Oak

function Chop()
	turtle.dig()
	turtle.forward()
	while turtle.detectUp() do
		turtle.digUp()
		turtle.dig()
		turtle.up()
	end
	while not turtle.detectUp() and not turtle.detectDown() do
		turtle.down()
	end
	turtle.forward()
end
function Cut()
	for i = 1, 8 do
	Chop()
	end
end
Cut()
turtle.turnRight()
turtle.forward()
turtle.forward()
turtle.turnRight()
Cut()
turtle.turnLeft()
turtle.forward()
turtle.forward()
turtle.turnLeft()
Cut()
turtle.turnRight()
turtle.forward()
turtle.forward()
turtle.turnRight()
Cut()
turtle.turnLeft()
turtle.forward()
turtle.forward()
turtle.turnLeft()
Cut()