Build a Knockout Knock-Down Desk

An elegant, five-piece base stores compactly and assembles easily with interlocking joints.

When a friend learned that she’d be moving to Connecticut, via a year of research at Princeton University, it was clear that she would need an easily transportable desk. She asked me to design one with a simple Danish Modern feel, a spare, functional style that became a popular genre of Mid-Century Modern design. The desk I came up with combines clean, contemporary lines with traditional joinery. It’s extremely sturdy when assembled but surprisingly easy to take apart for moving–exactly the features my friend wanted. The key to this combination of strength and convenience is precise, interlocking joinery. 

As shown in the photos and drawing, the base breaks down into five parts: a pair of leg assemblies and three stretchers. While the leg assemblies are constructed with traditional mortise-and-tenon joints, the stretchers are simply pressure-fit into place. Lap joints can be extremely strong if they’re well made. 

The desktop can be made of anything practical: solid wood, a veneered panel, or plywood covered with plastic laminate. The last option is what we used for the desk shown here, and I ordered standard white Formica for a true Mid-Century Modern vibe. The base is built from black walnut for contrast. The desktop is fastened to the base using four 21⁄2" washer-head screws that are driven in counterbored holes near the end of each top stretcher.

The base goes together with snug-fitting lap joints–no fasteners are required. Notches in the top stretchers interlock with notches in the top rails of leg assemblies. A single bottom stretcher joins the rear legs with dovetail lap joints. The top and edges of the desktop are plastic laminate, applied to a substrate of 3⁄4" plywood and 1⁄4" plywood backing strips.

Basic construction sequence

  • Build leg assemblies.
  • Cut stretchers and lap joints.
  • Make the desktop.
  • Fasten the top to the stretchers.

Leg assemblies go together with mortise-and-tenon joints

I rely on my mortising machine for cutting mortises, but you could also do this work with a plunge router, and use a chisel to square each mortise end. I transfer the mortise thickness to the rail ends with a marking gauge. Then I set up a stack dado in my tablesaw to cut the tenons. Rather than risk making tenons too thin, I usually allow for a small amount of paring with the chisel to get tight-fitting joints.

Make multiple passes. Guide each rail against the miter gauge, and use the tablesaw’s fence as a stop when cutting tenons. Several passes through the stack dado complete each cheek cut. The fence also aligns top rail shoulder cuts.
Mark shoulder cuts. Hold the top rail tenon over its mortise to lay out the shoulder cutline. 

Tap together. It’s smart to test-fit all joints before final assembly. You’re ready for glue-up when joints need to be tapped together with a rubber mallet.

Compare diagonals. Test for square as each leg assembly gets clamped together. If diagonal measurements aren’t identical, rack the assembly slightly until they are.

Stretchers join leg assemblies with two kinds of lap joints

The lap joints that connect the three stretchers to the leg assemblies need to be snug, in order for the fully assembled base to provide a solid work platform. That’s why I final-sand the leg assemblies and stretchers before cutting these joints. Any significant sanding after completing the joints can loosen the fit.

This part of the project involves both hand-cut and machine-cut joints. I do the handwork first, making the dovetail lap joint that connects the bottom stretcher to the rear legs. For complete step-by-step details on making this joint, see “Joinery Class” (page 66). Whether I’m cutting joints by hand or machine, accurate results depend on exacting layout work. With lap joints, I never measure and mark. Instead, I align the parts exactly as they will intersect and mark against the intersecting edges with a sharp pencil or my marking knife.

Align shoulder cuts. Center the completed bottom stretcher on each top stretcher, then mark the inner shoulders of top stretcher lap joints. Position top stretchers where they will lap over leg assemblies to complete your lap joint layout. 
Aim for a mallet fit. Test-fit and pare the joint until it can go together with a few light taps from a rubber mallet.

Cut kerfs, then chisel clean. Because of the cutting depth and precision required, I forego the stack dado and kerf out the waste for each lap joint with a finish-cutting blade. With the stretcher held against the miter gauge, I cut just inside the layout lines and clean up the bottom of the joint with a chisel.

Eyeball the alignment. The laps in top rails can be cut just like those in the stretchers, guiding the workpiece against the miter gauge. Get the two shoulder cuts exact, then quickly cut between them. Test the fit of each joint, and shave off a little extra if necessary.

Plastic laminate makes a durable, attractive work surface

This desk could have a solid wood top, but plastic laminate (often referred to as Formica) is in keeping with the Mid-Century Modern style that inspired the spare, functional design. If you go with laminate, use 3⁄4"-thick, cabinet-grade plywood as the substrate; it’s stronger and lighter than particleboard or MDF.

I glued and nailed 2"-wide strips of 1⁄4"-thick plywood along the outside edges of the panel to give the top thicker proportions. I also installed  1⁄4"-thick strips where the top rests on the leg assemblies and as backing at the ends of the stretchers. These details are shown in the drawing on page 51.

Tips for installing plastic laminate

  • Get surfaces smooth and clean before glueup.
  • Cut laminate carefully. Allow about 1⁄4" of overhang around the substrate. Use a laminate-cutting blade and make sure to support the thin material close to the blade, to minimize chatter during the cut.
  • Apply a thin, even layer of adhesive to both surfaces. A small brush works well on laminate strips and substrate edges. A straight length of scrap laminate is a good spreader on large, flat surfaces. Smooth away ridges and thick spots.
  • Never join laminate to substrate when the adhesive is still wet. Wait for the glue to dry; it  shouldn't come away on your finger.
  • Do edges first. Attach and flush-trim two parallel edges of the desktop, then the remaining edges, then the top.
1. Coat both surfaces. Spread a uniform coat of contact cement on the laminate and the substrate.
2. Roll it on. When the adhesive is dry to the touch, press an edge in place and roll it flat using a roller tool.

3. Trim all around. With a flush-trim bit in a trim router, remove the excess laminate along both long edges and at the ends.

4. Align over dowels. Use 1⁄4" dowels to separate both tacky surfaces while aligning the laminate to overhang the plywood evenly. Dowels can be spaced about 12" apart. Remove one dowel near the center, and press the laminate in place with a roller. Remove adjacent dowels, and roll down the laminate, working toward the ends. Give the top a thorough rolling before you flush-trim with the router.

5. Join base to top. Drive four 21⁄2" washer-head screws in counterbored holes. Locate holes 4" from top stretcher ends.

Manage messy wires with desktop grommets

Today’s assortment of office equipment can easily create an unsightly mess of wires and cables. Desktop grommets can help you tame the tangle. If you’re a woodworker, you probably have what it takes to install grommets in desktops and countertops made from wood, plastic laminate, or solid surface material. 

Your first task will be to select the size, style, and color (or finish) of your grommets. Woodcraft stocks a good basic selection of grommets; go online for more. The simplest grommets are small circles of plastic designed to fit in 11⁄2"-dia. holes.  For extra convenience, you might want to consider an “active” grommet that incorporates an electrical outlet, along with one or more USB ports (see photo at right).

When installing grommets, don’t be fooled by the flange

No matter what size or style, a desktop grommet usually has a liner that fits inside the opening and a flanged top edge that’s designed to cover the opening. You could cut a grommet opening with a jigsaw, but this leaves a rough, uneven edge that will look terrible should the grommet be misplaced. Then there’s the risk that the grommet flange might not completely cover the opening. For best results, cut grommet holes with bits rather than blades.

Rout perfect circles with a baseplate jig. To make clean, accurate holes for larger grommets, a pivot pin in the router baseplate creates an easy-to-use circle-cutting jig. If you don’t want to make your own version, consider buying the Jasper baseplate jig, which will cut circles from 1" to 71⁄2"-dia., in increments of 1⁄16" (inset photo).

The Jasper baseplate jig is designed for use with a plunge router and a solid carbide, 1⁄4"-dia. upcut bit. Adjust the router’s depth stops to complete the hole with a series of 1⁄4"-deep passes. Before you start, make sure to mount a temporary backer block on the underside of the desktop with double-stick tape.

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