On Wed, 16 Nov 2005 17:41:50 GMT, Ignoramus7434
wrote:

The constant current welder adjusts the voltage, up to a certain
amount, and down to almost zero, to produce desired current.

Plating wants a voltage of around 6-7V, with good control of current.
This isn't a "constant current" source, because if it does vary (owing
to workpiece conditions changing) then it's better if the source behaves
as a constant voltage source, once set. Current needs good manual
control though and is a crucial adjustment for plating.

Some processes want higher voltages: 12V for hard chrome, 16V+ for
anodising and some quite high voltages for anodising titanium.

I've also not seen a welder that went down to this 6V level.

If I short the leads of the welding machine, the voltage drops to
almost zero.

I'm pretty certain that it _is_ zero. The welder will detect this as a
specific case and go into a "shutdown" condition.

We live in a world full of cheap scrap electronics. I just wouldn't use
a welder for this, when I have any number of small compact 5V and 12V
high-current PSUs just looking for new homes.


Right. Right now I am mainly interested in derusting, using steel
electrodes, which is environmentally safe.

Car battery charger (old non-auto one). You only need maybe 5A tops at
12V for anything that fits in a dustbin. I've done boat hulls where I
used an old computer PSU and about 60A.