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Welding aluminum without overheating paint

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  • Welding aluminum without overheating paint

    I got an interesting challenge ahead of me today.

    I was asked if it was possible to weld onto the backside of piece of 1/4" aluminum without overheating or damaging the paint on the front side. Its a very artistic piece on the front but it was not mentioned until after the piece got painted, that there should be a handle on it so now I am trying to see if its possible to weld the back side without ruining the front side's paint job.

    I was thinking that sitting the piece up so front and back are visisble and then putting a fan to cool the front as much as possible and then just welding the back side.

    Anybody ever done anything like this? Any ideas are appreciated, going to be doing it today.
    if there's a welder, there's a way

  • #2
    Not possible. Wishful thinking.
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    • #3
      See what you do is, calculate the time-dependent heat gradient distribution by way of the 3-D heat flow partial differential equation, using welding voltage and amperage to dictate Joule input. Set the boundary conditions to approximate the plate in the immediate vicinity, including the thickness. Find the maximum temperature using aluminum's heat conductivity once you arrive at a peak heat energy transfer to the area in question. Here are the equations:


      2- and 3-Dimensional heat flow







      Man, I loved doing this stuff in college. Pages upon pages of calculations.
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      • #4
        42. That's the answer to your equation.

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        • #5
          Wow. Well, I think I am just gonna go ahead and try it.... IT will either burn or it wont and most likely will. But hey, what can I say? Should have thought of it before painting it, guess they should get some touch up paint and hopefully it can be fixed up to look as good.
          if there's a welder, there's a way

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          • #6
            Originally posted by OscarJr View Post
            See what you do is, calculate the time-dependent heat gradient distribution by way of the 3-D heat flow partial differential equation, using welding voltage and amperage to dictate Joule input. Set the boundary conditions to approximate the plate in the immediate vicinity, including the thickness. Find the maximum temperature using aluminum's heat conductivity once you arrive at a peak heat energy transfer to the area in question. Here are the equations:


            2- and 3-Dimensional heat flow







            Man, I loved doing this stuff in college. Pages upon pages of calculations.
            Sounds really interesting, I would like to try doing that equation just for ****s and giggles but the link does not work.
            if there's a welder, there's a way

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            • #7
              Sure it is possible. Get yourself a 110V mig and spoolgun. Load it with industry standard .035 wire and have at it. Surely there won't be enough heat to burn the paint. Even welding the 1/4" plate would be a mystery if it welds...Bob
              Bob Wright

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              • #8
                Machine a dovetail slot in the back and attach the handle mechanically. Or drill a hole to mount the handle with a counter sunk flat head stove bolt and fill the head with body filler so only the head diameter need repainting.
                ---Meltedmetal

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                • #9
                  I know i'm a day late (always a dollar short) but use the spool gun like Bob said and put the painted surface on a frozen wet towel just before you weld it.

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                  • #10
                    Absolutely possible. Just get inside a vacuum chamber, remove the oxide layer from the handle and the spot it needs to be welded to. Press both together and it will cold weld, no heat necessary.
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                    • #11
                      Thanks for the answers guys, ended up adding a dotted rivet type design around the edges of it so just drilled holes and threaded the handle and there, bobs your uncle.
                      if there's a welder, there's a way

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                      • #12
                        If Bob was my uncle, he'd let me in his shop to play with his shaper and all his other cool machines. Then I might learn to run this lathe without ripping some fingers off.

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                        • #13
                          Back when I worked as a mechanic in manufacturing, our safety guy sent me some photos of a guy that got wrapped up in a running lathe. I think the lathe had around a 16" swing, so it wasn't a huge lathe, but there was not much left of the guy, except for his legs. I have a little Grizzly 7x12 lathe, and I respect it just as much as I do the larger ones.

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                          • #14
                            Wow, When you say not much left of him do you mean that literally? I don't have much experience with lathes.

                            My lathe is an angle grinder, a wood chop saw and my arms... sometimes a leg. I still do things primitively.
                            if there's a welder, there's a way

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                            • #15
                              Originally posted by Olivero View Post
                              Wow, When you say not much left of him do you mean that literally? I don't have much experience with lathes.

                              My lathe is an angle grinder, a wood chop saw and my arms... sometimes a leg. I still do things primitively.
                              Here is a LOT MORE.... than you want to see

                              https://www.youtube.com/results?sear...lathe+accident

                              .

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