Quote Originally Posted by Richard Coers View Post
What I was trying to say is if you drill in 2" without clearing the chips, you can easily bind up the bit. I've drilled deeper than 4-6 with an extension, but you must clear the chips very often.
Richard, your experience of easily binding the bit and the absolute need to "clear the chips very often" doesn't seem to be universal.

I didn't read all the thread - have you tried the compressed air method? With a strong stream of compressed air directed behind the bit I don't have to stop and back out to clear chips. The air blows them out. No binding or excess heat.

But maybe it's apples vs oranges since something is obviously different. Speed of rotation, pressure, advance too fast or too slow? Bit sharpness? Perhaps it is the design of the specific bits I use that have more open space and let chips blow loose and not jam. Different bit design - knife edge, sawtooth? (I use carbide spur bits.)

Or maybe the wood makes a difference - the last time I did deep holes like this with an extension was for salt and pepper grinders in very dry cocobolo, dogwood, and cherry.