Manual nibbler, punch-and-die typeA nibbler, or nibblers, is a tool for cutting sheet metal with minimal distortion. One type operates much like a punch and die, with a blade that moves in a linear fashion against a fixed die, removing small bits of metal and leaving a approximately 6 mm wide. Another type operates similar to tin snips, but shears the sheet along two parallel tracks 3–6 mm apart, rolling up the waste in a tight spiral as it cuts. Nibblers may be manual (hand operated) or powered.Power nibblers are often powered by, though electrical types also exist. A common nibbler tool is an attachment, which converts the rotary motion of the drill into a reciprocating motion of the jaw.
Nibblers are the perfect tool for cutting across corrugation as well as circle cuts around vent pipes ect. The only downside to a nibbler is that they are specialized tools and only used in metal cutting. You may want to opt for the attachment shown above if you don’t plan to get into the metal roofing business. Blade Cutting.