I am looking to caliibrate pin gages in house - if i measure them using a micrometer that has an acurate rating of 0.00005" - how do i determine the calibration level that my pin gages meet?

I am looking to caliibrate pin gages in house - if i measure them using a micrometer that has an acurate rating of 0.00005" - how do i determine the calibration level that my pin gages meet?

What is the rating of the pins? XXX or XXXX
We calibrate XXX to +/- .0001 and XXXX to +/- .000033

Coleman - check your micrometers - I believe you'll find that they read to 0.00005", but are only accurate to 0.0001". Then compare that to the accuracy needed for the pin gages - ideally your calibrating instument should be accurate to 10 times what you're trying to calibrate to. i.e. Calibrate an instrument used for +/-0.01 " with an instrument accurate to at least +/- 0.001"

Accuracy of the mics=+/-.00005"
Why do you want the accuracy of the device to be 10x greater than what you are calibrating?

Accuracy of the mics=+/-.00005"
Why do you want the accuracy of the device to be 10x greater than what you are calibrating?

Think of it in the "Blind leading the Blind" mindset. If I am calibrating a pressure gauge with +/1 psi accuracy with another +/-1 psi accuracy, what confidence am I gaining? In this scenario, I'm running a 50/50 chance. You want to increase your chances better than that.:)

10x is a good industry standard. You can go lower than that, but there are other factors you need to take into account. Have you performed any gauge studies to determine repeatibility?

I'm sorry my question was not very clear - I understand the 10% rule works i was trying to get a better understanding of how and why it is accepted as the standard.

I think you're seeking the answer that can best be described as the entire science of metrology.

Here's a good place to start:

(Fundamentals of Dimensional Metrology, Ted Busch, Wilkie Bros Foundation, Delmar Publishers, ISBN 0-8273-2127-9)

With regard to accuracy, Coleman do not confuse resolution with accuracy. I'm looking at the handout Mitutoyo provides with new 0/1.2" digimatic micrometers. Resolution is listed as 0.00005"

You are keeping environmental conditions constant aren't you - 68F as I remember for the standard. At the resolution you're seeking temperature variations could affect the accuracy of your readings.

Also, consider doing an MSA study - for info either search here or, get the MSA book from AIAG.

10:1 is ideal, but most labs use 4:1 as the minimum. As for your pin gages, you need to know what the tolerances (class) are.
XXXX = ±0.000005"
XXX = ±0.000010"
XX = ±0.000020"
X = ±0.000040"
Y = ±0.000070"
Z = ±0.000100"
ZZ = ±0.000200"
These tolerances are based on diameters less than 0.850" (if I remember correctly). The tolerances will then increase as the diameters increase. In our lab, we calibrate only class X or higher. We use either a Super Micrometer or a Laser Micrometer. All XX, XXX are sent out for calibration since we do not have the capability to check those accurately.

Well our requirement is that the pin checks the hole to +/-.001" so if i use a mic that is accurate to +/-.0001" than this is ok?
Also what is a super mic / Laser Mic?

Well our requirement is that the pin checks the hole to +/-.001" so if i use a mic that is accurate to +/-.0001" than this is ok?
Also what is a super mic / Laser Mic?
If you purchase any pin gage, you need to know the class. If you are using a pin gage from a "pin gage set" like .011-.060 inches, these sets are usually class ZZ. To check a class ZZ would be:0.0002/4 = 0.00005". So you would need a mic with an accuracy of ±0.000050" or better for the calibration.

Also, to check a hole to ±0.001", you would be better off using GO/NO-GO pin gage setup, were the GO pin is a postive tolerance, while the NO-GO pin is a negative tolerance. This keeps you within your mfg specifications with little risk of running out of spec.

We have an old Pratt & Whitney Super Micrometer that has been converted to use a laser instead of the old encoder. It has helped us in improving the accuracy from ±0.000030" to ±0.000010" or less.

For a Laser Micrometer, we use a Z-Mike 1210 Gold. It has an accuracy of ~±0.000030". It's calibrated using XXX pins with a limited range.