Checking Micrometers For Accuracy

[insanelupus]

I am not a machinist by any stretch of the imagination. My calipers and micrometers (I use the micrometer a lot more than I ever thought I would when I started casting several years ago) are Chinese products. The primary use for both is strictly for handloading (measuring COAL, bullet diameters, slugged barrels, chamber mouths, etc.).

At the moment I don't have any of the gauge blocks to check the micrometers for accuracy, they are on the shopping list. Are there any home/every day type items which are consistant enough to check a micrometer against (my first thought was possibly a bright shiny new nickle though the round edges aren't nearly as convenient to measure as a square block). Trying to test accuracy down to .000" or so sounds very silly to try and do with an every day item, but curiosity has gotten the better of me.

If there is, I figured someone on here would know. Thanks.

[imashooter2]

Feeler gauge.

[GRUMPA]

In the industry we went with both extremes when it came time to calibrate our mic's. In other words if we were checking 0-1" mic we would use gauge blocks. For the do it yourselfers Feeler gauges are fine, but if you want to be really precise just order "gauge pins" to check. We would check say with a .100 pin AND with a .900 pin to get accurate readings on the 0-1" mic's. You may want to do a quick google search for DELTRONIC GAUGE PINS for whatever size you want.

[insanelupus]

Ahhh, I'm a bone head, I never even thought to break out the ol' feeler gauges!

[Calamity Jake]

For all our calibration needs I use gage blocks and or ring gages, in a pinch I have used
Deltronic pins.

A guick check for "O" on your mic is to close the mic on a piece of paper then pull out the paper
this cleans the anvil faces, close the mic and check for "O", if it reads "O" then caliberation is
good 99% of the time

Deltronic corp. is the cats meow for gage pins but there also expensive. I would suggest going to mscdirect.com and look at there cheapest gage pins, order single pins in a size
from about .125, .250 and .750 these will allow you to check your mic and calipers.
If you order pins get the minus tolerance pins, meaning the pin is accually .0002 smaller
than the size etched on it(.250 pin is .2488).
If you want true to size pins then you will need to get the Deltronic pins.

[WILCO]

Are there any home/every day type items which are consistant enough to check a micrometer against....

Drill bits.

[John Boy]

I use certified ISO plug gauges that also have a multitude of other uses

[Doc Highwall]

I have both gage blocks and pins. The pins get a lot of use checking case mouth diameters before and after sizing along with cylinder throats on revolver's.

[wallenba]

Bracket a group of pin gauges for rifle calibers you are interested in or have (+ and -). Order them from a tool supply company. Then you can check rifle bores as well as check your mics.

[Casting Timmy]

I agree with Wilco, measure some drill bits.

[deltaenterprizes]

A good quality J word bullet should be real close, Sierra , Speer, Hornady come to mind.

[Reverend Recoil]

I purchased four shop grade gauge blocks between 0.250" and 1.000"on Ebay for $5. I have used them to calibrate several micrometers and calipers to 0.0005".

[Dutchman]

google: micrometer standard


http://www.google.com/search?tbm=isc...h+Images&gbv=2

[Cap'n Morgan]

The shank of an end mill will be from .0001 to .0005 below nominal size and is probably the most uniform non-gauge, gauge stock you'll find. Most metal shops will trade you a handful of broken or worn-out cutters for a six-pack.

[atr]

we used to have "joe-blocks"....small square blocks machined to a specific thickness with the decmial thickness stamped on the block.....we checked useing them.. you might be able to pick us some from a machine shop

otherwise, I think the drill bit method is as good as any

[R.M.]

You need to be aware that gauge pins come in plus, and minus. The minus are kinda like a go gauge, and the plus like no-go. They're a tenth or two under for minus, and the same over for plus. This is because a .500" pin that's .5000 will not fit in the same size hole. The pin needs to be ever so slightly under to slip in.
Most gauge pins we get are of the minus type.

[uscra112]

'nother source for gage pins is www.gageshop.com. They have Meyer Gage pins for $2.50 each.


Last time I ordered they had a small set of gage blocks on sale for under $40.00, too. I bought 'em. OK, they're "offshore" make, but plenty good enough to check micrometers.

Phil

[Rio Grande]

You need to be aware that gauge pins come in plus, and minus. The minus are kinda like a go gauge, and the plus like no-go. They're a tenth or two under for minus, and the same over for plus. This is because a .500" pin that's .5000 will not fit in the same size hole. The pin needs to be ever so slightly under to slip in.
Most gauge pins we get are of the minus type.

yes and no.
You are correct, a .500 pin will not go in a .500 hole.
But all pins, even the most precise, have tolerances. It is not a bilateral tolerance.
It is the direction of the tolerance that is referred to as "plus" or "minus". That is, a .500 basic size plus pin might be .500 or larger (within it's stated tolerance class). A .500 basic minus pin might be .500 or smaller (within it's stated tolerance class).
Deltronic pins are very useful as they come in .0001 increments and are very precise. For instance, you could use a .4998 Deltronic pin to check that .500 hole, allowing clearance for fit.
This is from the Deltronic Certificate of Accuracy attached to the .500 pin set...."Deltronic Corporation unconditionally guarantees each gage herein to be within a size tolerance of plus .000040" (.001mm) minus nothing..."

[Rio Grande]

we used to have "joe-blocks"....small square blocks machined to a specific thickness with the decmial thickness stamped on the block.....we checked useing them.. you might be able to pick us some from a machine shop

otherwise, I think the drill bit method is as good as any

Drill bits are definitely not consistant in size enough to check a micrometer.
'Joe' blocks, so named from their inventor Swedish machinist Carl E. Johansson, certainly are.

[Flinchrock]

Drill bits are definitely not consistant in size enough to check a micrometer.
'Joe' blocks, so named from their inventor Swedish machinist Carl E. Johansson, certainly are.

I absolutely agree 100%,,,I AM a machinist.
Anyone can use whatever method they want to calibrate their measuring tools, but your product is only going to be as good as your measuring tool, it don't cost that much to do it right! what the heck,,,we're only playin' with fire here!

drill bits,,,sheesh