With Any Axe equipped Woodblocks can be chopped from Hollow Log, Log, or Wood Pile. Each time a Woodblock is Chopped there is a chance to get a Knotted Wood Block instead. It costs 0.1-0.2 Phlegm for each Woodblock Chopped from a Log. With Any Axe equipped right-clicking a Woodblock and selecting "Split" will give you 2x Wood Choppings.