General welding questions that dont fit in TIG, MIG, Stick, or Certification etc.
Fishbum
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    Fri Aug 08, 2014 12:04 pm

Looking for help on how to weld a large sheet
60"x96" of 1/8 or 3/16 to another sheet on the 60"
Side butt joint with out it warping all over the place
Talking about a boat bottom! Thanks
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Friction-stir is probably the best option for sheets that size, but would have to be farmed out. That's not home-shop equipment.

MIG in short bursts, stiches scattered along the joint, with a rapid quench each time (perhaps compressed air) to help limit heat input and the spread of heat will reduce, but not eliminate, warpage. Planishing will help restore the metal, if you can set up a power hammer or English wheel to handle the 60" joint.

I expect more answers, possibly more practical, will follow.

Steve S
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TamJeff
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I have had to TIG weld rather large butts in 11 gauge and on aluminum veneer. The only way we could manage it with next to no distortion was to sandwich it between tiles made of 1/2" steel plate on a flat table. I had two sections of plate that were about 12" x 36" and the rest were 16"x16" with the joints in the plates staggered. It was essentially like welding the sheets in a press, with just enough room for the torch.

Welded in place on a hull, there really is no way to avoid it completely, and ends up just being an expected byproduct of the process. Some boats designed for aluminum, will have the hull designed/framed so that the lay of the panels has it stressed or captured in such a way in which to minimize it, and the joints strategically placed as well, regardless of whether it always makes most efficient use of the sheets.
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TamJeff, you have some ingenius solutions,always a helpful read.
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TamJeff
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rick9345 wrote:TamJeff, you have some ingenius solutions,always a helpful read.
We had tried a lot of different ways. We just happened to have enough plate around to make it an effective (albeit heavy) solution. When they closed that shop, I tried to get those plates but they had already sold the contents of the building to a scrap dealer who would not part with them, even for a fair price. It seemed as if he was reluctant just because he could tell I wanted them. Some of them had series of holes drilled and tapped in them for holding specific parts that had taken a bit of time and work to establish accurately and the plates had a nice oxide patina on them and were dead flat.
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Fishbum
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    Fri Aug 08, 2014 12:04 pm

Thanks guys, guess I will try to get full length sheet
And not have to do this but joint. But will still have 16' joints where sides meet the bottom
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