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welding warped my sheet,,,how to straighten

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  • welding warped my sheet,,,how to straighten

    I knew there was a good chance this would happen. I miged a plug into the I/O hole on the back of an aluminum boat. I had nightmare welding issues...mostly because of the swirling winds..and my gas setting was only about 22 . plus it took me a while to get a feel for the process. the verticle surface of the boats transom did not weld anything like my test pieces on the horizontal bench!! the result was i welded a lot longer than i should have... and i ground away a lot of my poor welds, and now the transom sheet aluminum has a serious bow in it. I know there is an art to straightening sheet metal with heat....doesnt anyone have some tips or a GOOD source to read up on it??

    thanks

    bob

  • #2
    If you mangled it trying to weld it, I might suggest letting a professional straighten it for you.

    Comment


    • #3
      Get on the opposite side of the bow and with a plunger see if you can pull it back.

      Comment


      • #4
        Originally posted by jrscgsr View Post
        If you mangled it trying to weld it, I might suggest letting a professional straighten it for you.
        who would be a professional at something like that? a professional welding house?

        the results dont have to be perfect. the top of the sheet( the transom) is like a lazy S. Its like the top stretched, but since it is captured on the ends it is bowing in the middle. Normally Id prefer to do as much myself as possible..sure there are specific things you need to hire someone.. this boat project is going to be a utility hunting boat. as such id like to try it myself.. i should have let it cool more and staggered my wedling...but with the issues i was having, and wanting to correct it..i kept at it. certainly a mistake. It is wedled fine now. I finally got the mig to puddle and flow for great penetration . I think the wind was killing me the most.

        bob

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        • #5
          welding warped my sheet,,,how to straighten

          who would be a professional at something like that? a professional welding house?




          This guy.

          Comment


          • #6
            Body man

            This is probably more of a body man problem, hammer and dolly work. The transom is probably thicker than most body panels, but since it is aluminum, you should be able to use the same basic technique. He did not say how thick it was.

            The body men think in terms of using a hammer and dolly to stretch the weld area to compensate for the shrinkage from the weld. They would also be pushing the panel back into line, but you will never get it back in line if you do not correct for the weld shrinkage.

            A photo would be helpful.

            A real body man, especially somebody who knows how to make a panel from scratch, could probably look at it and tell where to hit it. Somebody who does not do that work might make it worse instead of better.

            I am not as good as a good body man, but I do a fair amount of hammer and dolly work, and could figure out where to hit it.

            My two cents.

            Richard

            Comment


            • #7
              yeah I am thinking this wrappage isn't a body man job.....its not like a dent...it is a large area wave.... I am almost thinking to slice it down the middle and then weld it back a little at a time so I don't re warp it..




              its all a learning curve, I think most guys who are experts have to realize, that because its second nature to you, it isn't to everyone else. I got through that myself as a toolmaker, explaining "simple" stuff to people who are trying to learn. The trick is offering an answer that leads to the person do it right...even if its EVENTUALLY

              thanks

              bob

              Comment


              • #8
                Can you show a pic of the welded area? Not a close up but just a general view to see where the actual welding was done. From the pic you have here it looks like more is going on than just normal shrinkage of that plate. Almost like the sides have pulled in some which could be due to the location of the welding.

                Comment


                • #9
                  I think if you slice it & weld it together it will pull the sides in even more.

                  Comment


                  • #10
                    if the transom is wider at the top than the bottom maybe what happened is the bottom cooled and shrunk pulling the sides in at the bottom ... causing extra metal at the top to buckle. If you spread the sides at the top maybe you will pull the bow out.


                    That or cut the transom, pull the sides together, overlapping them, mark the extra metal that needs to be cut out and reweld with 2X4 set across the top to prevent the sides from pulling in as the weld cools.
                    Last edited by tackit; 05-06-2013, 10:01 AM.

                    Comment


                    • #11
                      welding warped my sheet,,,how to straighten

                      Yep. MMW your dead on. Don't cut & weld, just make it worse.
                      I started welding in the 70's, was a body man painter many years. Also a Blacksmith, farrier (did that full time almost 10-years) still do part time but hv my own welding fab shop now. Like most guys I still warp things, so don't feel bad.
                      But all things considered one of the hardest things for me to learn & understand is straightening, ie using heat which is the best way if u can master it. Really it's the art of shrinkage, or contraction which is what bit u in the 1st place. I don't hv time to explain now and don't hv link with me which explains. But if u do a search you'll find it. Read read read then try it. Takes a lot of trial & error (I still struggle with it) but all things considered its the best way to straighten metal. There are Co's that straighten massive beams as under bridges etc. using heat.
                      It's truly a art worth mastering ie a lost art in this generation. The old timers were masters but most of them are gone. :-(
                      Greg

                      Comment


                      • #12

                        that was while I was fitting the plug.





                        the last of the welding...


                        then lastly the panels view....I can measure thw width of the top of the transom..i had measured that before trying to calculate the size and shape of my outboard bracket...so I have that # to compare what it is now... that will tell me if the gunnels came inward...if not, then the metal expanded and it is bowing because the sides are fixed.



                        that measure will say a lot about what happened.
                        frankly I am thinking if the sides pulled in, it will be an easier fix.... I cant imagine I imparted that much heat that it reached the sides of the hull!!! I think the grinder created as much heat or more for a broad area, than the welding...

                        bob

                        Comment


                        • #13
                          It's not that the heat reached the sides & they shrunk. It's that the lower part of the back plate shrunk therefor pulling in the sides which caused the top of the back plate to wrinkle because it did not shrink like the lower part. Just my guess. When you measure across the top you will know.

                          If it did pull in then cut a brace or jack it open to push the sides apart to where they should be. Then weld on the other plates that you have laid out in marker. This should take care of most of it. Maybe even make the brace slightly big.

                          When you weld, after it cools there is always some shrinkage, never expansion.

                          Comment


                          • #14
                            The heat wouldn't have to reach the sides of the hull to pull the sides in, all it would have to do is pull from the weld making there be to much metal at the top causing it to buckle. The metal has to do something if there is to much of it. I don't think the bow is a heat warp, I think it's a buckle caused by to much metal at the top caused when the bottom portion of the transom shrunk after the weld cooled.

                            I don't see why it couldn't be cut and welded, they repair aluminum boats all the time.

                            I would appreciate someone explaining to me in laymen terms why welding wouldn't work, albeit the weld is at a stress point if an outboard motor is going to replace the outdrive. Thanks for any insight on this, I'm always looking to learn from the pros here.

                            Comment


                            • #15
                              Originally posted by tackit View Post
                              The heat wouldn't have to reach the sides of the hull to pull the sides in, all it would have to do is pull from the weld making there be to much metal at the top causing it to buckle. The metal has to do something if there is to much of it. I don't think the bow is a heat warp, I think it's a buckle caused by to much metal at the top caused when the bottom portion of the transom shrunk after the weld cooled.

                              I don't see why it couldn't be cut and welded, they repair aluminum boats all the time.

                              I would appreciate someone explaining to me in laymen terms why welding wouldn't work, albeit the weld is at a stress point if an outboard motor is going to replace the outdrive. Thanks for any insight on this, I'm always looking to learn from the pros here.
                              there is no structural support needed on that sheet. bracing inside and an outboard bracket will be BOLTED to the outside, making a sandwich of that sheet.. bracing inside will go the floor ribs as well as side angle bracing to fasten the transom sheet to the sides of the boat... the sheet on the transom just need to hold back water, and go along for the ride mostly. The motor will be mounted to the bracket about 27" away from the sheet that bent.

                              bob

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