How to Make Wood Curve

Construct a steam box for the wood pieces meant for curving. The steam box contains the wood pieces and connects to a boiler, usually a gas can or tea kettle, so steam flows through the box continuously. Nail together four 2 by 8 pine boards to form the body of the steam box with two open ends, using the nail gun to nail through the ends of each board into the side edge of another board. Work with one connection at a time and apply a strip of wood glue between the pine boards before nailing them together.

Saw a square of wood from the fifth pine board and saw away one corner. Glue and nail this piece to one end of the box so the end contains the hole from the missing corner, which will allow the entry of a hose for steam.

Stuff rags into the other end or saw a door out of the remaining pine board as long as it does not seal air-tight. Optionally, drill holes in the long sides of the box and run hardwood dowels through the holes to build a rack inside the box. This gives the steam room the ability to surround all sides of the wood and fully treat it.

Fill your boiler with as much water as possible since steam bending wood only works if the wood is exposed to plenty of steam constantly for an hour per 1-inch of wood. Adding more water during the process does not work, and if the steam flow experiences any interruption at all, the wood pieces must be removed and left for 24-hours before repeating the process.

Attach a heat-resistant hose to the spout of your boiler and stick the other end of the hose into the hole on the wooden end of the steam box.

Place the boiler onto a hot plate and plug in the hot plate to begin heating the water into steam. A camping cooker works as well, but the open flames in an environment such as a wood shop may pose a danger.

Insert the wood pieces for bending when the steam box is fully running and filled with flowing steam. Usually, it is wise to also include a test piece of wood from the same stock with the pieces meant for use to check for readiness for bending.

Remove the wood pieces after the proper amount of time, which should be an hour for 1-inch of thickness. Try to bend the test piece, and if it snaps instead of bending, return the other pieces to the steam box for exactly 10 minutes longer, and no more than that because you can "overcook" the wood, according to David Smith at the Lulu website. Overcooking the wood refers to leaving it in the steam box too long, which allows too much moisture and structurally weakens it.

Clamp one end of each wood piece in place then bend the other end just past the desired curvature and clamp it in past as well. Try to bend wood the direction it naturally wants to be bent and leave it clamped in place for 24 hours before removal and usage.