Pin gauges.
"surftom" wrote in message
...
How do I *accurately* (n.nnnn) measure very small hole diameters?

I can poke them with a numbered drill but that would only get me close by
"feel" and only if the hole was a standard size. e.g. measureing a .0431
hole is kind of hard with a vernier or mic

No real reason - enquiring minds just want to know

Tom