Birthday Project: Mailbox & Post

I got a text from our tenants on Friday night.  A guy was distracted driving and drove through our mailbox.


I went to the Home Depot to get a new mailbox and post.  The Mailbox was a semi-reasonable $17.  A wooden post was almost $40!  Ouch!.  They had some of the ugly metal posts for cheaper, but I didn't really like them.

So I made my own!

Materials: *
(1) Mailbox
(1) 4"x4"x8' Pressure treated Pine Post
(1) 1"x8"x2' Pine board
(4) #12 x 3" Countersunk wood screws
(4) #12 x 1" Pan Head wood screws
(1) Gorilla Glue
(1) High strength Concrete

* ' are feet " are inches.  You can remember this semi-easily by remembering there are more inches (doublequote) than feet (singlequote).

Credit:This chap made this helpful graphic for the screw types.  Thanks!

Cut List:
Cut the 4x4 to 5'10".  Save both pieces.  The long piece is the post.  The short piece is the cross bar.
Rip the 1x8x1 to 6 1/8" wide and 16" long.  Before you cut this, measure the recess on the bottom of the mailbox to make sure your dimensions match mine.  This piece should fit inside that recess.

I joined the Post (the vertical part) and Cross Bar with a half-lap joint and Gorilla Glue.  To make this joint, Mark a line 18" back from one end of the crossbar. Place a piece of 4x4 adjacent to this line, and mark another line on the other side.  These define the ends or "shoulders" of your joint.
To define the depth of the joint, find the center of the width of the 4x4 and mark the depth line.
I used a circular saw for the shoulder cuts and a 1" chisel to knock out the middle.  Cut another half-lap joint 11" from the top end of the post.  The two should fit together snugly, but not so tight that you need to beat them together with a hammer.

Fancy Bits:
You can make the post look better by adding some decorative touches.  One way to do this is to dog ear the post.  To do this, mark a line 1" back from the end of each end of the cross bar and the top of the post.  Set the Circular saw to 45°.  Now cut this angle following the lines you marked.

Alternatively you can make "Pointed" posts using the same procedure, just make the marks and cuts 2" back from each end.

The decorative work has some practical benefit as well.  This reduces the amount of water that can soak into the top of the post and rot it out.

I used Gorilla glue for this joint and two 3" screws to hold it together while the glue sets.  If you clamp it until the glue driest the screws aren't required.  That makes it look a little cleaner.  Gorilla glue expands as it dries, so be ready to clean up what squeezes out.  It's easy to clean up when it's soft, but a pain when it hardens.

Now center the  1x6 1/8"x16" mailbox mounting board on the cross bar approximately 1" from the post.  Drill pilot holes and attach it to the cross bar with two 3" screws.

I waited until the post was set to mount the mailbox so it didn't get banged around in the back of the van

Using Post hole diggers, dig  an 18-24" deep hole where the mailbox will be installed.  Drop in the post, add concrete, pack it in, and add water.  leave an inch or two of space below the ground so you can add dirt back to hide the concrete.  Remember to level your post!  I used a free level app for my smartphone since I neglected to bring one.

The USPS made this picture that shows how far back to mount the mailbox.  They also say to check with your local postmaster before you install the mailbox too.  My old box was too close to the road, and probably part of the reason it got knocked down.

To install the mailbox, drill pilot holes and screw in the 4 1" screws through the mounting holes in the bottom flange of the mailbox.

Here is the notebook page for this project.

Here is the finished mailbox and post.

I had the screws, glue, and pine board on hand, so DIYing this saved me about $30.