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crazy 20

WHEN PEOPLE SEE THIS BOX they say, are you crazy? Well, I don't think I'm crazy — I may have a couple of screws loose but that's about it.

Once you get the parts cut out for this project, it's all about taping, gluing and folding it together. Then you apply the finish and you're done.

Having said that, it should be noted that the parts must be accurately cut. Only then will it go together like it should. What will you learn from this project? More about cutting compound angles. I cut them using the same methods used for the lid of the Big Top project. The miter gets cut first, then the bevel. This saves you worrying about holding the parts safely in a table saw fixture or the miter saw. You can use the band saw to make the compound cut safely. However, I found that cutting the miters on the table or miter saw made the cut much cleaner. Cutting the bevels on the band saw isn't as critical, so go for it. And let 'em call you crazy. We know something they don't. I just don't remember what it is. Is that crazy?

Oh, and just for the record, a 20-sided, three-dimensional spherical box like this is called an icosahedron.

Tools needed

table saw or power miter saw

band saw

drill (“egg beater” style or handheld electric)

3/32″ (2mm) twist drill

Phillips screwdriver

60-, 100-, 120-, 150- and 220-grit sandpapers

No. 0000 steel wool

sanding block (see sanding block sidebar page 11)

random-orbit electric sander (optional)

Hardware & Supplies

10 No. 8-1½″ × 14¾″ (38mm × 375mm) wood screws

8 No. 6 - ¾″ (19mm) wood screws

12 6d finish nails

drywall spackling

paint color of your choice

Start by ripping several lengths of plywood to the width of the height of the parts. Then set the table saw's miter gauge to 60°. Cut the angle on the end of the ripped blank.

Set up a stop on the miter gauge's fence. This will require some trial and error. Each side of the triangles must be exactly the same length. When you've got this fine-tuned, you're ready to start cutting sides. After you've cut the angle on the end of the blank, turn it face down and push the corner against the stop. Keep doing this until you run out of material. Go to the next blank and cut more sides. You'll need 20 sides in all. I usually cut five extra in case I mess up. It happens to the best of us.

Here's one method of cutting the bevels on the sides.

Set your band saw fence to the correct bevel angle (see the illustration), make a sled that fits on the table and attach a fence at 30° to the fence of the sled. When you hold one side against the fence, it should line up the adjacent side as shown. You can then push the sled and the part past the saw blade. As an option, you can also use a power miter saw or table saw, but those large turning blades have a tendency to grab material when cutting bevels. You're cutting a compound angle one angle at time. In my experience, it's safer to make the cuts one at at time when working with small parts. If one of these little parts gets away from you, it opens up the possibility of injury to your fingers or hands. It's not worth taking a chance.

The first time I made one of these boxes, it took me a few tries to get the bevel angles just right so the box would fold up tightly. To test your cuts, cut five sides and put them together as shown above. Tape the joints and fold up it up dry. The inside and outside of the joints should close up snugly and the assembly should sit flat on your bench. You might need to make some fine adjustments. Make small changes: each change is magnified twice at the joint and, in this case, you've got five joints.

When you've got it all working, tape the box in the configuration shown in step 4. Turn the whole thing over and apply glue to all of the joints. Fold it together and add tape to the open joints. Obviously, you'll be gluing up the lid separately. It's a cool thing to see this whole thing fold up and come together. One second it's flat and the next it's a 15-sided box with a 5-sided lid!

The hinge is surface-mounted on the outside of the box and is painted to match the box. Finish-sand to 220-grit sandpaper. Apply primer that is compatible with the paint you'll be using. If you don't apply primer, there is a good chance the paint won't cure properly. Years ago, I was finishing a tabletop that I had made of MDF. After I shaped and sanded the top, I applied the colored finishing lacquer. The lacquer wouldn't cure and remained soft, even after I waited several days. I had to remove the finish and use the recommended primer first. When the finish lacquer was applied over the primer, it cured to a nice hard finish. Lesson learned the hard way. One other great thing about primer is that it has a lot of solids in it. After you apply a couple of coats, you can sand it using 320 grit sandpaper and achieve an amazingly smooth surface. If there are any dings still left, you can fill them with spackling, sand and apply more primer. Keep doing this until you like the way the surface looks. Then apply the paint. It will flow so smoothly, you'll be amazed. Top coat with a clear lacquer. Be sure the clear top coat won't wrinkle or react with the paint. Make a test piece to be sure.