I have got to make up a couple of Oak bearing blocks for a ballast roller of mine. Nice easy job until it came to drilling the main shaft holes - that's when I realised that I don't have a bit large enough. The shaft is 65mm and the block is 100mm deep. I can get a 65mm forstner bit but from my experience they don't last long in oak. I was wondering if those adjustable auger bits are any good or if anyone has any other suggestions.