Most efficient? Brick.
Can usually be found for free, works fast, flat enough, gets a nice toothy edge. If you need to flatten, just find another brick.
(half joking, half not - sidewalk is a really fast way to fix a broken tip)
Can usually be found for free, works fast, flat enough, gets a nice toothy edge. If you need to flatten, just find another brick.
(half joking, half not - sidewalk is a really fast way to fix a broken tip)