Cutting metal flashing or sheet metal with tin snips need not be a bloody job, nor leave ragged, warped metal edges. A pair of leather gloves prevents bloodshed, and a few tips about the different types of tin snips and how to use them can produce smooth, accurate cuts.
Sheet metal snips come in multiple designs, but here are four snips commonly found in farm shops.
Tin snips, aka “bulldog snips,” are the forged, straight-jawed sheet metal cutters handed down from your grandpa. They make straight cuts well and can do limited curved cuts.
Aviation snips come in three designs: left, right and straight.
Left snips have red handles, are often marked with an “L” on the side of their jaws, and work well to cut curves to the left.
Right snips have green handles along with an “R” on the side of their jaws. They’re designed to cut curves to the right.
Straight snips can have black or yellow handles, are marked with an “S,” and can cut straight as well as gentle left or right curves.
There are strategies to get the best results from aviation snips:
- When making cuts with left or right snips, one side of the cut is the “waste” side and will tend to curl up and away from the cut. Even with straight snips, one side of the cut will be more distorted than the other.
- Avoid cutting all the way to the tips of a snip’s jaws. The tip of a snip’s jaws overlap slightly, which causes a pucker at the end of each full cut.
- Aviation snips have a small ramp built into the left or right jaw just ahead of the pivot bolt. The ramp lifts the waste side away from the cut and over the pivot bolt, making it possible to cut a curve while leaving the desired edge flat and unpuckered.
- When possible, cut near the edge of a piece of tin so the curled waste is narrow enough to easily manipulate away from the cut.
- Before attempting complex cuts with multiple curves or angles, trim away excess metal on the waste side of the cut so the waste area is narrowed and easily bends away from the cut.
- The jaws of snips should always be perpendicular to the surface of the metal. There is a tendency when cutting curves to lean the snip in the direction of the curve. This encourages the snip to “gnaw” the metal rather than cleanly shear it.
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