Wire EDM Power Supplies

Listers,

First time out.

I want to build a simple, robust and cheap one axis Wire EDM machine
to cut off hard materials like tool steel. A cut rate of 0.050
inches / minute is fast enough for a 1/4-inch thick piece of stock.

I'd like to know if anyone here knows what the power supplies are
like on a typical small wire EDM machine. What is the waveform that
is normally used? What are the Amps and Volts? I'll be using
distilled or de-ionized water and the parts will be submerged.

If someone can supply these answers it would be much appreciated. Or,
failing that, if someone could direct me to where I can find some
information on this topic.

I've done a search on your Archives, but did not turn anything up,
unless I missed it.

Tried posting this before, but it may have gotten hung up somewhere.

Arch