How do I build a simple wooden box with strong corners?

A box is the best first project in woodwork because it contains almost every problem furniture has — corner joints, a floating panel, grain matching, squaring an assembly, and a lid that has to fit — at a scale where the timber costs very little and a mistake takes an hour rather than a week.

What you'll need

• A board wide enough for the sides, or four pieces
• Thin ply, solid wood or MDF for the bottom
• A saw and a means of cutting the corner joint
• A router or saw for the bottom groove
• Band clamp or clamps and glue
• Hinges and a catch if the lid opens (optional)

Step by step

1. Cut all four sides from one board in order.Mark the board across before cutting so you can keep the sequence. Assembled in that order and flipped as needed, the grain runs continuously round the box, which is what makes a plain box look considered.
2. Choose the corner joint honestly.A rebated corner is quick and adequate for a light box. A mitre reinforced with splines or keys looks clean and is strong once keyed. Finger joints and dovetails are strongest and most decorative and need the most practice.
3. Cut the corner joints on all four corners before anything else.Doing the same operation four times in one setting is what keeps them consistent.
4. Groove all four sides for the bottom.A groove near the bottom edge, the same distance from the edge on every piece, sized for the bottom panel. Cut it before the corners go together — reaching into an assembled box is impossible.
5. Cut the bottom panel to size, allowing for movement.If the bottom is solid timber, cut it a couple of millimetres narrower across the grain than the groove distance, so it can shrink and swell in the groove. Plywood or MDF can be a snug fit.
6. Dry assemble the whole box including the bottom.Check it closes, check the diagonals, and check the bottom sits in all four grooves. Have the band clamp already set.
7. Glue up, but do not glue the bottom in.Glue the corner joints only. A solid bottom must be free to move in its grooves; gluing it in splits either the bottom or the sides. A plywood bottom may be glued if you wish.
8. Check square and flat before the glue grabs.Diagonals across the top of the box, and sight across the top edges for twist. Correct now by shifting a clamp.
9. Level the outside when cured, then cut the lid off.Plane or sand the corner joints flush. Then saw the lid free by cutting round all four sides at the same height — a table saw with the blade set just under the thickness, then a knife through the last fibres, or a careful hand saw against a fence.
10. Clean up the sawn edges together.Rub the lid and the box on abrasive stuck to a flat board, keeping them in their pairs, so the joint line closes perfectly. Mark the back edge of both so they cannot be reversed.
11. Fit hinges and any catch last.Small brass butt hinges recessed into the back edge, or box hinges with a built-in stay. Mark from the box, not from a measurement.

Tips

• Making the box as a closed cube and sawing the lid off afterwards is the technique that guarantees the lid matches the box exactly. Making them separately almost never lines the grain up.
• Line the inside with felt or flocking if it will hold anything delicate. Do it after finishing.
• Chamfering or slightly rounding all the outside edges makes a plain box feel finished and takes ten minutes.

Common mistakes

• Gluing a solid wood bottom into its grooves — The bottom changes width and the box sides do not. Either the bottom splits or the box is forced apart at a corner. It floats, always.
• Cutting the grooves after assembly — There is no way to run a groove round the inside of an assembled box cleanly. It has to be done while the sides are flat.
• Making the lid separately from the box — The grain will not match, and the fit at the joint line will never be as good as a lid sawn from the assembled box.

Questions people ask