[pianotech] Center Pin Zapper

[David Boyce]

It seems to me that a zapper made from two soldering irons, and one made 
by electric current, are two different types and may have different effects.

In both cases, the intention is to heat the center pin.  In the case of 
the soldering irons, the heat is generated in the center pin by 
conduction from the very hot tips of the soldering irons.  In the case 
of the electric method, the heat in the pin is produced by letting a 
large electric current flow through the pin, causing it to heat.

Now, with the soldering irons, the heat will spread from the ends of the 
pin towards the middle, This means that the bushings will be heated 
before the birdseye.  With the electric current method, might not the 
pin heat from the middle of the pin towards the ends? In that case, the 
birdseye will feel the heat before the bushings.

It's my understandting also that DC is much more dangerous than AC.  And 
that it's amperage rather than voltage that tends to be deadly.

The whole business of heating center pins by passing electric current 
through them seems fiddly and frought with problems, to me!

David Boyce