Cutting Edge Tools for Cutting Tin

Modern snips make fast work of slicing sheet metal. Here are a few tools and tips.

Snips have come a long way since these Wiss-brand metal shears (shown in the photo above) were forged 100 years ago. Today’s tools are far easier to use.

In the not-too-distant past, people relied on the traveling tinsmith – also referred to as a “tinker” – to cut and repair most anything made of metal. But today DIYers have access to numerous tools, including metal snips, that allow us to do the cutting ourselves. Granted, cutting metal by hand with snips can be tricky. Workpieces can be stiff and difficult to maneuver, the edges you create during the cutting process are sharp, and the snips can often get in the way while you’re cutting. But take heart: By learning about different types of snips and practicing a few basic cutting techniques, you can quickly master working with sheet metal and duct work.

Snips of all sorts
A hundred years ago, snips resembled extremely beefy scissors forged from steel. They got the job done, but it took a lot of brute hand strength to initiate and complete the cut. Thanks to revised handle and blade designs, today’s snips make cutting far easier.

Because it can be difficult to create a curved cut in stiff metal, snips are specially designed to make the task easier, and a color-code system lets you know what type of cut the snip is built for:

  • Green — cuts clockwise curves
  • Red — cuts counterclockwise curves
  • Yellow — cuts straight lines

Snips are designed to make specific cuts. Green snips cut clockwise, red snips cut counterclockwise, and yellow snips are designed to make straight cuts.

Modern snips incorporate an additional pivot point into the levering action. These cutters (referred to as compound snips) drastically magnify your gripping force and allow you to cut 16-gauge sheet metal with ease.

Because they incorporate a secondary levering point into the handle design, compound snips provide greater cutting power without requiring more hand strength to use.

Compound snips (also known as aviation snips) come in two basic handle types: offset and straight. With offset snips, the cutting blades are positioned below the handle so your hand is above and away from the workpiece. Straight-handle snips have blades that are in line with the handles.

Offset snips’ handles are positioned above and behind the blades, keeping your hands away from the workpiece.

Cutting techniques
Now that you know which snips to use based on the direction of your cut, a few basic techniques will help you to conquer almost any sheet-metal-cutting task.

  • Straight cuts: Long straight cuts are best made with compound offset snips. Open and close the jaws of the snips completely to maximize the cut length. As you cut, one side of the sheet metal will tend to ride up and over the lower jaw. Roll this piece back and to the side as you go to keep it from getting in the way of your hand or from jamming the snips.

    When making straight cuts, bend the waste away from the snips as you work, and always wear gloves — cut metal edges are very sharp.
  • Curved cuts: Depending on the access you have to the workpiece, you’ll often need to use a combination of both left- and right-cutting snips to cut curves. If obstructions in a work area prevent you from completing a cut with one pair of snips, switch to the other and try cutting from the opposite direction.
  • Cuts in ductwork: When cutting round ductwork, there are a few tricks to keep in mind. If you need to make a cut in the middle of the duct, mark and cut the hole before snapping the ductwork together. Punch a starter hole into which you can insert the snips, and slowly cut along the line. If your cut reaches the duct’s thick locking seam, position the metal deep into the jaws before applying pressure. If, however, you only need to trim a bit from the end of a round duct that’s already snapped together, use curve-cutting snips.

    To cut holes in ductwork, start by punching a starter hole into which you can insert the blades of the snips; then slowly approach and follow your planned cut line.

The next time you need to trim some light-gauge metal, grab your trusty snips and go to it. With a little practice and the right tools, you’ll be able to cut metal almost as easily as paper.

This project is part of HANDY's Top 5 Collection: Metalworking Ideas & Tips.
Click here to check out the other four metalworking articles in this collection.