Re: ECM, The poor man's EDM??

> Op's I had assumed a unitary electrod on the end, not one that

would

> be intermitant.

You have to have some insulator with the gravity feed method or it
will short.

> If it were unitary, then the time of etching would be constant,
> whereas a small say, 10% section on the side, would etch at a much
> slower rate.

You have lost me to be honest.

> Another not about rotating, if you use an tube type electrode and

have a wire across the end, there will be no stub left as the unit
will cut it out. This will take longer of course, but the wire
would allow flushing.

They do that with EDM, they have a twisted divider in the tube, as
the electrode disapears the bar effectively rotates removing the
part of the workpiece that had been left. For ECM a wire od
something might be good however unlike EDM, ECM does not have the
spark gap problem, the plug that forms will be removed as it
progresses. However it will slow the cutting rate as it will take
current away from the small gap area at the tip.

Idealy I would be able to take a normal copper tube or an EDM
electrode with some internal walls and dip the end in some magic
goop. The goop would dry as a tough but porous insulator. Then the
walls of the tube would be insulated with varnish or even heat
shrink. This would allow side ways machining at a rate fast enough
for fast downwards machining. The insulation properities would
prevent shorting while the porousness would allow current flow in
the electrolyte and machining.

Graham