Re: resistance soldering
- It helps to be an electronics engineer. It is, of course, abysmally easy to make a very good resistance soldering unit, especially if your electronics toy bin has a few simple items in it.
For power, one only requires a lower voltage high current transformer. This can be between 6 volts and 10 volts, but should be capable of at least 20 amps current. Ham radio operators use these all the time and they are a drug on the hamfest flea market. A simple 500 watt defective computer UPS has a good high current transformer in it. If run in reverse, these can usually supply up to 20 amps at 14-28 volts from a 120 volt line.
For control, either a variac (variable line voltage transformer) or a simple triac phase controller circuit. Just a few components are needed.
The interesting part is the hand piece/tweezers. Even this is also a snap, especially if you have a simple lathe and drill press. This assumes you can actually use these machine tools with some skill.
Carbons are commonly found at some better welding supply stores. These carbons can be machined easily as well for varying tips and size needs.
With a good electronics junk bin and a few simple machine tools a 0-300 watt variable system could cost a good bit under $40.00, but you will have to have a decent number of hours in the build.
I think I'll give this a shot. I have several brass locos, but don't have an immediate or pressing need, but still it would be good to have a resistance unit on hand.
It boils down to whether you have a good deal of money or a good deal of time with some skills. For some here, $300.00 is no big deal. For others, that money could have so many better uses than to be spent on something used infrequently.