How do I really cut sheet metal?

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I have some 18ga steel sheet metal and want to cut a nice 2'x3' section. Perfect cuts with nice 90 degree corners. How can I cut this? I have a plasma cutter but that will not get even close to a nice cut like I want. Any ideas?My $120 Mig - Harbor Freight 151T 220VMy $300 Plasma Cutter - Rattler 40A  110V/220VCurrent project (Miata Trailer):http://www.lightweightmiata.com/trailer/
Reply:Find a shop with a shear.  Pay them to do it.  A couple cuts should be cheap.My name's not Jim....
Reply:Shear would be my #1 choice.#2) You can do decent cuts with a circular saw and a dedicated steel blade, but you will have to back up something that thin to get good cuts. Note the blades are not inexpensive. Use a straight edge as a guide and run the saw tight up against the straight edge. I can get cuts almost as nice as a shear if I'm careful.#3) Plasma. I can make fairly nice straight cuts with my plasma and a straight edge. Note that generally with thin sheet you need the amps turned down and you need to make very fast cuts to get a really nice edge. I often find poor cut quality with the plasma at the tech school is the result of these two issues. The guys want to cut with the machine on max no matter how thick the material is and two they want to take their time. With steel that thin it's almost impossible to out run my plasma even on the lowest setting.#4) Jigsaw, but again you need to back up the material and use a straight edge. If you keep the saw tight and use a fine blade you can get acceptable results many times..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You could trim it to within a 1//4 inch with the Plasma then suing really good shears trim to the exact measurement. I use Midwest brand shears. They make a good hand shear.mooseTimmetalcraft by mooseSoutheast Michiganhttps://www.facebook.com/Metalcraftbymoose  Stupid Hurts!!
Reply:i had always been told plasma was a good nice clean cut ? still kinda new to all of this
Reply:Originally Posted by pbpimpi had always been told plasma was a good nice clean cut ? still kinda new to all of this
Reply:failing that, clamp a straight edge where you want the cut to be and use a thin cutting disk in a grinder, remember to allow for the thickness of the disc when clamping the straight edge, and just run the grinder up and down until its through.I've cut up a large 8' x 4' sheet of steel this way before
Reply:Before acquiring a plasma torch I used a pneumatic nibbler which works pretty well up to 16ga steel.  No discoloration or distortion from heat.  Guide it along a straightedge clamped to the sheet and allow for the "kerf".  You can pick up a cheapo at HF.  .- MondoMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:I went the diablo steel blade in the circular saw route to cut practice coupons out of 16ga salvage. I let the cut line just overhang the edge of the table for support.Works great. Clamp up a guide fence, allow for the kerf, and have at it.If you already have the plasma (insert drool icon here), I would think with a guide and the machine settings as described above, its worth some experimentation and practice time since you already have a very capable cutting method.Lincoln AC/DC 225/125 and WP17. 75A AC is for pipe thawing!HH 140 - new addtion 9/2012.I didn't agree, but hoped for Hope and Change.I got change for myself and my family: for the worse.This is the reality of: Barackalypse Now. Again.
Reply:I have used the steel demons with great results. Has anyone ever used the lenox steel blades they have at lowes?
Reply:is the best tool for 18 ga on down.
Reply:All these suggestions are good,  I like a circular saw,  have the HF nibbler too and it works well.  for Plasma it also depends on if you have a drag cut plasma or if you have one that requires a stand off.  a drag cut tip on a HT or ESAB will give very accurate cuts of sheet if you use a straight edge of some kind.  the tip will go right up against both the material you are cutting and the straight edge.   you will need to practice to get the right amp and travel speed settings.   too slow a cut will give you more dross.  turn down your amps till you find a travel speed that works well for you.Your $300 plasma may be the reason you cannot get nice Plasma cuts..Last edited by soutthpaw; 12-09-2012 at 09:55 AM.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Originally Posted by Scott Youngis the best tool for 18 ga on down.
Reply:Hands down, plasma cutter with a straight edge. Better then a shear, in my opinion, because the shear leaves a sharp edge. Any method will require a quick clean up with  flap wheel.Tim Beeker.
Reply:As stated, I tried my plasma but not with good results. The cuts I get with it are good for "art" but not nice enough to get a good square plate. I'll have to do some experimentation. I have a HF pneumatic nibbler (very messy - not great cuts) and bought a HF pneumatic sheer but it is still in the box. I'll see how it works.FWIW, the reason I am asking is that I just built (well, in the process of - still a couple of hours away) a sheet metal brake. I'll show you guys some pics when I get it finished.My $120 Mig - Harbor Freight 151T 220VMy $300 Plasma Cutter - Rattler 40A  110V/220VCurrent project (Miata Trailer):http://www.lightweightmiata.com/trailer/
Reply:Popcorn is cooking....Miller diversion 165Miller mig 211Hypertherm pm 30Milwaukee 6230 14 inch chop sawMd 45 mag drill (RIP; fell on its head)New MD 45! Thanks to the esposa!Finally got an O/A setup
Reply:I bought a HF metal cutting saw on sale . Can't believe it is still cutting and running. I paid $60.00. With a straight edge its great.
Reply:I have used every method mentioned here with high degrees of success. The key to most of them is to use a guide bar. I just cut up a 4x8 sheet for a customer in 16 gauge in the following manner. I ordered the sheet wit 5 of the know dimensions sheared. I had to cut some of the 4' sheared strips in half. I used the Milwaukee for the ones that I could afford the kerf loss on. The others I used a zip wheel. To use the zip wheel I generally use a carbide scride and scribe a line for the finished piece, use the zip wheel and get it close, use a sanding disk to get it even closer, then use a heavy single cut file to true it perfect if it has to be.
Reply:If you're not getting a clean cut with the plasma, you're doing it wrong.  You should be able to get a nice clean cut.  For thin stuff, you need to move way faster than you think you do.  And turn down the power.  Basically, what DSW said. Shear would be my first choice as well...but I don't have one...
Reply:You can do a great job with a plasma, a guide, and the right travel speed.  Any areas that are a little rough, run over them with a flap wheel on a grinder real quick.
Reply:Keep it simple.  Circular saw and a metal-cutting blade.  [ame=http://www.amazon.com/D0748F-Diablo-Ferrous-Knockout-PermaShield/dp/B00008WQ3B]The blade is $35 from Amazon[/ame] and will last a long time.  With a straight edge, you'll get a very nice cut.  No clean up necessary, unless you want to dull the edge down to avoid cutting a finger.I used one to cut this cabinet:Down to this:In order to make this:In fact, everything you see in that sink area, including the countertop part, was made by cutting up that one Strong Hold cabinet.  The only cut I didn't use the circular saw for was the curved cut on the countertop face.  I used a jigsaw for that.Jack OlsenMy garage website
Reply:Anyone ever used one of these...drill attachment??Last edited by shortfuse; 12-10-2012 at 01:33 PM.
Reply:If you have bandsaw, you may want to use it. Just change a blade designed for metal.
Reply:I use plasma for virtually all sheetmetal cutting. Hand cutting is normally done with a guide or template.....if you have a major brand (like Hypertherm) there are consumables designed specifically for thin materials...these cut at lower power with a finer kerf, and keep speeds manageable. On a cnc plasma....same thing.....small nozzle orifice and low power, accurate cut height and the right speed....cuts are clean and dross free, and extremely accurate. And did I mention fast?I agree that using plasma at the incorrect power level....or with a nozzle that is designed for high amperage....is definitely not going to produce a nice cut.Jim Colt
Reply:I bought a $20 carbide blade from HF to cut sheet metal with.  I've used it on 16 ga to 1/4" plate.  I use a cheapo Skill saw, it's slower than a better saw and works good for this.  When the saw dies, I'm going to get an evolution 7 1/4".With a guide, it makes great cuts.  Without a guide, I can't keep it straight at all.Thermal Arc 211i FabricatorAutoArc 130Lincoln AC 225O/A setAssorted hand tools and implements of destructionThe other thing to consider is the shape of the parts that need to be cut. If everything is straight and square...then saws and shears work fine. Here are some sheet metal parts cut with plasma:1st is .080" aluminum2nd is 26 ga galvanized (these are the scrap pieces, cut at 350 inches per minute)3rd is from 12 ga steel...holes are as cut with the plasma, not drilled. They are 3/32" dia.Last is a sign made from 14 ga.....cut at 225 ipm.You really cannot cut contoured parts like thes with a saw!Jim Attached ImagesLast edited by jimcolt; 12-12-2012 at 11:36 AM.
Reply:Jim last pict you posted of the "buckles", CNC or handheld? I don't see the clean precision I'd expect at the radius in the slots I see on the left hand side pieces if they were CNC cut. Hand held and template perhaps?.No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I pulled that pic out....that was a job that the user required cheap and fast.....with loose tolerances. So that is what they were! They could have been much better if the lower amperage process was used.Jim Originally Posted by DSWJim last pict you posted of the "buckles", CNC or handheld? I don't see the clean precision I'd expect at the radius in the slots I see on the left hand side pieces if they were CNC cut. Hand held and template perhaps?
Reply:Originally Posted by rmcelweeFWIW, the reason I am asking is that I just built (well, in the process of - still a couple of hours away) a sheet metal brake. I'll show you guys some pics when I get it finished.
Reply:Originally Posted by Jack OlsenI used one to cut this cabinet: