Two-Tier Unknot Corner Shelf

two-tier unknot corner shelf

A friend asked me to build this two-tier unknot corner shelf as a Valentine’s Day gift for her husband. She specifically knew the shelf she desired and clearly described its design. The project was to be built with no hardware and install easily without a hundred screws damaging the wall.
two-tier unknot corner shelfI took a day or two to think about the project and decided to build a prototype of the shelf using a two by four. I drew a schematic of the shelf on a scrap paper and transferred the measurements to the lumber. I also constructed a corner jig out of plywood. The jig keeps everything square and provides something solid to clamp to as the glue dries. With the unit complete I experimented with various ways to install it. I placed a mirror hanger on the back of each vertical support, but with no support in the corner the unit was unstable and drooped away from the wall. After much thought and experimentation I discovered the easiest and strongest support was a mortise in the shelf and a tenon attached to the wall.

two-tier unknot corner shelfThe shelf was to be a blond color with a matte finish. While visiting the wood store the decision was made to use ash wood. I purchased a beautiful piece of 5/4 ash lumber  7 1/2″ wide and 8′ long; enough lumber for two complete shelves. The lumber acclimated in my workshop a few days and it was planed to an inch thick. I proceeded to (1) crosscut the length of each section. With all six sections cut to length I (2) cut 45 degree miters for the left and right sides. (3) Each section was then ripped to 3 1/2″ width.  (4) A stacked dado blade was used to make a 1/2″ dado across the back of the top  shelf sections. Pieces of ash were glued into the ends of the dado to create a mortise.

two-tier unknot corner shelfI waited for the glue to dry and (5) cut the corner miters on the top and bottom shelf sections. I considered various ways of strengthening the joints of the assembled sections. In the end the use of biscuits was the victor. Using a power biscuit jointer I cut biscuit mortises into the surface of each joint. Working one at a time each joint was glued with a biscuit and clamped. Gluing and clamping requires patience and scrutiny to insure each connection is square in every direction.

I waited a day for the glue to set and then started the finishing process. Using a random orbital sander I sanded every surface with 80, 120, 180 grit sandpaper. The sharp ninety-degree corners and edges were slightly rounded with the gentle touch of a cabinet scraper and a sanding block. Rounding the harsh corners provides a luxurious surface to touch and allows for a durable finish.

I applied three to four coats of polyurethane finish by hand, lightly sanding between applications.  The polyurethane finish hardened over a duration of few days and then sanded with steel wool to reduce the glossy appearance.  A super silky feel and rich luster was created on the finish by buffing the surface with rottenstone. I am happy with the complete piece. At my friend’s request I delivered the shelf days before Valentine’s Day. The photos with the books are of the shelf installed in their home.

Because I made two of these shelves I have another currently stored in my shop. Maybe I’ll install it in my home or perhaps someone will be interested in purchasing it from me. Either way, it’s a win. And please be sure to have a Happy Valentine’s Day!

two-tier unknot corner shelf schematic

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