If your curbside mailbox is beat up and it’s time to replace it, you might be elated to find that a replacement plastic mailbox is less than $5 at the local home improvement megastore. You might be not so elated to find that the replacement mailbox does not fit onto the post that is left behind.
A cheap solution is to make an “adapter” using a 1×6 board. The cheapest 1×6 board I have found is a fence picket, believe it or not. It costs less than two dollars at the same home improvement megastore. I marked and sawed off a piece that fit flush into the bottom of the new mailbox. I then took my hole saw kit and matched a 1 3/4″ hole saw that fit just over the end of the old mailbox post. After cutting the hole, I placed the board onto the mailbox post, and marked the two other screw holes that were on my post. Your post will be different so do what makes sense. I drilled those out with a 5/16″ drill. I also took the drill and sort of hogged out a shallow recess into each hole that the bolt head could go down into, so the bolt head would be flush with the board when attached and the mailbox would be able to sit flat on the adapter board. Attached the adapter board to the post with some 1/4″ screws and nuts. Marked and drilled the holes that would attach the mailbox to the adapter board, and then attached the mailbox using 1/4″ screws, nuts, and large washers. Put the nuts on the inside of the mailbox so that if you need to replace the mailbox later, they won’t be corroded and force you to cut them off. Then again, if you have had problems with your mailbox being stolen, maybe you want to JB Weld those nuts on there instead…
Ta-da! New mailbox. And it only cost me 5 bucks if some kids decide to smash it…