The Octabox

Is an eight-sided box twice as complicated as one with four sides? Not this one. As far as measuring goes, the OctaBox is easier to build than a rectangular box. On the OctaBox, every side is the same length and the top and bottom are identical—in fact, there are only two different parts to make for the whole project.

Making the two halves fit perfectly together isn’t complicated, either. I used a really clever system (see The Easy Way to Make a Lipped Box at bottom). It worked great, but my execution was flawed: I made the box upside down! Granted, the top and bottom look alike, so what’s the difference between them? Not asking that question while building the box is how I got into trouble.

I wanted the box to have a deep lid, so you could use it as a receptacle for discarded shells or candy wrappers. I also wanted the lid to be narrower than the base, so when assembled the box didn’t look top-heavy. So far, so good.

I goofed somewhere else: The lips are reversed. On the vast majority of boxes with lipped edges, the lip on the lower half sticks up. Mine doesn’t—it’s recessed. You didn’t notice? Neither did I, until someone pointed it out just before this article went to print. I’m not sure that it really matters, so I didn’t get upset; I just laughed. I was tripped up by the project’s simplicity—not complexity—and built it so fast that I overlooked a subtle detail. The plans given here are for the box just as I made it, but I’ve included alternate plans for making the box the “right” way.

I did learn one important lesson: Flying by the seat of your pants can be dangerous. When making a box, draw a cross section before you begin and keep track of which side is which!

Choosing wood

You don’t need much wood to make an OctaBox, so you won’t have to spend a lot to buy something special. I used cocobolo, a brightly colored exotic wood that’s relatively easy to work. I looked for boards with straight grain so all the pieces of the box would look pretty much the same.

You’ll need 1/2″ material for the sides of the box (A) and 1/4″ material for the box’s top and bottom (B). The most convenient way to obtain this wood is by ordering it over the Internet. It usually comes in pieces that are 3″ wide and 24″ long. I’ve dimensioned the box so you can get all of the side pieces from one 24″ board and all of the top and bottom pieces from two 24″ boards. However, I strongly recommend that you make or order at least one additional piece of each thickness for testing your setups. (This wood could be any species, of course.)

I milled my own lumber for the box and cut the pieces 30″ long. This additional length helped quite a bit when cutting the side pieces (Fig. C) because I had more support for the last cut. Bottom line: 24″ will work, 30″ is better.

Make the sides first

Before we get on the road, let’s look at a map. You’ll be making the box as a single unit, then sawing it apart into two pieces. You’ll be making lips on these pieces so they nest together, and that’s where you’ll start—with the lips.

Rip the 1/2″ thick piece 2-5/16″ wide, then joint both edges to yield a piece that’s 2-1/4″ wide. Install a 1/4″ dado set in your saw and cut a groove the length of the board (Photo 1). Cut the same groove in one of your test pieces. Ideally, you’d use a special set of blades or a single blade that cuts a flat bottom, but a standard dado set will be OK. (It will leave some unobtrusive scoring marks that you can’t easily remove—flat-topped blades won’t.) Turn over the piece and apply a finish to it (Photo 2). In addition, draw a slanted line down the full length of the side without the groove. This orientation line will enable you to reassemble the pieces in the correct order after they’re cut apart in the next steps.

Cutting the 1/2″ piece into segments is a two-step pro-cess (Photos 3 and 4; Fig. B). The bevel cuts must be right on the money, so it’s worth the time to make test cuts first. (You can use any wood for this. The angle is correct when eight pieces form a tight-fitting octagonal frame.)

Tip: Make a dedicated sled for cutting both the box’s sides and the top and bottom parts. While you could simply use a miter gauge and a fence, the sled has a number of advantages. First, there’s no tearout, because there’s zero clearance around the blade. Second, you can easily mount toggle clamps on the sled to prevent the parts from moving—and to keep your hands out of harm’s way. Third, the cuts are absolutely straight because the sled runs true, without any wiggle.

Tape the segments together in the correct order and glue them together (Photos 5 and 6). Level the top and bottom edges of the box with a jack plane or by rubbing the box on a full sheet of sandpaper taped to the top of your tablesaw. Before moving on, mark the location of the groove on the outside of the box (Photo 7). This is very important. Once you’ve glued on the top and bottom of the box, the groove will be hidden. You’ll need to know exactly where it is when you saw the box apart.

Add top and bottom

To save time, you could make the box’s top and bottom from single pieces of wood. It’s risky, though: They might crack. Gluing the pieces all around restrains them from expanding and contracting in width with changes in humidity. My solution is to minimize this movement by making the top and bottom from triangular segments, forming a “pinwheel” (Fig. D). The pinwheel’s grain doesn’t run in a single direction—it rotates with each segment.

Sawing these segments is exacting work (Photo 8). The 45° cuts must be precise. As with the side segments, the best strategy is to make test cuts, adjusting the fence until you can make a complete pinwheel with tight joints, right off the saw. I had to reposition the fence on my sled a few times
to accomplish this. Even so, I had to shim the last piece of the pinwheel before cutting it in order to tweak its angle just a smidge.

Once you’re set, rip and joint the 1/2″ material so it’s 2-5/8″ wide. If your wood is only 24″ long, leave a blunt end on the first segment in order to obtain all eight pieces (Fig. C). The last segment will have a blunt end, too—but it won’t matter (Fig. D). Tape and glue the segments into two halves (Photo 9), then tape and glue the halves together. Sand both surfaces of the pinwheels until they’re flat and even.

Place the box’s sides on both pinwheels and trace around them (Photo 10). Be sure that the pinwheel “spins” the same way for both top and bottom—it’s easy to get mixed up here. Remove the waste using a bandsaw, staying about 1/8″ away from the line. Glue the top and bottom onto the box. You don’t have to use clamps, just weight. A gallon can of paint works well. Trim the top and bottom flush with a router (Photo 11).

Bevel the top and bottom (Photo 12). This cut is fussy, too—you don’t want to take too much or too little. It’s best to make the first round of cuts a bit shy of the goal, then adjust the blade and fence in small increments.

Separation time

The next step is to cut the box apart. To succeed, you’ll need to know the exact location of the groove you cut in the first step. Of course, it’s hidden inside the box now—but you marked it on the outside of the box, right? It’s not easy to set up the saw from this mark alone, however—you’re much
better off using the pieces you made for test cuts (Photo 13).

Mark the location of the new, outside groove on the 1/2″ thick piece. Cut a short test groove in this piece (Photo 14). Ideally, the top of this groove should exactly line up with the bottom of the inside groove. However, this might result in a fit that’s too tight. (The box’s lid must fit in eight different
positions!) It’s better to cut the outside groove an additional 1/64″ deep, which will result in a slightly looser fit. Adjust the fence so the grooves are separated by a whisker of wood.

Saw all the way around the box (Photo 15). Put tightfitting filler pieces into each groove as you cut—they’re essential for keeping the box intact as you cut it apart. Tape the pieces in place. When you’re done, separate the
two halves by scoring the outside groove with a thin knife. Bevel the lips by planing or sanding, then test the lid’s fit all eight ways. If it’s too tight, use a rabbet plane or sandpaper to adjust the fit. Sand and finish.

The Easy Way to Make a Lipped Box

First—what is a lipped box? It’s one that has a stepped rim all the way around the lid or the base, enabling the two pieces to nest together. The lip provides a tight seal and aligns the two pieces. If the box isn’t hinged, a lip is essential. There are many ways to make upper and lower lips—here’s an easy method that automatically results in a good fit. The directions below are for the box I actually made, but if I had to do it over again, I’d reverse the positions of the two lips and make a thinner lid. See Fig. E, for a better design.

 

---