03-05-2021, 01:19 PM
After my last failed soldering project I looked up shelf-life of soldering flux and concluded that might have been a factor - like yourself I was using (or attempting to use) an old tin of my dad's that had been sitting around for 30 years.
In the past when needy of small scraps of copper sheet I've used central heating pipe - slit lengthwise and batter it flat. Annealing copper is a doddle - hold it in a flame (kitchen stove) until it glows a uniform cherry red then quench it in cold water.
I've read in the past of people using old-fashioned flat irons as a makeshift high-capacity soldering iron in such cases. They will soak up a lot of heat.
Finally, on safety, I'm not sure there's any real way of eliminating all traces of petrol vapour from a fuel tank; at least any task which relies on this should probably be left to a pro. Looking at those pinholes put me in mind of the coke-can bazooka I made as a student, the ignitor hole was just about the size of a pin. We used lighter fuel as a propellant and a tennis ball as the projectile. After several disappointing poots indoors we took it out to the uni playing fields, with a bit more air circulating the resulting explosion threw the ball clean across the cricket pitch (there was a game in progress) and into the trees beyond. I lost all feeling in the tip of one finger for a couple of years. My ears rang for about a week. After that we turned to safer entertainments like letting off outdoor fireworks indoors...
In the past when needy of small scraps of copper sheet I've used central heating pipe - slit lengthwise and batter it flat. Annealing copper is a doddle - hold it in a flame (kitchen stove) until it glows a uniform cherry red then quench it in cold water.
I've read in the past of people using old-fashioned flat irons as a makeshift high-capacity soldering iron in such cases. They will soak up a lot of heat.
Finally, on safety, I'm not sure there's any real way of eliminating all traces of petrol vapour from a fuel tank; at least any task which relies on this should probably be left to a pro. Looking at those pinholes put me in mind of the coke-can bazooka I made as a student, the ignitor hole was just about the size of a pin. We used lighter fuel as a propellant and a tennis ball as the projectile. After several disappointing poots indoors we took it out to the uni playing fields, with a bit more air circulating the resulting explosion threw the ball clean across the cricket pitch (there was a game in progress) and into the trees beyond. I lost all feeling in the tip of one finger for a couple of years. My ears rang for about a week. After that we turned to safer entertainments like letting off outdoor fireworks indoors...