30 Slot Mailbox Organizer

First graders can sometimes be hard on things. My wife wanted a mailbox organizer for her student’s papers in her classroom but didn’t want one of the carboard or particleboard ones that only last a year or two. So, of course, she talked me into building one. I built this mostly with plywood and a lot of reinforcement so it would not sag and hopefully hold up to a small swarm of 6 year olds.

The design utilizes lumber I had around the shop. My table saw sled was already set up for a ¼” x ¼” dado and I wanted to utilize that set up which is limited by the depth of the sled. That is why I went with the 3 piece back. (see fig. 1) It may be beneficial to others to modify the design to a one piece back. I also had to work with a height limit of 2 feet in order to fit under some other existing cabinets. I set up the design with a height of 23 ¾”, a cabinet width of 36” and depth of 11 ¼”. I cut the top to have a finished overhang of ¾” on the front and sides. (see fig. 2)

The casework is all plywood with ¼” thick edge strips cutfrom ¾” stock to finish the edges of the ¾” plywood. (fig. 3) On the ¼” shelves I used a 7/16” strip of birch with a ¼” relief rabbit cut into it with a router as a stiffener. (fig. 4) This will not only add strength to prevent sagging, but, will finish the front edge of the individual shelves. The other 3 sides of the ¼” plywood are captured in dados so there should never be any sagging.

The cutting dimensions for the ¾” plywood are as follows:

· 1 – 10 ¼” x 34 ½” x ¾” Bottom

· 2 – 11” x 23” x ¾” Sides

· 2 – 11” x 22 ¼” x ¾” Intermediate Vertical Supports

· 3 – 11” x 22 ¼” x ¾” Backs

· 1 – 11 ¾” x 37” x ¾” Top

· 27 – 10 ½” x 11 ½” x ¼” Shelves

With all the plywood cut, and my table saw dado blade and sled set to cut dados of ¼” x ¼”, temporarily attached a ¼” x ¼” piece of square lumber planed down from some scrap 2” parallel to the dado blade. (fig. 5) This will allow consistent and precise spacing of all the dados for the shelves.

Starting with the sides, I used the ¼” x ¼” spacer I just installed as a bump stop for the first dado at the top of the sides. (fig. 6) Since the top will sit directly on top of the rest of the box, this will provide consistent spacing for the shelves. I then placed the dado over the ¼” spacer and cut the next dado. (fig. 7) I repeated this process until I had cut 9 dados in each side, both sides of the intermediate vertical supports and the 3 back pieces. (fig. 8 & 9)

With all the dados cut, I needed to think about which parts needed to be finished and how to finish them. All I planned to do was apply a few coats of polyurethane to make for a smooth, durable and cleanable surface. I did not think it was necessary to finish the underside of each shelf since nothing would ever rest on it, but I also realized it would be extremely difficult to finish the shelves once the unit was assembled. To overcome this, I pre-finished all the shelf surfaces that would be difficult to reach after assembly. (fig. 10)

With limited surfaces in the ship to lay out the 8 pieces of ¾” plywood and 27 pieces of ¼” plywood that needed to be finished, I utilized some scrap plywood and cut dados into it utilizing the same method for the sides and back of the unit. (fig. 11) I then attached them to an empty wall space in the shop and used it as a drying rack. (fig.12)

I also made a single dado in some scrap ¾” plywood and inserted some ¼” plywood to work as a miniature saw horse to finish both sides of the intermediate vertical supports. (fig. 13)

It is now time for assembly. I started by taking one of the backs along with the two intermediate vertical supports and fitting them together with one of the top shelves. (fig. 14) With glue in the dados for strength, I shot 5/8” 18-gauge nails through the bottom of the ¼” plywood shelf into the ¾” intermediate vertical supports and the back at approximately a 30° angle. I also shot 1 ½” 18-gauge nails through the intermediate supports into the back piece.

I then installed either side with the top shelf in the same way angling the nail gun slightly to shoot through the intermediate vertical supports into the backs on either side of the assembled center section. (figs. 15 & 16)

With all 3 sections pinned together, it is just a matter of working your way up shelf by shelf. Each shelf is inserted into the slots and secured with glue and 5/8” 18-gauge nails. (figs. 17, 18 & 19)

I installed the bottom with glue and 1 ½” 18-gauge nails. (fig. 20) I then went over the intersections of the joints with a sander to level out any imperfections. (fig. 21) The top is then secured with glue and 1 ½” 18-gauge nails. (fig. 22 & 23.)

To apply the trim, I started by gluing and nailing the ¼” edge strips to the 2 intermediate vertical supports. (fig. 24 & 25) For the cleanest look, I left the strips long and cut them off with a flush cut saw after they were secured. (fig. 26)

The stiffeners were then cut to fit between the edge trim on the center section. They were secured into place with glue and ½” 23-gauge pin nails shot in at opposing angles. (fig. 27 & 28) The stiffeners were then installed on the two flanking sections. This is done before the edge trim because, unlike the center section, the trim can be easily sanded flush to the side for a very tight and clean fit.

With all 27 of the stiffeners installed, the edge trim is installed on the 2 sides, across the bottom and the top is wrapped with mitered cuts at the corners. I used wood filler to touch up the nail holes and fill in any hairline cracks at the joints. After it dried the entire unit was sanded smooth. (fig. 29) A few coats of polyurethane complete the project. (fig. 30)

Rod Gunter is the Executive Director at Gunter Building Solutions and has over 20 years of experience in the homebuilding and cabinetry industries. Rod has been responsible for building over 200 homes above the $500,000 price point. Rod has trained large groups including all the major home centers on selling skills, construction techniques and sustainable natural wood products. Rod resides with his family in Holly Springs, North Carolina. Gunter Building Solutions owns WoodAirGrille.com which produces wood return air filter grilles and wood return air vents.