I make walking canes from tree limbs fitted to their handles with a round tenon. Cutting straight, even tenon shoulders around my cane sticks used to be difficult until I discovered that an ordinary pipe cutter is perfect for the job. I clamp it to the stick and give it a spin to score a neat, clean shoulder line. I carve the tenon from there. The pipe cutter also works well for scoring shoulders on dowels. Give it a try!