Analog Angle Article

Irons in the fire. . . .literally

Sometimes you have to go through a hands-on experience to really understand what a clichß or stock phrase really means. Take, for example, our many phrases centered on having a lot of “irons in the fire.”

The other day, an email from a friend mentioned that the term “soldering iron” in the modern electronics context is a misnomer, an anachronistic hold-over from the days of real soldering irons; and we should really use the term “soldering tool” or “soldering instrument.” Yes, he's right, but will we change our terminology? I don't know, but it's unlikely.

But his email reminded me that the previous owner of my house left me three real, old-fashioned soldering irons with wooden handles, ranging in length from about 12 to 15 inches (30 to 38 cm) and with the iron part (the head) of different sizes and masses as well, click here. (Hmmmm. . . .maybe they are worth something as antique tools?–I'll have to check into that!).

Since it was a nice day and I was looking for a small, no-brainer project under the guise of “research”, I fired up the charcoal grill using real hardwood charcoal, not the more-common, cooler-burning charcoal-and-clay briquette matrix. After about 30 minutes, the charcoals were glowing nicely; by various means I estimated the temperature at about 375° to 400°F (190° to 205°C) a little above the pile, so the pile's core was somewhat hotter.

So I put the irons in and did some modest fooling around. It took between 5 and 10 minutes for the irons to get hot enough to melt standard 60/40 solder with its melting temperature of 370°F (about 188°C)), with the smallest iron getting there quickest, of course.

But the most revealing part of this exercise was how long, or short, each iron was able to maintain that required temperature. The largest iron could melt the solder for about five minutes, the smallest one could do about three minutes, Of course, in a real application of trying to solder actual metal and not just melt a string of solder, their useful times would be far less, as the thermal mass of the load draws heat out of the iron so much more quickly. So to solder a seam of roof flashing, for example, you might only have a minute or two of useful working time per iron.

Result: you need to work fast and have a lot of irons in the fire, and just managing all those irons affects your ability to get the job done quickly. It's a lot easier with an electric- or hydrocarbon-fueled tool, that's for sure.♦

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