Thanks SplinterGroup... originally I was going to use an Onsrud spiral up bit but then decided it would be better to use my laminate flush trim bit. I wanted to make sure the hole for the bit was as perfect to the input output tangent point as possible so I marked up and drilled it. Then sawed out and perfected with a chisel. I didn't think about using a core box bit. Sounds like a good option for sure.