Yesterday I built a new tank for Snaggletooth to clean up the surging at the end of tank. While working on it, I dropped My relatively new Weller 100/140 to the floor and broke it. $30 down the tube. I went to Harbor Freight to get a cheaper replacement and found a 180 watt $12.98 gun on sale for $6.98. I bought it.
It didn't work very well at all, in fact, it was next to unusable. It would heat the solder too quickly vaporizing the flux core but was useless at heating the tank sheet metal, so the solder wouldn't flow or wick into seams. After some failed attempts at soldering, I took the gun back to Harbor Freight. It was a complete loser at any price. Actually, I like Harbor Freight and have purchased many tools there including a drill press, chop saw, belt sander, palm sander, spray gun and drill, to name just a few of my purchases. I have been satisfied. The tools aren't what I'd use for commercial work but work well enough for a hobbyist and are affordable.
So, I reluctantly went to Home Depot and plunked down another $30 for another new Weller 100/140 kit. I really hate to pay that for a soldering gun. At home, I was amazed at the difference when using the Weller. Soldering was quick and easy again and the work proceeded fast and smooth. I guess you just need good equipment to make some jobs go smoothly. I try to justify the cost by rationalizing that I use the gun for tanks, shock gears and retaining flap and elevator pushrods as well as occasional general use.
You also need the correct materials. I build tanks from tank tinplate that I get from Brodak. Each time I order they send me about half a dozen foot square pieces of .007 tank sheet metal each of which will make about 3 tanks. Its also necessary to use electrical solder having rosin flux core and a 50-50% lead/tin composition. Solders with antimony just don't work well and using acid core solders or paste flux will rust the inside of the tank while providing no visible improvement in the bond or ease of use.
With a good gun and proper solder the solder wicks easily into joints leaving little visible on the outside surface of the joint. The difference in ease of use may explain why some people are reluctant to try custom metal tanks to fit those unusual applications where plastic tanks just won't work, and hobby shop tanks won't fit.
I've also seen excellent tanks made from soldering irons, that is, externally heated, heavy, heat retaining irons. Never tried one. The Weller gun works too well. I'm not tempted to change. Besides If I had a soldering iron, I'm so careless that I'd probably lay it down hot and accidentally sit on it.
Al