I'd say that the carbon has much less resistance than the steel. Heat
I don't know the relative resistances, but the carbon rod turns red long before I can get the iron/steel to glow. Could be a mass thing, my rods are pointed. The color changes starts right at the point of contact and moves up the carbon rod. Mike
What's that Lassie? You say that Leo Lichtman fell down the old sci.engr.joining.welding mine and will die if we don't mount a rescue by Sun, 25 Oct 2009 09:22:02 -0700:
If the holder lacks a lever to move one of the rods into the other, then you touch both to a metal object to create two arcs, than as you pull away they will merge together. You can also use another carbon rod to start the arc.
The point of contact has the most resistance due to the small contact area, so it gets hotter faster. All the current goes through that small spot.
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From the Lincoln manual:
Thickness of Current(A) Carbon base metal diameter
1/32 30-50 1/4 1/16 60-60 1/4 1/8 70-80 5/16 1/4 90-100 3/8Note that the chart is oriented towards how much current to use for particular base metal thickness, but also does correlate to carbon size.
Bob
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