After building an oak bookcase with adjustable shelves that were 3/4 in. thick by 11 in. wide by 36 in. long, I found that the weight of magazines and books made the shelves sag noticeably. I could have made the shelves thicker or added thick edging at the front, but I liked the look of the thinner shelves. I decided to try embedding steel in the shelves.

After experimenting with various types of steel stock, I found that square, hollow tubes—1/2 in. by 1/2 in., inset along the front and back edges—worked best. Steel stock like this is available at hardware stores and home centers.

To embed the tubes in solid-wood shelves, start by ripping 1/2-in.- to 3/4-in.- wide strips off the front and back edges. If you’re using plywood shelves, prepare solid edging of the same size. Next, center dadoes in the edges of the shelves, sizing them to fit the square tubes. The fit should be snug along the top and bottom of the tubes, but a little loose side to side so the tubes don’t inhibit you from gluing on the edging tightly. Also, cut the tubes a bit shorter than the shelves so you don’t hit them if you need to trim the ends of the shelves. Drop the tubes into the slots, adding some yellow glue to keep them from sliding one way or the other. Then glue on the front and back strips, using cauls to line them up so you have a minimum of planing to do afterward.

The steel tubes reduced the sag under a fully weighted shelf to less than 1⁄16 in., and you’d never know they are in there.

—RICHARD ROSS, Longmont, Colo.

Illustrations by Dan Thornton
From Fine Woodworking issue #302