Help me choose a plasma cutter
March 29, 2011 4:50 PM   Subscribe

I want to make sculpture with repurposed sheet steel, say 10 to 20 gauge. Probably from old cars, which is on the thin end of that spectrum, but I'd like a little leeway. Tired of waiting for my friend's friend to loan me a plasma cutter, so I'm (gulp) shopping. Do I need the $1400 Powermax 30 or will I be satisfied with the RAMSOND CUT50DY on sale for $500? The guy at the shop I called recommended the $1400 Miller Spectrum 375 X-Treme, which is about when I realized I'm in over my head. What about the $800 Hobart Airforce 500534 250ci, which, unlike the others, includes a built in air compressor? I'm not rich, and this is not for heavy industrial use, but I'd very much like something that works and works well on 120v current. I may well be using this on the sidewalk in front of my apartment, so I'd like it to be relatively portable. Also I'd rather it didn't kill me or anyone else. Merci bien!
posted by jcrcarter to Media & Arts (9 answers total) 4 users marked this as a favorite
I have no first-hand information, but many years ago I was at Burning Man. I'd just built a quadracycle with brazed joints, was thinking about stepping up to welded joints, and was talking with a guy who'd built a solar powered mobile bed about welding for silly vehicles without going all ridiculous on dedicated circuits in the shop, and he said "Miller. Period.". Metalworking that needs welding hasn't come back around again on my "cool things to play around with list", so I haven't yet taken his advice yet, but I've yet to regret buying a tool that was more than I thought I needed at the time. And I've plenty of regrets over buying cheap tools.
posted by straw at 6:03 PM on March 29, 2011 [1 favorite]

I can't tell you what kind of machine to buy, but would like to point out that cutters and welders use a LOT of power. You may be disappointed (if you're lucky) and responsible for an electrical fire (if you're not) if you're planning on running an extension cord out the window from your apartment and cutting on the sidewalk.

You may want to see if you can find a hackerspace or similar that has power, tools and space. You might even be able to barter your way in if you're set on buying a torch: get one that runs on 240V and trade use of the shop/tools for letting other people use your cutter.
posted by spacewrench at 8:05 PM on March 29, 2011

Here's a discussion about inexpensive plasma cutters that may be helpful.
posted by someonesomewhere at 8:06 PM on March 29, 2011

I don't have an answer but I do have some guidelines. There are (at least) three things you need to consider:

(1) Power consumption. Several of the units you link to draw more current (20-30A, at least) than a household outlet can supply. Most of them, if they come with plugs at all, may well come with some funky NEMA plug that won't fit into any outlet you own (for good reason).

(2) Working on the sidewalk implication (a) -- you can't just hang this thing off an extension cord you have lying around the house. Running even 15A through an extension cord means you need a cord rated for that amperage at that length.

(3) Working on the sidewalk implication (b) -- neighbors and bystanders. If you've worked with plasma cutters before you probably already know this, but they're messy as all hell. They create vast amount of nasty, airborne steel dust that's way more annoying even than running a bunch of grinders. It'll foul windshields (and maybe scratch them up when the owner naively uses the windshield wipers to clear the mess), make it hard for people walking by to breathe, etc. That's ignoring the fact that you'll either need to do this behind some kind of welding curtain or station friends at either end of your block offering welding goggles to anyone walking in your direction. (This is under the general philosophy that most safety rules aren't really there to protect you, they're there to make sure the accident report doesn't contain the phrase "innocent bystanders.")
posted by range at 8:12 PM on March 29, 2011 [1 favorite]

One more thing, a 110-volt machine will cut sheet metal without a problem. I don't know if I agree with spacewrench about cutters and welders needing a lot of power, because I've welded 3/16-inch steel with my Miller 140 MIG welder plugged into a 15 amp 110-volt circuit. Although, I've heard about fires getting started because of house wiring faults or extension cords that weren't rated for the current flow.
posted by someonesomewhere at 8:22 PM on March 29, 2011

As mentioned in the first comment, it is very hard to go wrong with Miller. Virtually every seriously good fab shop or individual I know owns Miller electrics for their cutting and fusing needs
posted by bz at 10:08 PM on March 29, 2011

+1 for Miller. I grew up in a welding shop that was in the family for 3 generations (But not an expert at all). I have a nice little Miller 110v wirefeed with a Hypertherm Powermax 350.

With plasma cutting, air is a big consideration. If you want nice clean cuts you want steady, *dry* air. Unsure about the Hobart with an internal compressor. Plasma tends to use a decent amount of air also, but I am unsure of the actual need for your application.

Never heard of Ramsond. Can you get consumables/replacement parts for it? One thing about my Hypertherm, I can walk into any Airgas or Praxair in the nation and get tips and parts for it. All of them will work on it as well.

'A lot of power' depends on tons of factors. Long extension cord? Maxing out the duty cycle? Welding with the voltage all the way up? Anything else on the circuit at the same time? Just some things to consider.
posted by NotSoSimple at 11:08 PM on March 29, 2011

Site manager here. I can't comment on what machine to buy, but the concept of a plasma cutter on the footpath outside your home is quite frankly horrifying. What are you going to do when a bouncy, uncontrolled four year old from the neighbourhood wants to see what you are doing? Think carefully about this, you can end end up with a whole lot more trouble than you want.

Personally, I'd have some pretty serious concerns about using a grinder on the street, let alone a cutter like you are suggesting.
posted by deadwax at 5:40 AM on March 30, 2011

Very thoughtful comments, all. Thank you.

I have access to a secluded/fenced bit of sidewalk so doggies and moppets should be safe.

I have sufficient amperage and will be sure to get an appropriately robust extension cord.

I'm still hoping to ascertain how much I need to spend to get a machine that will cut relatively thin sheet metal such as car roofs, hoods, doors.

Any more expertise out there?
posted by jcrcarter at 8:21 AM on March 31, 2011

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