Router-bit drip edges
You can use a dovetail router bit to shape a drip edge that’s just right for all sorts of situations. For example, to protect a square post base against end-grain rot I used one of these bits to cut the drip edge shown in the drawing. The angle cut by a dovetail bit is steep enough to shed water, but shallow enough to be strong. When I cut a drip edge on a post, I allow some offset between the bottom of the post and the drip edge. This allows me to insert any shims without dinging the edge.
Emanuel Jannasch, Chester, None
Edited and Illustrated by Charles Miller
From Fine Homebuilding #39
The sketch as shown is fine for pure gravity (downward) loading, and the drip edge method shown should work as long as the concrete base quickly sheds water.
However, it is not a great detail for posts that may be subject to uplift or lateral loads.