Because they're rubbish and they never worked well.
You might get these to work on steel, although the resultant "brazed" joins are brittle and weak, owing to over-heating and the resultant dezincification. On aluminium, forget it.
The distinction is subtle and pretty minimal, that's for sure.
Brazing requires a generalised heating and a filler that flows by capillary action. Take the same base materials and filler rod, but use a smaller, hotter arc or O-A torch and you have bronze welding. The heating is localised and the filler rod is worked in a pool, not just flowing under its own volition.
Ah. Thanks for the explanation.
Not IME. I always use carbon arc brazing for building up metal or joining thin sheet steel without the problems of arc welding when not using mig. I find it quite a forgiving process and have not found problems of brittle joints.
Regards Capitol
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