I just finished soldering a #6 wire to a copper connector. I am out of propane see used a carbon rod and battery charger to heat the copper connector. All worked well, but now I wonder, all the heat starts at the contact point. Is there somthing about carbon that causes a high resistance at the contact point? Does it matter what it is contacting? Thanks, Mike
Carbon rod contact resistance
Feb 08, 2008
2 Replies
I have a soldering set from the 50's that consists of a largish open core transformer and a set of carbon rods. It is a good way to solder heavy things like auto radiators.
Carbon/graphite is a semiconductor and has a relatively high resistance compared to metals - the size of the contact point and current available determine the heating.
Does it matter what it contacts - yes won't work on insulating material obviously. Doesn't work so well on steel - at least my device doesn't. Good for heating non ferrous metals.
A few years ago I walked my son down to car dealer that had large beam of light traveling across the night sky. It was an old search light on a truck with a generator. He described all about it and the carbon rods used in the carbon arc. It used two diameters, 3/8" and 5/8" IRC. The smaller one was tapered towards the end and caused a concaved shape in the larger one. Anyway he gave me
4 or 5 used rods 3" to 5" long. I recall useing one to heat a difficult to remove nut, that worked well also. MikeJoin the Discussion
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