We use a chainsaw. There are lots of good books on amazon that will teach you how to make that cut.
Might be easier to just take logs to a local log home mill and let them pacman them for you. Prob wouldnt cost that much.
Wouldn't this require a 90-degree cut? Or am I misunderstanding the issue?
Well....Its 2 cuts that meet in the 90 degree corner. I bet a mill wouldnt charge you that much too run them for you. What is the diameter of the logs?
snap a chalk line down the center of the log vertically.....use this line to make your 45 deg. lines....cut the lines :)