Michrometer

[blackthorn]

I got a mic at the flea market this morning. It is a Moore & Wright Sheffield. I paid $5. Good deal??

[Boerrancher]

I don’t think you got taken. Even a cheap mic will run $20+ new. Check a few different calibers of jacketed bullets with it, and see how accurate it is. If you are within 0.0005 you are golden unless you are a precise machinist who needs +/- 0.0001 or better.

[georgerkahn]

If you're elated with it, you surely did in fact get a great deal. I have a small handful of micrometers -- Starrett, Browne & Sharp, and Proto -- and, getting 100% repeat-ability of what you're measuring with 100% accuracy -- is the challenge. That being said, I generally "clean" my mic's faces by running a US one dollar bill through them -- just a bit on snug size -- and then check for zero. You did not indicate the size capacity of your new tool... I'm guessing 0 to 1"? If you're not too comfortable using it, there's a good Wiki basic tutorial at https://www.wikihow.com/Use-and-Read-an-Outside-Micrometer you may wish to view.
I wish you luck with it!
geo

[blackthorn]

Yes, 0 to 1". I have saved the website you recommended and will spend some time there this afternoon. Thanks!

[Alstep]

Only way to know the accuracy is to measure against a standard. Otherwise you're just guessing.

[EDG]

You can easily test your mike.

Close the spindle lightly on a clean piece of slick printer paper.
Lightly pull the paper from between the spindle and anvil.

Then lightly close the spindle on the anvil.

Your mike should read zero. If it is off use the adjustment feature to set it to zero.

To check other parts of the measuring range you can buy gauge pins or common bearing balls.
Since most handloading use is on bullets of .500" and smaller just having your mike set to zero is probably all you will ever need to insure accurate readings.

[country gent]

Here is how we checked mikes for certification. Zero mics gage blocks .100, .106,.112, .118. and .124 this shows out of square in anvils and small errors from it. Then .250, .500, .750, and 1.000 this showed wear in the threads on production tooling and mics used in a certain range. IE a mic used for years to measure parts at 3/8" may be good above and below but off due to thread wear at 3/8: range. Even thread wear can be adjusted out with the collet but localized is much harder to cure. On the production tools adjusting to low spot made it tight on either side of it.
Most mics are used evenly, and need very little other than setting to zero with your "feel" , not a big deal. Give your mics a good cleaning. with a soft cloth and brush. A cigarettes' paper between anvils. A light coat of insterment oil zero and use. For checking zeros standards are the way to go. measuring items like bullets drills or stock may not be accurate as manufactured items all have tolerences. Gage blocks or pins re held to much higher tolerances. The mics are your standard for measuring so they need to be set as accurately as possible.

[varmintpopper]

Country.Gent
I headed up a calibration shop that ran hundreds of micrometers through each month for certification, and we checked them exactly as You described.

Good Shooting

Lindy

[EDG]

I supervised the equipment purchase and set up of 2 metrology depts. during my 40 plus years in manufacturing and manufacturing engineering.

You are correct about the checking of mikes when calibrating them for use in commerce. Where the delivered products are expected to be produced with measuring equipment complying with NIST and ISO standards you have no choice. But be serious. We cannot expect anyone to buy $80 to $100 worth of gauge blocks to check a $5 mike. Offer the guy something inexpensive, practical and reliable. Something that is much better than nothing, because 99% of mike owners have no checking methods at home and manage to live with it.

[salty dog]

Check the faces for rust or crud, and check the zero as mentioned. If you want a little more checking, measure some feeler gages as a sanity check. You'll find that feel really matters. You want it firm but it's not a C clamp.

[JonB_in_Glencoe]

I don’t think you got taken. Even a cheap mic will run $20+ new. Check a few different calibers of jacketed bullets with it, and see how accurate it is. If you are within 0.0005 you are golden unless you are a precise machinist who needs +/- 0.0001 or better.

While I now have one standard (.250 x 1.000), I use to use Jacketed bullets.
For us castboolit measuring folks, using jacketed bullets as 'redneck' standards is plenty good enough.
When measuring soft metals, like lead boolits, be sure to use the slip clutch, assuming your mic has one.

[country gent]

In reality if you use the same set of Mics to measure every thing then even though they may be off a small amount They are your standard. If you measure the slug from slugging your barrel the cast bullets nd sized bullets with the same set then they are probably very close. All are the same as the mics were off the same for each.
In industry where a part, bullet bearing, or item has to fit with others made in other shops / factories is where being dead on zero is important. Weather mics calipers gages when working with things measured with different tools then the dead zero of them becomes important.
This one reason why the factory rifles are sloppier than custom built, tolerance must be maintained at a larger size to accommodate parts made in different areas of the factory or different suppliers. The custom builder measuring everything with the same tools and the same feel allowing him to tighten tolerances some.

[lostchild0]

Not to hijack but can feelergauges be used to check a mic?

[Randy in Arizona]

Not to hijack but can feelergauges be used to check a mic?

Slightly off topic, but years ago I would set the valve clearance on Fiats & Alfa Romeos.
I had about a dozen different feeler gauges and would swap between them until I had the right 'feel' for a clearance. Then I would mike the feeler gauge stack that fit. Most feeler gauges within a brand would be very close, but different brands might vary by almost a thousandth.

But the accuracy you need depends on your usage!

84

[DougGuy]

If you want to know an exact measurement of something, then a mic needs to be accurate and calibrated. If you just want to know is boolit A bigger or smaller than boolit B, or you slug a barrel then mic the slug, and you want to know if boolit A or B is larger than the slug then it needs no calibration whatsoever as it is then just a comparator.

I have one good Mitutoyo that came used from fleabay, I mount it in a stand for hands free operation, I often mic reamer pilots and reamers and it's really consistent and dependable. I know if a customer sends me some dummies and the dummies mic bigger than what gage pin will go into the freebore of a barrel, I know to inform him/her that the problem is with the sizing of the boolits and this allows me to spot a problem that has nothing at all to do with the barrel, but a sizing die needs to be addressed, maybe replaced, or alloy has grown as it has sat and age hardened. Either situation will make a round fail to plunk if it is close to freebore in size but now I know enough to describe the exact cause of the issue to my customer and I arrive at the decimal measurement from my mic that gets used every day and is repeatable and dependable, not how calibrated it is or isn't. So I use it as a comparator most of the time, even though if I mic a gage pin with it, it seems to be right what the pin says it is.

[DaveF]

While I now have one standard (.250 x 1.000), I use to use Jacketed bullets.
For us castboolit measuring folks, using jacketed bullets as 'redneck' standards is plenty good enough.
When measuring soft metals, like lead boolits, be sure to use the slip clutch, assuming your mic has one.

What JonB said.
I'm 74 years old and was born and raised in Yorkshire, England, with a machinist father. Moore & Wright were pretty much the standard then, and I still use a couple of their micrometers.
Unless they've been abused, they are fine for reloading.
You did well on the price.