I suggested the forstner bit only because I was not able to find a 2" auger bit. The plywood centering plate idea came from David Powell at timberwolftools.com. He also told me that the protool drill guide can handle a bit up to 2 1/2" with the centering plate removed. A co-worker of mine has the Hema Zb 20 drill guide and had a centering plate machined to fit his 1 3/8" auger.

I work in a timber framing shop that is equipped with a makita chain mortiser, but wanted to set myself for my own side projects.