Two Micrometers Don't Agree

[M-Tecs]

The cynic would of course say that the vendors, having won with the lowest bid, sent the Grade B stuff.

Most of the items I purchased were local purchase. The exception would be the Starrett Dial Calipers. I purchased my first Starrett Dial Cal. in 1978 when I went to tech. school. I never liked it. Compared to a B&S it had no feel. At the time Etalon made them for B&S. Still use it today.

Later when I was purchasing for the shop I could get Starrett's thru the GSA stock system. Different pots of money so I didn't have to justify them. I still don't like the feel but they are robust and out of 30 your so purchased I never had one fail the initial cal. and only a couple had limited initial cal. so the GSA stuff did better that most.

I did local purchase three cased sets of carbide faced B&S mics 0-12" with zero limits on initial cal. Worst for initial cal. was Interapid indicators all local purchased thru three different sources. They tended to fail the full range test. They are still my favorite and I true don't care about full range since they are never used in that manor.

[JeepHammer]

I'm going with M-Tecs & Mr. Morris...

I'm also a BIG fan of Brown & Sharpe!
I have a lot of Starrett, which is accurate, but I buy Brown & Sharpe is my personal favorite.

At anvil (Zero) and 1" on a 1" micrometer you know it's accurate at anvil (which measures nothing) and at 1".
If you are measuring 1" pieces and nothing else, you know it's accurate.

When you check range of motion, you find the pesky details,
Pulled threads where some idiot used it for a 'C' clamp,
You find grit, crud, burrs & wear, particularly where it's been used to measure the same size parts thousands of times, wear at just ONE part of the scale.

There is a reason machinists keep their tools clean, usually in padded drawers, and LOCKED UP!
After I spend the money I do on extreme accuracy I don't want some floor sweeping knuckle head to use my micrometer for a hammer or 'C' clamp!
Or in my case, the idiot was using it as a ground clamp & 'C' clamp while stick welding 1" from the anvil!
(Ever REALLY want to kill someone? To the point you look around for 'Witnesses'?)

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If you are bending brass back into shape 0.0001" isn't a big deal.
0.0001" off in chamber headspace isn't a big deal.
If your total tolerance is 0.0001", an entire production run gets rejected.

To NOT have some kind of standard for a caliper doesn't make sense to me unless your measurements are 'Relative', like using a tapered throat case gauge adapter on a caliper.
Your 'Standard' is a case that fits your chamber, and you are just looking to see if your cases are +/- what fits.
A champfered/radiused throat on the adapter makes a direct reading impossible, so what's the point?

The campfer/radius makes the case insert/remove easier and doesn't mark the case, so all the adapters have champfered/radiused mouths... No direct read possible.

There is a reason I rotate the gauge standards, so I can find problems before they find me.
Using different standards in the range of scale finds those pesky problems that like to screw up my work pieces and make me start over with something properly QC'ed.

Not everyone is going to need extreme accuracy, so if Horror Fright is working for you, or a single standard is working for you, that's the tool for the job you are doing.

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The point was, the OP went beyond the usual 'Close Enough' measuring and ask about precise measurement issues,
To be precise, one or both micrometers are lying to him and he wanted to know which one, and presumably how to correct the situation...

I'm probably like every other machinist, when it fails QC it goes home for 'General Use', that includes reloading.
Still gets standard checks, still more accurate than Horror Freight, but won't screw up tight tolerance work at the shop anymore.
I also pass them down to newbies, guys working on 'Close Enough' projects like seeing if a shaft is going to fit a bearing or finding the correct size of stock to start machining... Grunt work...
He's learning to use one, so you KNOW it's going to get dropped, left laying around, beat up.

[uscra112]

As long as we're expressing opinions......My chest has had mikes of all sorts of brands over 50 years. Ones I like stay, others drift away. The preponderance after all that time is "vintage" Brown & Sharpe. Never could warm up to Starrett. "Fit & finish" of their mikes just never measured up in my view. I have Starrett steel rules and squares and a 12" dial caliper, but their mikes joined the throng that emigrated. There's one mechanical-digital Fowler mike near the bench lathe, which I admit to using pretty often due to my weakening eyesight. But when it comes to "tenths" the B&S rules, even though I need a magnifier to read it.

[JeepHammer]

Yup!
Lights & magnifiers, comes with tri-focal glasses that make you look like a chicken bobbing it's head around everytime you focus on something...
I'm nearsighted, so I often loose my glass on top my head, probably spent 100 hours 'looking' for my glasses over the years.

When I got the last inspection table, I got the BIG remote readout!

[GONRA]

GONRA's "Go To Mike" is a Sears 1" Craftsman from 1950's High School Days.
Have fancier stuff, but it verks Just Fine for usual Slam Bang machining we all do.