Sheet Metal Brake

A sheet metal brake is a machine for making straight, accurate bends in sheet metal. The sheet is clamped between a bed and a clamping bar, and a hinged bending leaf (apron) swings up to fold the metal along the edge of the clamp. Brakes are central to metal roofing and flashing work, where long, consistent bends are needed for drip edges, valley flashings, rake and fascia trims, coping caps and custom panels.

Types

• Portable brakes (often called siding brakes in North America) are lightweight aluminium-framed units carried to the job site and set up on stands. Lengths of about 8 to 10 ft (2.4 to 3 m) are common, allowing full-length trim and flashing to be bent on site.
• Cornice brakes have a solid clamping bar for long straight bends and creases, suited to high-volume shop work on standard profiles.
• Box and pan (finger) brakes use removable clamping fingers of various widths, so pieces with existing flanges can be bent into boxes, pans and complex flashings.
• Magnetic brakes clamp with an electromagnet, leaving room to form enclosed shapes.
• Press brakes, powered by hydraulics or motors, bend heavier gauges with punch and die tooling in fabrication shops.
• Mini brakes and hand brakes, around 4 ft (1.2 m) long, handle short pieces on the roof.

Capacity

A brake's capacity is rated by length and by the thickest material it can bend, and ratings depend on the metal: a brake rated for aluminium may be overloaded by steel of the same gauge. Supplier guides note that a 22-gauge aluminium-rated brake would struggle with 16-gauge steel.

Good practice

• Protect painted surfaces with clean clamping faces and, where needed, protective film.
• Respect minimum bend radii for the metal and coating, especially in cold weather.
• Mark and measure from the clamping edge for repeatable bends.
• Use accessories such as slitters (to cut strips from coil), hemming bars and return gauges.

Brakes complement hand seamers, snips and roll formers in the metal roofer's kit.