I have not used the longer ones to bore deep holes. The long bit is too long to fit in my machines. But I have a bunch of through mortices coming up, 16" deep, I will come up with some plan at that time. I think I will bore as deep as the shorter bits will go, from either side and then switch over to the longer bits or hit it with the chain saw.
I know I can sharpen the Irwin bits, but the wood owl is in question. daiku, how do you address the sharpening of these bits?
