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Bending Corners in 1/4" Steel Plate

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  • Bending Corners in 1/4" Steel Plate

    I plan to start building my own custom outdoor wood boiler (gasifier) in the next couple of weeks. The firebox and secondary combustion chamber will be about 2' x 3' x 5' tall. You can get somewhat of a picture in your mind if you think of a downsized refrigerator. For the sides, I would like to take a piece of 1/4" plate steel that is 10' long, bend 3 90 degree corners and then weld the 4th where the ends of the plate come together. This compartment will all be encapsulated by water which is 1 of the reasons I only wanted to have 1 welded side seam other than top and bottom. I am trying to figure out a way of bending these corners and keeping it square as they will each be 5' long and it is 1/4" steel.

    I had thought of marking my corners out with a square and drawing a chalk line from top to bottom of each. After that, I had thought about using a cutoff disk on a grinder and make a tapered slot down this chalk line about 1/8" deep to "relieve" the metal and allow it to bend. After completing the bend, I could just weld back up the bend to strengthen it back together.

    Since I am a novice, I would like to get suggestions from the more experienced guys around here. My equipment is limited to a HH187, plasma cutter, angle grinder, die grinder, and 20 ton press. I don't have anything more extensive than this so I need to make the best with what I have.

    TIA.

  • #2
    BB.
    Take your plate to a fab shop that would have a big enough brake to bend that 1/4" plate the way you want it. That I think would be best way to go.
    sigpic

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    • #3
      I concur. You don't have the machinery to make a break in 1/4" thick anything. That length will require at least a 100 ton brake.

      Most large fab shops have the equipment. If there is a Contractors Steel Service Center near you, they will as well.
      So little time...So many machine tools.........
      www.flipmeisters.com

      Miller, Hobart & Lincoln TIG/MIG/-
      Hypertherm Plasma (Thanks Jim)
      Plasma-Cam DHC (coming shortly)
      Harris OA
      Too many motorcycles.............-
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      • #4
        I'd be looking for a couple large, used propane tanks that would nest one inside the other.
        --- RJL ----------------------------------------------

        Ordinarily I'm insane, but I have lucid moments when I'm merely stupid.
        -------------------------

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        • #5
          Originally posted by usmcpop View Post
          I'd be looking for a couple large, used propane tanks that would nest one inside the other.
          I know what you are getting at, but this isn't the same kind of outdoor wood boiler. This is a gasification boiler. It is about 3 times as efficient as a standard old smoky owb. The inside is lined with 2-3" of refractory cement to insulate the heat from the walls, thus causing a higher (600-800*) burn temp. The smoke is then drawn back thru the coals and is introduced to hot, fresh air. This causes the smoke/exhaust to all burn all over again at around 2000-2300*. The refractory cement is what insulates the steel to keep it from melting. The high temp exhaust air is then routed out thru a heat exchanger that is surrounded by water.

          Some states have now outlawed the old outdoor wood boiler due to the exhaust. The gasser only uses about half of the wood and within 5 minutes of the inducer fan coming on to supply air to fire and secondary combustion, the exhaust coming out is clear.

          Here is a video that will explain it a little better. http://www.youtube.com/watch?v=R6Ii7u1Ku8c

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          • #6
            Hey boatboy,
            I have bent 1/4" plate with ease by doing what you were contemplating for many years since I don't have a huge brake or large shop. Mark your bends, use a cutoff wheel & get to a depth where it will bend easily.... .100 deep should suffice. Here's some pics of bends I made with 1/4" & 3/16". If it is going to be subject to water, better make sure you have perfect weld fillet. It's not hard.....

            Denny
            Complete weld/mach./fab shop
            Mobile unit

            "A man's word is his honor...without honor, there is nothing."

            "Words are like bullets.... once they leave your muzzle, you cannot get them back."

            "I have no hesitation to kill nor reservation to die for the American Flag & the US Constitution."

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            • #7
              Being in the steel trades for the last 30 years or so, the only caution I will add is....

              Whatever the material is, you better make very certain it's low carbon HR sheet and the Rockwell is low as well. If the material has a high Rockwell and you score and bent it, it will fracture off.

              That's how steel is slit on a slitter to make slit coils. It's continuous fracture at a pre-determined depth, knowing the Rockwell and the chems.

              Most small lot material will have questionable chems and the Rockwell won't be obtainable from the supplier.
              So little time...So many machine tools.........
              www.flipmeisters.com

              Miller, Hobart & Lincoln TIG/MIG/-
              Hypertherm Plasma (Thanks Jim)
              Plasma-Cam DHC (coming shortly)
              Harris OA
              Too many motorcycles.............-
              sigpic

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              • #8
                Yorkipap,

                That is some very good advice. I have used this method in the past when it is a relatively small project, and I want or need a tighter radius. Sometimes it is easier this way than when using the brake because of allowing for springback. Ok when you get the correct radi, but go too far and it is a pain sometimes.

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                • #9
                  Originally posted by boatboy63 View Post
                  I am trying to figure out a way of bending these corners and keeping it square as they will each be 5' long and it is 1/4" steel.


                  Since I am a novice, I would like to get suggestions from the more experienced guys around here. My equipment is limited to a HH187

                  TIA.
                  Just my thought and you can take it for what its worth. I built wood/coal burners for about 10 years. You need a bigger mig or a stick machine to weld 1/4" and to do any length as in a boiler. Trust me on that one...Bob
                  Bob Wright, Grandson of Tee Nee Boat Trailer Founder
                  Metal Master Fab
                  Salem, Ohio
                  Birthplace of the Silver & Deming Drill
                  http://www.ceilingtrains.com/
                  http://groups.yahoo.com/group/sawking/
                  http://groups.yahoo.com/group/southbend10k/

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                  • #10
                    Used "tombstone" Lincoln AC225s are common for about 75 bucks on Craigslist and trader papers. A machine that will do DC gives more rod choice, but that would git 'er done.

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                    • #11
                      What about heating it?

                      I make bends in 3/8 steel all the time. I just heat up the area to be bent with a a/o rosebud and put it in my 20 ton press and just bend it!

                      Heat makes all the difference and makes it really easy.

                      Why cut into the steel, bend it and then weld it when this is way easier and a better bend. If I am doing a 90 degree or greater bend, then I do score the inside of the bend due to the metal crinkling in the inside of the bend. But for any bends less than say 75 degrees, I just heat it and bend it.
                      Cobra 2000 A/O torch ( all USA made)
                      Everlast Powertig 250EX (US company, Chinese MFG)
                      Everlast Powerplasma 50 (US company, Chinese MFG)
                      Hobart Handler 210 (US company, Chinese parts)
                      GoWeld portable mig (US company, Chinese parts)
                      Evolution rage 2 cold saw (USA company, USA parts)
                      various other metal working tools

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                      • #12
                        What about heating it?

                        Never mind......I did not see that the bends were 3 to 10 feet in length.
                        Go to a metal fab shop. Much easier.
                        Cobra 2000 A/O torch ( all USA made)
                        Everlast Powertig 250EX (US company, Chinese MFG)
                        Everlast Powerplasma 50 (US company, Chinese MFG)
                        Hobart Handler 210 (US company, Chinese parts)
                        GoWeld portable mig (US company, Chinese parts)
                        Evolution rage 2 cold saw (USA company, USA parts)
                        various other metal working tools

                        Comment

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