Well, if you want to cut wood with a 'sledgehammer', you'd need some wedges; or, you could get a half-sledgehammer/half-axe tool which around here is known as a "splitting maul".
Of course, Merve's taken us on a tangent again; ahundiak's post was regarding "green metal fenceposts" which are commonly known as "T-posts" and an axe doesn't do much but get dull chopping on them. Come to think of it, a sledgehammer would bounce most of the time, and if you had 'nuff gumption to "demolish" said T-post, it'd still be a big hunk of metal that would be more of a pedestrian/vehicle hazard than ever.
Of course, the EL's the place for tangents, right?
