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Carbon rod contact resistance

A

amdx

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
 
D

default

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
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

amdx

default said:
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.
Mike
 
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