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Inside fillet and outside corner back to back on aluminum

Posted: Wed Feb 15, 2017 5:49 pm
by bruce991
Welding an inside fillet weld after doing a outside corner weld on 3/16 aluminum flat. Seems I do the inside fillet and the nice outside bead gets hot enough to become concave? Back off on amps I presume on the second weld? Let piece completely cool before attempting welding on opposite side? I am experimenting and would like to think I could do both sides without damaging one of them. I had piece on a heavy steel milling set up block as a heat sink.

Re: Inside fillet and outside corner back to back on aluminu

Posted: Wed Feb 15, 2017 5:58 pm
by AndersK
When heat soaked you need a lot less current to weld the second string even on a thick piece. The melting temp is far lower than steel but heat conductivity much higher so you need a lot more juice to get started.

Re: Inside fillet and outside corner back to back on aluminu

Posted: Wed Feb 15, 2017 6:01 pm
by exnailpounder
If your piece gets hot, it will take less amps to weld it. Thick steel isn't a great heat sink. I will draw out heat but very slowly so thats why your AL stayed so hot. If your not in a hurry then let it cool off between welds or quench it. Are you using filler on your OS corner weld or fusing?

Re: Inside fillet and outside corner back to back on aluminu

Posted: Thu Feb 16, 2017 8:16 pm
by bruce991
exnailpounder wrote:If your piece gets hot, it will take less amps to weld it. Thick steel isn't a great heat sink. I will draw out heat but very slowly so thats why your AL stayed so hot. If your not in a hurry then let it cool off between welds or quench it. Are you using filler on your OS corner weld or fusing?
Using filler moving along quickly. Last two times I did this while practicing I believe I did outside first then inside. So probably should let cool, or do outside last backing down on amps, maybe no filler I guess. Just need to practice more on scrap pieces. Learning more every day. Today's lesson did vertical up on 1/4 inch aluminum went pretty good.

Re: Inside fillet and outside corner back to back on aluminu

Posted: Sun Feb 19, 2017 1:19 am
by 5th Street Fab
We usually try to do the inside first, then we cut out the burn through and weld the outside. It's nicer looking in the end.

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Re: Inside fillet and outside corner back to back on aluminu

Posted: Sun Feb 19, 2017 6:02 pm
by bruce991
5th Street Fab wrote:We usually try to do the inside first, then we cut out the burn through and weld the outside. It's nicer looking in the end.

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Okay will try inside first. And probably let cool then outside kind of a fast pass. Figure the inside fillet can tolerate the heat a bit better than the outside.