Straightening metal before welding

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Hi, I am new to this forum. I have worked in the shipbuilding industry for 20 years here in South Mississippi. Right now I am working on a home project which is an aluminum boat that had been hit in the rear and severely caved in the transom. I am trying to straighten the transom with a oxy/acetylene torch and a porta-power. The transom is aluminum channel {6"x2"x 1/8"}. I have managed to get it pretty straight but have wrinkles in the "skin" of the transom. It is all welded, no rivets. I know I can straighten it with heat and water, much like heat shrink. My question is "which side of the metal do I need to heat in order to make the metal pull or push"? I am limited to the area that I can apply heat, the outside is no problem, but the inside has the channel prohibiting where I am able to heat. Do I need to heat and apply water to same side to push, shrink, or heat outside and apply water to inside ?Any help will be greatly appreciated. I need to straighten metal before I re-weld.
Reply:Depends on how thick the aluminum is, if it's 1/4" or less it won't really matter which side you heat, because the heat will flow right through to the other side pretty quick. If it's thick, it probably doesn't have wrinkles. I think you might be better off with a hammer and a dolly.Ian TannerKawasaki KX450 and many other fine tools
Reply:I'd hop on YouTube and find some videos on heat shrinking for autobody. The process is too involved to type out a description, especially without knowing exactly what you're working with. Pictures always help too.
Reply:I'm surprised you can flame-bend thin aluminum, considering that it's so thermally conductive.If it works the same way as with steel, you heat the side you want to shrink, and use water to chill the side you want to stretch.See:https://books.google.com/books?id=UT...ending&f=false
Reply:Thanks, I can only really heat one side. It was hit pretty hard. It is 1/8" thick. There are bulges in the metal, I can only describe them as "hills" and "valleys". I'm trying to understand that if I heat the outside of the transom, of which I have complete access, will cause the metal to move away from heat source ?? I cannot fully heat the inside as there are 6x2x1/8 channels that make up the inside of the boat. I have been successful in partly straightening the inside channels, that I could push with porta-power and heat. I will try to post pictures. I am not sure of my knowledge of how to post pictures though. I am at my wits end trying to straighten things without cutting the channels out to gain access to the inside side of the transoms.
Reply:I will try to post pictures. I am not sure of my knowledge of how to post pictures though.Here is the info you need to post pix of your problem.http://weldingweb.com/vbb/showthread.php...post-a-pictureThat should be more than you need to know on foto posting.
Reply:Thanks Bistineau, I am originally from Shreveport. I grew up fishing on Lake Bistineau until my Dad was transferred from Barksdale Air Base to Keesler in Mississippi when I was 9 years old.
Reply:Originally Posted by DemanNo1Thanks Bistineau, I am originally from Shreveport. I grew up fishing on Lake Bistineau until my Dad was transferred from Barksdale Air Base to Keesler in Mississippi when I was 9 years old.
Reply:aw, no we left there in 1963. I still have aunts, uncles and cousins there in Shreveport.. We fished a lot in Caddo, but I remembered Lake Bistineau. If my memory serves me, we fished around a spillway.
Reply:I tried to take pictures of my transom on boat but it really didn't show the problem very well. I will most likely have to cut out the damaged transom and re-weld. I will be posting to pick some minds on aluminum welding. To Tig or To Mig is the question I ask of Ye ?