Hmm, interesting idea. I didn’t think of that way to be honest, I don’t have a ton of experience with D-bits so they don’t pop to the front of the idea line for me. I was also wanting to maintain maximum peripheral contact inside the hole so as not to enlarge the threads at all, and I felt that the two minimally-sized gullets would get me debris room but still maintain my best contact inside the hole. I bet I’ll think about a D-bit next time though, thanks for planting the spark.I was just wondering why you put gullets on the tap, instead of milling the side, kinda like a D-bit.