Thanks for the post, and turning us on to that channel. Neat stuff.

Successful larger jobs, like a fuel tank requires a smooth flow of solder along a seam, maybe 4 to 6 inches in length. In cases like this, the work piece absorbs a great amount of heat energy, which must be spread over a large area.  The usual soldering gun tip cannot replenish lost heat fast enough to complete a large area joint without stopping and completing the soldering seam in stages.

I saw a pretty neat trick for soldering irons (actually guns) the other day, in an old radio restoration context. In this video:



Paul "Mr. Carlson's Lab" Carlson has a radio and electronic repair/restoration channel. His videos are well-made, with great production values, and he is pretty sharp  - and also very long-winded (and based on his experience on Antique Radio Forum, more than a little nuts). Anyway, he shows a pretty neat way to hop up your Weller or other soldering gun - shorten the tips.

    He shows replacing the tip entirely with a short length of 1/8" solid copper wire. The effect is that the resistance is greatly reduced, increasing the current, and thus making it get much hotter much faster. I tried that, and it worked, but was a more than a little excessive for any modeling purpose.

      For a less extreme but still pretty impressive increase, take the regular tip and cut it off as much of the "tails" that go into the gun as you can without reshaping it.  Mine were cut off about 1/2". While you are at it, file the ends of the tails back to bare copper all around, and then reassemble. This proved plenty enough to quickly solder 1/8" music wire with great ease. It would have done it eventually with the normal tips, but this just about zapped it on there, less than 5 seconds. Heating it this quickly can be important, because it takes less total heat if you do it quickly, and the heat doesn't soak back into everything else nearly as much.

   Of course, you could do it more by bending it, but mine is quite a bit better even with a very conservative change.

    What this does to the longevity of the iron is debatable but after talking to him off-line, it seemed that he has been doing this for a long time and had no failures. Using a slightly-improved system is of course less stressing than his extreme version.

     It's probably more than you need for tanks, but for heavy soldering, this seems to be a big improvement.

      Brett