When I first became interested in electric trains as a hobby, I noticed the construction of a lot of parts was pretty simple. I wanted to replicate some of it myself. But I quickly became frustrated at paying $4 for a tiny sheet of brass and ruining half of it when I cut out my part. Here’s how to cut thin metal at home without wasting half of it.
The tools for cutting metal vary depending on the type of metal, but generally speaking, you can use relatively simple and inexpensive tools to do it, including a paper guillotine, electric metal shears, a nibbler, a rotary tool, or hand shears.
Be careful with power tools
It’s tempting to put a metal-cutting blade in your saw and rip the metal like plywood. My friend who happens to be a sheet metal worker cautioned me never to do that. The sparks from cutting metal that way can start a fire, and that’s not your goal.
You can do relatively small cuts with a metal cutting blade and power tools. But there usually are safer ways to deal with cutting metal, and some of them are faster.
Guillotine paper cutter
If you’re working with thin brass or aluminum, you can use a guillotine paper cutter. You know, the tool in the corner of the art room that your art teacher in second grade told you to never, ever touch. You can get a cheaply made cutter for under $20 and that’s probably the one you want, as cutting metal will dull the blade. But you’ll save a lot of time. And you’ll probably save a lot more than $20 worth of metal.
To cut, simply raise the blade, line up the metal along the guide, watch your hands, then slice just like you’d cut paper. When making cuts that are several inches long, you will curl the metal slightly, but less than you would using traditional shears, and it’s not hard to straighten the metal back out afterward.
These cheap guillotines aren’t precision tools and you’re using them for something they weren’t really designed for, so in some cases your cuts won’t be perfectly square. You may have to cut the piece slightly oversize and then square it up again afterward. But it’s still quicker and involves less waste than most of the other ways I’ve cut metal in the past.
Electric metal shear
If you want the speed of a power tool, you can get an electric metal shear and get straight cuts without curling your metal. You will sacrifice about a quarter-inch strip of metal with each cut, but that’s less waste than I got with hand tools. You may be able to straighten out and re-use that quarter inch ribbon of metal too, depending on the things you make. The metal on each side of the cut remains straight and clean. And unlike the paper guillotine, an electric metal shear can cut thin steel.
Harbor Freight sells an electric metal shear suitable for 14 gauge metal for about $50. You can find nearly identical tools on Ebay for slightly less. To get a perfectly straight line, you can clamp a straightedge, like the factory cut on the edge of a piece of plywood, to your metal to use as a guide. Offset the straightedge to account for the width of the tool, so the cutting blade lines right up with your line.
A hand-operated nibbler is perhaps the most common tool people use to cut thin metal at home. Like the name suggests, it cuts about a 1/8″x1/4″ nibble at a time. With some practice you can get a rather straight line with one, but I find I have to clamp a straightedge along my metal in order to guide it. Unlike using hand shears, you don’t distort any metal. But like the electric shears I mentioned previously, you do waste a fair bit of metal right along the cut.
I typically use other tools to make long cuts, then use the nibbler for cutting openings. Just draw the pattern you want to cut out, drill a hole large enough to get the nibbler in, clamp on a straightedge if you need it, and punch through. You can also use the nibbler as a finishing tool, making a rough cut with other tools, then using the nibbler to straighten it out.
Be careful with these. Aviation snips tend to leave a mark on the metal that you have to file away. Tin snips look like an overgrown pair of scissors. Tin snips are your cheapest option, but they will curl the metal on one side of the cut, and you may or may not be able to straighten it back out. When cutting, use the back part of the blades, closest to the bolt that holds the part together. That’s where you have the most power. If you try to cut gingerly from the front edge, you won’t have as much strength and you may not get through the metal.
I have a set of aviation snips, but I don’t think I’ve used them since 2005. Tin snips aren’t my preferred method for cutting metal but I still end up using them a lot, especially for those cases where a part almost fits and I need to make a quick cut on the spot.
A professional with a steady hand can cut metal with tin snips and get a nice, clean, straight cut. But I’m not that kind of professional. Then again, sometimes I need a curved cut. When I need something other than a straight cut, the tin snips are my tool of choice. I’ll cut as close to my line as I can, then clean up any excess with a file or a rotary tool.
If you don’t mind a lot of sparks and you have good eye protection, you can cut metal with a rotary tool. I only like it for small cuts though, as I don’t have a very steady hand and I always end up having to clean up the cut afterward. A rotary tool with a cutoff wheel is very quick, but the cleanup work isn’t necessarily fast.
Sometimes I’ll use a rotary tool with a cutoff wheel to make small cuts inside the metal, then straighten out the cut with a nibbler, a file, or combination of other tools. It works nicely for that, because you can make plunge cuts right away without having to start by drilling holes. I’ll also use it when I cut a piece a bit too long. A rotary tool makes short work of grinding a bit off the end so it will fit correctly. When the adjustment is too small for snips, the rotary tool is usually the right choice.
Always, always wear eye protection when using a rotary tool.