I was reading a post on the forum the other day and was impressed with the posters ability to measure to .0001. I thought to myself Holy crap he must have some very accurate measuring tools. There was a picture included and the dial indicator was in the picture. I thought to myself I want one of those that goes to the 4th decimal point, and right now. So I blew up the picture as large as my computer would allow to get the model number, and to my surprise the manufacturer of the indicator had printed right on the face of the indicator that it was only capable of .001, or 3 decimal points of accuracy not 4 so how does this poster get the extra accuracy he is claiming? Is there some dial indicator guru like SParker with scales that fixes them, or something I don't understand? Please help I want the .0001 so I can make the best ammo I possibly can.
The ability to measure
- Thread starter ebb
- Start date
Seems to me that wanting FOUR decimal places is WAY too fine a distinction and that MANY other influences on group size are FAR more important.. It's sort of like this guy--meaning me--spending a kilobuck on a V4 Autotrickler/300 to get to two decimal places of powder charge when I'm still at about 3 on the 10-scale of shooting skill.
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Any variable that you can eliminate, should help on target.
Being able to measure better than 0.001" while a little anal takes that measurement out of question.
Many throw money at it.
But refuse to take the time to sort primers.
Time is too expensive.
Being able to measure better than 0.001" while a little anal takes that measurement out of question.
Many throw money at it.
But refuse to take the time to sort primers.
Time is too expensive.
Doug Beach
Silver $$ Contributor
Lots of .0001” indicators out there. Mitutoyo, & Interapid are a good place to start.
Interpolation can be useful, depending on the performance of the measuring instrument.
For example interpolate this mic reading from a recent post.
For example interpolate this mic reading from a recent post.
On a micrometer I tend to agree with the halfway in between, but some thing digital I am not so sure. Something digital in my opinion needs to be checked against a known gage at least twice a day. If you believe in 5th place decimals I think you are deluding yourself. When I worked at P&W I don't remember seeing any EMDs or prints that went beyond the 3rd place. Most of the blade and vane EMDs were to the 3rd place at 10 times scale. I will talk to Andy one of my engineer friends that was there when I was and check with him and make sure I am right. I've got a DRO on the milling machine that is a type of digital measuring device and I can see more hesitation the slack in the leed screw can account for, then the next pass totally different. I do not have near the faith in the measuring devices and many of you do. I would like to hear what Jackie has to say on this subject.
The question I would pose is that do you really need to measure to that fine of degree when you consider all the variables in reloading components, environmental conditions affecting shots on target and the limitation of the shooter's skill.
Maybe bench rest guys need to do this, I don't know since I never participated in that discipline nor ever had the interest or mental makeup for it.
Maybe bench rest guys need to do this, I don't know since I never participated in that discipline nor ever had the interest or mental makeup for it.
I generally call a minus a cold one, a plus a hot one, about a half - a half being hot or cold of the target. I just don't get all that excited about it when it comes to reloading. I look at weights as 1/10 of 1/7000 of a pound, or even 1/2 of 1/10 of 1/7000 of a pound, to put it all back in perspective, for myself at least. Fortunately, I don't have to work on stuff with the micron level type sizes and finishes, if reloading had req'd that, wouldn't have ever started with it.
dgeesaman
Gold $$ Contributor
I have micrometers that read to the .00005 inch and are accurate to .0001.
I also have a Sartorius balance that reads to the .005 of a grain. (<1 milligram).
While the micrometer resolution might be useful for sorting bullets it’s overkill for everything else. Likewise .01gr resolution is barely meaningful considering powder kernels are .02 to .05grains each.
Feel free to overindulge in measuring accuracy but it almost never shows on target.
I also have a Sartorius balance that reads to the .005 of a grain. (<1 milligram).
While the micrometer resolution might be useful for sorting bullets it’s overkill for everything else. Likewise .01gr resolution is barely meaningful considering powder kernels are .02 to .05grains each.
Feel free to overindulge in measuring accuracy but it almost never shows on target.
Everyone will determine the edge of a hole diffferent. You cannot see to .001" so how could you measure it by eye. The micrometer may be accurate to 0.001' but your eye isn't. More BS. I was at the Super Shoot once and if several scores were close they had 3 experienced guys measure the same group. Every group you shoot with the same load will measure different. I eyeball with my digital micrometer where I think the edges of the hole are and it's more than good enough. Wanting more is dumb and OCD.
i should have said caliper not micrometer. You use your eyes and personal judgement as to when the jaws match the hole.
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Fast14riot
Gold $$ Contributor
Dial indicator, you can infer how close to the next indices you are, great for comparative readings. Digital, you are only sure of the programmed rounding, leaving you one decimal place less accuracy than shown.
DR_2297
Silver $$ Contributor
Just because an instrument has a certain resolution does not mean that the repeatability is there nor the reproducibility of the measurement in the process. Rule of thumb is to use an instrument with 10X the resolution of the tolerance being sought. There is inherent error in the measurement tool and process.
So… if you are attempting to measure a .001 tolerance your instrument should have a .0001 resolution.
Anyone that says they are measuring at the .0001 or smaller increment without being in a controlled environment is just wishfully thinking.
So… if you are attempting to measure a .001 tolerance your instrument should have a .0001 resolution.
Anyone that says they are measuring at the .0001 or smaller increment without being in a controlled environment is just wishfully thinking.
Groups are not measured with a micrometer. A caliper is an eyeball guess.
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