On Tue, 29 Nov 2016 16:47:56 -0700, "Bob La Londe"
wrote:

So... any words of advice on counterbores?

I see basically two types. Fixed pilot and interchangeable pilot.

The obvious advantage to interchangeable pilot is the ability to pilot
different size screw bores with different size head bores. They might also
be easier to sharpen with the pilot removed. Are there any disadvantages?

Are there any overwhelming advantages to the fixed pilot counterbores?


The big advantage of a fixed pilot is that if the pilot starts to
seize in the hole it isn't ripped free of the counterbore. So they are
great in production situations. For infrequent use the interchangeable
pilot offers you the option of having different size holes and a pilot
that fits them.
Eric