How can I cut 4x4 posts that are already mounted?
It's common practice to set posts and trim them to height later. It's more difficult than you might think to set a post to a perfect height, and you don't always have the angles in advance..
Our strategy was to strike a line all the way around using a carpenter's square, then cut from all sides with a standard circular saw (four sides for level cuts, two for angles, or all four if you set the table angle). Be careful to hit the marks accurately. This leaves you with about a 3/4&quot; square or strip in the center that you'd cut with a hand saw or reciprocating saw.
If you do this carefully there's not much left to clean up. If you miss a bit you'll have some sanding to do.