rifles before I weigh the same check weights over and over again. I'd rather shoot groups than weigh groups! ;-)

Regards
Ben

 

[jdjframes]

Ben:

Perhaps you need such precision, but me thinks doing it that way won't be fun for long. If I thought I had to go to such extremes, I might hang it up.

There is a point of diminishing returns somewhere and you are pretty close to passing it.

But if that is your cup of tea, have at it and enjoy.

Jim

 

[Andy Cross]

Umm Calibration

Nice unit but you should have the option of setting the readout to grains if you need grains. One thing I learned in the lab a long time ago is you don't transpose calibration data unless you have to.

One thing you might not have considered is the variations in case capacity. An accurately weighed charge in a case with a slightly smaller capacity than the previous one will negate the effort in weighing that accurately. For a true measurement of each cases capacity you will need to take an accurate gas measurement. The gear for doing that will cost a lot more than the scales.
Andy.

 

[Boyd Allen]

Serious long range benchrest shooters are the main ones that tend to worry about powder charge accuracy to the milligram. Generally to be able to be read to .02 gr. a milligram (.001 g.) scale is needed, since each gram is equivalent to 15.4324 grains. I have a friend that has a scale that is accurate to that level. It taught me that my scales were not as good as I had thought, and how to be more consistent when operating my powder measure when loading at the range. Since I do not compete in long range benchrest, getting a scale of that accuracy is not at the top of my list.

 

[bjld]

The review of the GemPro 250 on the Accurate Shooter bulletin is what originally got me thinking about a 0.001g/1mg scale for weighing powder charges for long range shooting. I'm going to start weighing my charges to the nearest kernel again but I'm not going to go as far as weighing my primers.

2005 was my best year of competitive shooting. I had an RCBS 10-10 balance and it was sensitive enough to see the difference a single kernel of H1000 made. Maybe I had a hummer barrel, but I think it was more the attention to detail loading and my former wife being happy to see me go shooting every single Saturday. Practice makes a BIG difference. Sometimes I think people mistake practice for load development: "after shooting a couple of hundred rounds through my new rifle I found an accurate load". Shoot the same load another 100 times and your group sizes will probably shrink a little further.

After 2005 I bought an RCBS Chargemaster and gradually took shooting less seriously. I only went a few times a year and was happy just to be behind a rifle. Making ammo more quickly meant getting to the range. Then last year I began going more often (met another good woman who enjoyed time both with and without me) and wanted my group sizes to start shrinking, but they just wouldn't. So now I'm putting the effort back into brass prep and sorting them by weight. I don't sort them by capacity since the area under the pressure-time curve includes the volume of the barrel. This is considerably larger than the capacity of the case - think expansion ratio.

The area under the curve - integral calculus. Aah, if youngsters only knew how much pleasure mathematics could bring at work and play. In South Australia it's been removed from the high school curriculum. Junior scientists who reach for a calculator because they can't do long division in their head. Wasn't there a greek philosopher who despaired for the youth of his day? Some things never change...

I'll stop now - I bought 200 pieces of brass today that I've got to start sorting.
Ben