Plasma cutter or torch???

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I'm planning on doing quite a bit of work on my trucks... On my existing welding truck, I want to get rid of the under bed boxes that are on it (that leak so much that they're pretty much un-usable), skirt the bed and build my own boxes into the bed.  As soon as I get my '99 dually out of the body shop, I'm going to build a custom bed for it, rigging it up as a pipeline rig.  I'm just going to start from scratch on it, building it from the frame up.Here is my issue... I don't have much experience cutting thinner material.  Welding it is not a problem, I've welded exhaust pipe with 3/32" 6010 before I had a mig, and now I have a 140 amp and a 300 amp mig both, so that's not an issue.  But I havn't cut much plate thinner than 1/4".  For these projects, I see using from about 11 gauge to 1/8" and 3/16" plate.  What is the key to getting a good, clean cut on thin plate with a minimum amount of warping with a torch?  Will fast travel speed with a really small tip work?  If so, what size tip for a Victor torch?  I have a small Victor torch, but really prefer the bigger torch.  Just more comfortable in my hands.  Also, a tip for the larger torch would fit my barrel torches, if I was to come up with some sort of track to run one on.I'd love to have a plasma cutter for this project, although I've never used one.  I just hate to put out the money to buy one, that might not get used again for no telling how long...Any and all ideas will be much appreciated...Randy
Reply:If I had a lot of thin stuff to cut for a project like this, I'd probably look at having most of it sheared before I bought it, or dropping the money on a dedicated steel circular saw and blades. I'm betting 95%+ of the project could be done with straight cuts. You might even look at simply having some of it CNC laser or plasma cut as well for the irregular shapes of the side pieces possibly. With CNC the cut speeds are faster meaning they get less heat in the material and usually a higher level of precision than you can get by hand..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've read about some of the steel circular saws on here, and didn't even think about that option.  What thickness are those saws worthwhile up to in reality?  I can hand cut with a torch pretty straight, and even better if I set up an angle iron guide or something, but really think warping would be a major issue with this thin of metal.  I cut up some old red iron z purling a while back, to box in a rolling tailboard to mount my lights in, and I don't know the thickness of it, and that stuff warped like crazy.  It was small pieces, so it wasn't that much of an issue to get it straightened out and welded on, but it was stuff that was left over from when we built the shop in 1988.  This material for the most part will be new material that I'm buying, and I don't want to risk messing it up...I will check into having what I can sheared.  I'd also like to get some of the corners for the boxes broke (I think that's the right term).  This kind of fabrication is kind of new to me.  I'm not used to working with this thin of material.  The way I've drawn the bed up, the biggest irregular shapes are going to be the wheelwells.  Most everything else will be pretty much straight cuts.  I'm not going for "fancy", more functional.  The bed is going to be 8' by 9', with the corners cut off at a 45 degree angle.  My truck is 8'2" outside the duals, so the bed will have a pipe "rail" around the bottom, with the pipe following the wheelwells to serve as fender flares also if that makes sense.  I like the looks of the narrower beds, but i need the extra space.  Especially all the lockable storage I can get.  I'd put an 11' bed on it like on my '96 if I had enough wheelbase.
Reply:My qualifications:  Part-time amature, uncertified weekend warrior.  But I have been around for a while and didn't ride in on a turnip wagon.I have cut steel sheet and thin plate with: O/A torch, O/Prop torch, pneumatic nipper, gargantuan hydraulic shear (in welding class), plasma.For any metal thicker than 16 gauge a shear is an extraordinarily expensive investment.Pneumatic nipper is limited to 16ga or thinner and doesn't really leave as nice an edge as one might think. A steel cutting circular saw will make a nice straight cut, won't go around curves.Any oxy-fuel gas torch heats too wide a swath and lends to unwanted distortion.A small hand-held plasma torch makes really nice cuts, straight line with iron bar as a guide, and can follow any curve or contour you can draw on the metal with a scribe, crayon, or sharpie marker.  My Hypertherm Powermax 30 is one of the best investments I have made in tools.  It cuts a 1/16" kerf quickly through anything up to 1/4" with near zero distortion.  It can cut through 3/8 a little slower, but still makes a nice cut.  It can be powered by standard 15A 115V circuit for thin sheet, but requires 220V/20A for anything over 3/16.  It does require an external source of comnpressed air (5CFM @ 90 psi) or can be connected up with bottled nitrogen if necessary.Plasma is the most versatile metal cutting tool invented.  And it isn't limited to iron, steel and ferric alloys.  Plasma will cut any metal that conducts electricity.  How profound is that?There are small plasma machines today that have their own built-in air compressor, all they need is electricity. Hobart has an "airforce" model that retails on-line for less than 800 bucks.I think that once you start using a plasma machine you wonder how you got along without it all those years.  Plasma ia super cool!    - 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 agree a Plasma is so much easier than a gas bottle and torch, Not only will it be easier to use but you have more control than using a larger torch setup.As the Plasma reaches a high temperature almost instantly it will restrict the heat more closely and you don't have to preheat before cutting like you do with a torch which heats up a larger area with a risk of distortion.
Reply:This is a area the Plasma will be very good in , and it will cut as you know any shape/profile you desire. Also a plus is the feature being able to wash of welds with very good accuracy. If you need a recommendation - i run a Hypertherm 45 and it has been a great machine, consumable life is extremely long and with the drag tip its a breeze on this type of work. If you have a item to replicate a few times, a pattern can be made and it allows you to cut as many as needed, just dont forget to shrink the templete to account for the offset of the nozzle.  As far as a metal skil saw - i run a 9" Evolution and do routine cutting on 3/8" and thinner metal with it. On straight cuts clamp a straight edge and you have a perfect cut. These are a very economical tool that cover a lot of uses.
Reply:I built my boxes very similar to what your trying to accomplish. I tried one cut with the metal skil saw blade and decided it was way too slow. I cut all the rest with my plasma, much faster and easier.I woulld also have the doors braked and bent, makes them stronger and easier to waterproof..
Reply:Plasma cutters works as a electrics spark currents will be passing through in the shop air systems in heavy vehicles. It hight speed passing molten metals are direct in the venturi carburators systems.
Reply:Originally Posted by pakwaeannaPlasma cutters works as a electrics spark currents will be passing through in the shop air systems in heavy vehicles. It hight speed passing molten metals are direct in the venturi carburators systems.
Reply:You could use a narrow kerf single-jet cutting tip on an O/A torch...  minimal heat input and super clean cuts.You didn't build that.'85 Miller AEAD-200LE
Reply:i actually just got done cutting 16ga on my cnc plasma, and there is no distortion to it. i was cutting at 150 inches a min. you could cut out all the needed parts for your truck in about 2 hours, and everything would be straight and ready to assemble. you could save some hassle (ie cost to you) for the cutter and do the layout for all your parts, via inkscape (free to download) and save the files in the required format they need for cutting. then you supply the steel, and it could probably be done for a few hundred. and you would just have to glue all the flat pieces into the shape of the bed. the other alternitive is buying a hand held plasma cutter, and going after it. find a used 40 amp machine on CL and you could probably use it for the project and then toss it back up on CL for what you paid for it. and would be able to "rent" it for free. just some thoughts.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:If I was doing this as a one time job, I would take an old yard sale regular circular saw and get the abrasive blades for they make for it. Its not too slow, I use these to cut boiler stacks down  regularly. The blades can also be fit onto a grinder (7 works better than 4.5, but Ive used both), to cut small pieces or get into tight spots. This is NOT OSHA approved, the blades will occasionally fly appart, be wearing leathers, gloves, and face shield if you mount these on a grinder.