How to install barrel nuts in our daily life

The barrel nuts come with a zinc plating to prevent rust. Sometimes this coating builds up inside the threads at the plating facility. Before trying to install fasteners in your bench, thread the bolts fully in and out of the nuts a couple times to test their fit. As with any mechanism made from metal, a couple drops of oil will help lubricate the threads and ensure a smooth installation. We bias the fit tolerance on the nuts a bit tight so they hold well. Don’t be alarmed if you can’t thread them by hand at first. A few cycles with a wrench will loosen them up. Your leg and rail joinery should be cut and ready to assemble. A short stub tenon is sufficient.

Drill a ½” hole through the leg using a drill press (if possible) for the bolt. For looks, you can counterbore for the washer and bolt head if you want it recessed into the edge of the leg. Position the hole so it’s centered on the rail in both directions. Barrel nuts work well in material no thinner than 1-3/4”. This allows you to leave enough material at the bottom of the barrel nut hole so its not visible from the front of the rail. But if your rail is thinner and the barrel nut hole needs to go completely through the rail, it’s fine.

Next, assemble the workbench base (clamp it if possible, or brace it against a wall or bench) and use a long ½” drill bit to drill the hole in the end of the rail.
The hole in the leg acts as a guide bushing so the hole goes straight into the end of the rail.
Drill an inch or so at a time at most, backing out frequently to clear the shavings. Drill as deep as you can. If you need to go deeper (depending on your particular leg’s width and drill bit length) remove the leg and continue drilling the rail only.

To find the position of the barrel nut hole, you’re going to use the position of the hole you just drilled as a guide.
Place a bolt deeply into the rail and carry the position of the exact center of the bolt up and across the mortise and just onto the face of the rail.

Next, place a straightedge on the mark, sight from above, and line it up so it’s dead parallel with the bolt. Mark a line against the straightedge.