Calibration Standards - Rod Standards vs. Gage Blocks

[aliasJohnQ]

If a company just has rod standards which is used for large micrometers, can that be used for other things during the calibration process?
Or does gage blocks take the cake?

[Jennifer Kirley]

Long Island Indicator Service has posted a calibration instruction that contains good information about what to use for calibrations of micrometers, etc., and how to go about it. I am not affiliated with Long Island Indicator.

The first issue with using rods is their traceability to NIST. Is that established?

The second issue is sensitivity. Are they calibrated with a 10:1 resolution or better? That is a general "rule of thumb" when using transfer standards to do an accuracy check.

The third issue is the recommendation to check calibration over a measurement range. This can be done by wringing gage blocks together - can you do that with your rods?

These three considerations are in general why I do not personally recommend calibrating with a rod, though a pin such as Deltronic may be part of the process IF it's kept quite safe from wear and damage.

How big are we talking about? I used to wring together gage blocks to calibrate 12 inch micrometers.

[Hershal]

First question is: Used on what? If they are for large mics which is normal for end standards, there are few other things that have similar requirements such as calipers and so forth.

Second question: What is the uncertainty of the cal of the end standards? That will help determine if you can use them for anything else.