You may have wondered how table and chair legs magically stay attached to the table, usually with no visible signs of hardware. In reality, it’s not magic at all that keeps them in place, but rather a simple device called a hanger screw, or sometimes a hanger bolt.
A hanger screw is a screw with no head. It is designed to be driven into wood or other soft material. There are wood screw threads on one end, which is pointed, and machine threads on the other. The two threads may meet in the middle, or there may be an non-threaded shaft in the center.
Hanger screws come in various sizes of threads, for example, 1/4 inch (.64 cm) or 5/16 inch (.79 cm). The thread length may vary from between 1-1/2 inches (3.8 cm) to 3 inches (7.6 cm). Installation generally requires the use of a special wrench.
The type hanger screw you’ll need will depend on the application. Table and chair legs, for example, must be attached firmly to the table, and would require a fully threaded screw, so there is no gap showing. Such projects would require a larger, thicker hanger screw, to support the weight of a tabletop, or in the case of the chair, the weight of an adult.
Hanger screws are generally available at local home improvement or hardware stores. In addition to table and chair legs they are used for a variety of other purposes. They may be used to build banisters, to attach the arms of chairs to the chair base, or to attach armrests to car doors. Any other application in which the hardware attaching two items must not be visible is definitely a candidate for a hanger screw.
The next time you visit your local hardware or home improvement store, check out the hardware aisle and take notice of the wide variety of screws available there. If you feel really adventurous, twist one of the legs off of your kitchen chair, and check out a hanger screw in action. Of course, be sure you return it securely, or someone in the family may end up on the floor!