How to Choose, Cut, and Bend Sheet Metal

Thinking of building an enclosure for your latest project? Or maybe you’re working on a giant robot to terrorize the neighborhood? Chances are, sheet metal will play a part. Sheet metal comes in all manner of varieties and sizes. Here are some tips and tricks to help you get that shiny sheet into your desired shape.

Thickness

One of the most important decisions when working with sheet metal is deciding what thickness you’ll need. Similar to wire, sheet metal thickness is measured in gauges, with a higher number indicating a thinner sheet. To measure the thickness, you can use a sheet metal gauge, which will show you thickness in both gauge number and thousandths of an inch. One important note, however, is that ferrous and non-ferrous sheet metals of the same gauge have different thicknesses, so you’ll need one gauge for ferrous metals, and one for non-ferrous.

Bending

Bending sheet metal can be tricky, but with the right tool it’s easy. Those who work with it regularly are likely to have a sheet metal bending brake in their workshop, but this tool can be a bit expensive for the hobbyist. Thankfully, there are a couple of wallet-friendly options that can help you get the job done.

Using the edge of your workbench, a length of wood, two clamps, and a mallet, you can fashion a rudimentary bending brake. Mark a bend line and place the sheet metal on the edge of your bench. Next place the wood parallel and slightly behind the bending line. Clamp the wood on top of the metal to the workbench. Finally, bend the sheet up by hand to the angle desired. If you want a sharp 90° bend, tap along the crease with a mallet.

Cutting

Many different tools cut sheet metal, and each has its own strengths and weaknesses. Here are some of the more common tools, but they represent only a small number of options.

Snips

Commonly known as “aviation snips” or “tinsnips,” these scissor-like tools are great for cutting soft sheet metals such as tin, aluminum, brass, and thin-gauge (24 gauge or thinner) steel. Depending on the cut shape, you’ll use left-cut, right-cut, or straight snips, typically indicated by the handle color: red for left, green for right, and yellow for straight. Be sure to insert the metal fully into the throat of the snips for optimal cutting.

Hacksaw

A hacksaw can cut sheet metal, but its shape limits its turning radius and depth of cut. To prolong blade life, rub wax along the length of the blade. For a cleaner cut, put a strip of masking tape on the top and bottom of the sheet to keep chips from scratching the material.

Nibbler

The nibbler is a tool that offers a lot of control over the cut, but at the expense of cut width. Each cut punches out a tiny piece of the sheet metal, and the process is repeated. The nibbler shown here is hand-operated, though drill-powered, electric, and pneumatic versions are also common.

Jigsaw

A quality jigsaw and the correct metal-cutting blade will make short work of sheet metal cuts. If you need a straight cut, clamp a straight-edge to the sheet to act as a guide for the jigsaw footplate.

Band Saw

With the appropriate blade, cutting sheet metal on a band saw is fairly straightforward. Cutting metal requires slower blade speeds than cutting wood, but many band saws have multistep pulleys for changing the blade speed.

Cutting Aluminum with a Table Saw

It might sound crazy, but you can cut sheets of aluminum on a table saw. Make sure to use a 60-tooth (or more) carbide-tipped blade, and wax the blade to ensure the cut is well lubricated. Go slowly, proceed with the utmost caution, and wear hearing protection!

Deburring

After cutting metal, there’s often a sharp edge left. Be sure to remove it! You can buy a fancy deburring tool if you work with sheet metal frequently, but a quick once-over with a file is just as effective. Your fingers will thank you!