The Aluminum Bending Brake

An aluminum bending brake is a hand-powered machine that is used to bend metal or aluminum into simple or complex shapes. There are two basic types of sheet metal and aluminum bending brakes, the cornice brake and the box-and-pan brake.

The cornice brake is the simpler of the two types. It has one clamping bar that runs the full width of the machine. Therefore, it can make only straight bends that go the entire width of the workpiece. However, in some applications this is enough. For example, the creation of simple ducts can be done on cornice brakes that have open-ended designs so that the completed duct can be slid off the end of the machine.

A box-and-pan brake has a clamping bar with a number of removable blocks. The blocks can be removed and rearranged so that small areas can be bent, as can areas of pieces that have already been partially formed. This type of aluminum bending brake can be used to create more complicated pieces such as boxes and pans, and even pyramid shapes. After the aluminum is bent, it can then be riveted, soldered, or otherwise fixed in place.

Aluminum and sheet metal bending brakes are available in smaller models that are more suitable to general carpentry applications where only small quantities of aluminum have to be bent at one time, and the bends may all be different. There are also larger aluminum bending brakes that are suitable for jobs where large amounts of metal have to be bent for a particular job, such as guttering or siding.

Sheet metal bending can be boiled down to three basic bends: the L, the J, and the U.

A simple L bend is typically a 90 degree bend. It can be used for a number of applications, such as hiding the end cut from vinyl soffit material or covering the underside of a piece of foam insulation at the beginning of siding jobs. An L bend can be made with other angles, too, for forming things like a center of a section of valley flashing. L bends are quite handy for giving a nice, finished look to formed aluminum or sheet metal pieces.

The J bends form a hook profile, just like the letter J. On many bending brakes, it is easiest to make the short part of the J bend first.

The U bend is the most common bend used for capping door and window trim. The U bend, as its name suggests, requires two bends on the same side of the coil and is simple to make. sometimes two U-bent pieces of metal are used to cover posts. In these cases, a larger U covers three sides of a square post, and the smaller U is placed in front like a cap.

Another fundamental bend is a hem. The L, J, and U bends create pieces with sharp edges. For a cleaner, more finished look, or in places where the edge of a piece of metal may come in contact with a person, a hem helps tremendously. To make a hem, you make a half-inch bend as far as the brake will go (usually 120 or 130 degrees). Then you flip the piece, and crush the rest of the bend flat using the brake's jaws.

As for the best setup for a sheet metal brake, it is partly a matter of preference and partly a matter of the job at hand. Some people set up the brake across saw horses with a piece of plywood across the same sawhorses behind the brake for storing the pieces yet to be bent. Sometimes the workbench can be put in front of the brake so that there's no walking around the brake to fetch pieces and other equipment. Some put a workbench behind them as they are facing the bending brake so they can go from cutting to bending by simply turning around.

There are all kinds of extra equipment and tools you can get to go with a sheet metal bending brake. People with a large job ahead where many pieces must be the same size may benefit from a coil slitter. But for people doing ordinary bending where every piece is likely to have different dimensions, a slitter can be too much trouble to haul out to a job site. Foot pedals are also available for aluminum bending brakes, but users say that they are best for jobs where bending of heavy aluminum, such as grade 3003-H14, is required.