Over the weekend i installed a new pellet stove for a friend. He has a Amish made log home with 18-20" logs and i needed to drill a hole through one of them. I used a 6" hole saw and began on the inside log i drilled and drilled and in between chiseled until i had about 5-6" inside the log. Then i replaced hole saw drill bit with a long drill bit (22") and made a hole all the way through the log until in exited the log on the outside of the house. Then i went outside and did the same thing using the drill hole i made as a guide for the holesaw. This worked good but it took forever after getting that side in 5-6" i got a small chain saw and finished the job by removing pie type slices from inside the hole. Finally i seen day light and i finished the hole with the 6" holesaw and it cleaned it right up nice even hole all the way. Insatlled wall thimble but had to use a piece of stove pipe due to the large log and short wall thimble. It's all hooked up now but i gotta tell ya the things we do for our friends.