Counterbores - what are you using?

[TomG]

I can't think of very many reasons to counter-bore a threaded hole. Counter-bores are mostly used to sink the head on through screws, normally socket head cap screws. I have a four flute set that is 1/64" under, with nominal size pilots, for screws up to 1/2" diameter. That's pretty much all I use. For anything larger than 1/2", I would bump the size up to 1/32" over.

Tom