Less frustrating way to cut sheet metal?
February 22, 2014 9:21 PM   Subscribe

What's the easiest way to cleanly cut a small-ish piece out of a sheet of aluminum?

I'm repurposing an old computer case and need to make a new plate for the back to hold the I/O shield/port cover for the new motherboard. The piece itself needs to be 3"x9", with a smaller rectangular hole cut out of this piece. I picked up a few sheets of thin aluminum from Home Depot and was able to cut them up using a Dremel but the cuts weren't very clean or even. It turns out that I need thicker and sturdier material, so before I fire up the Dremel again and spend more time cleaning up the edges than I did actually cutting, I figured I'd ask if there was a better way. I considered shears but figured they'd warp the metal too much along the cut edges and I don't trust that I'd be able to create any straighter of an edge with those anyway.
posted by Venadium to Sports, Hobbies, & Recreation (12 answers total)
HugBuddy says "you need an angle grinder 4" cut off wheel - the thin cutting disc". He says if you don't want to buy an angle grinder, take your metal to a steel fabricator and they can do it in minutes. If you are in a city, there is probably one nearby.
posted by Kerasia at 9:31 PM on February 22, 2014

If you don't mind a little hand cramping, there's always the nibbler.
posted by Mister Moofoo at 9:35 PM on February 22, 2014

You can rent tools such as angle grinders.
posted by aubilenon at 9:46 PM on February 22, 2014

Find a sheet metal shop around you and ask them about it. I bet if you find a smaller one that has a sheet metal brake you can get exact and precise cuts for $5 and 30 seconds of time.
posted by sanka at 10:39 PM on February 22, 2014 [1 favorite]

An angle grinder will work and fast, too. They are pretty inexpensive - you can find a cheap one for 30 bucks.

They aren't terribly precise, however.

My go to for this sort of thing is a hacksaw, or a bandsaw. You can get better precision that way. A hacksaw is cheap - maybe 10 bucks, but it is a hand tool. A bandsaw is pretty pricey, but worth the investment if you are going to be doing this sort of thing often.
posted by Pogo_Fuzzybutt at 12:15 AM on February 23, 2014

I think an angle grinder seems overkill for something like this. What gauge (i.e. how thick) is the aluminum you want to cut? Do you have other tools like a hacksaw, a vise or clamps, a file? A bandsaw or even a table saw can work if you have access to a shop.

With small handheld tools like Dremel rotary tools, hacksaws, etc., you probably will need to spend some time cleaning up the edges afterwards. But that cleanup work doesn't have to be difficult or painfully slow, which is why I ask about files and vises. A sharp single-cut file will cut aluminum very well if you have something to hold the workpiece still for you.
posted by jon1270 at 4:24 AM on February 23, 2014

If this were a problem in my house, and if the gauge of the metal wasn't too terribly thick, I'd use a jeweler's saw with a tightly threaded blade. I've sawed celtic knot shapes out of 16ga sheet silver that required minimal finishing with saws like these.
posted by ersatzkat at 5:17 AM on February 23, 2014

It is possible to cut sheet aluminum with a table saw, using a carbide blade. Ideally you would use a zero-clearance insert and a negative-rake blade, but I've done it (with 1/16" to 1/8" aluminum, which is pretty stiff) with my regular set-up.
posted by mr vino at 7:15 AM on February 23, 2014

I've done lots of stuff like this with a water jet. If there's a place nearby that has one, it will be precise and leave a clean edge.
posted by spikeleemajortomdickandharryconnickjrmints at 7:34 AM on February 23, 2014

Why not just use shears and gently flatten anything that's warped out with a ball-peen hammer? It sounds like it would be the quickest, simplest way.

Or - get it done with a waterjet or a plasma cutter. Super clean, but lots of setup time.
posted by suedehead at 11:47 AM on February 23, 2014

I did manage to do a much better job using center snips (still needs to be flattened out a little but at least the edges are straight) but the section that I need to cut out of the center is still going to be tricky.
posted by Venadium at 7:37 PM on February 23, 2014

For the section in the center, consider a jigsaw with appropriate blade marked for cutting aluminum. Mark the shapes you want to cut, and then drill a hole in the inside section. Then the blade of the jigsaw can be drop down through the material. Hang the section you are cutting just off the edge of your workbench, and keep an eye on where your blade is in relation to the workbench. I recommend clamping the material down too.

Jigsaws have variable speeds, and you should match the speed to the blade recommendations. You can also practice on a piece of scrap and find what speed works best. Cutting will be easy and smooth when you find the appropriate speed. Let the blade do the work, and don't try to force it through the material.
posted by ohjonboy at 7:48 AM on February 24, 2014

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