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

I am trying to do ECM, in EDM they use a tubular copper electrode
with internal flutes, they then spin it, this means the workpiece
sees a solid electrode even though the dielectric is being flushed
through it. In ECM it is a little different, especially in my
gravity feed version. I am trying to use insulating parts on the
electrode to set the gap while still allowing ECM action. I suppose
this could alsow be done in EDM however and it is a big however.
The electrode in EDM is also eroded so whatever clever trick you did
would have to adapt with the constantly shortening electrode. In
ECM the electrode does not degrade.

I even tried wire ECM of sorts with a stiff wire electrode and some
glass fibre braid (allows electrolyte and current through but does
not allow short circuit), it does work however I thing I was getting
arcing as eventually the braid would get holes in it. This might be
corrected with better filtering of the electrolyte.

A good ECM link:

http://electrochem.cwru.edu/ed/encycl/art-m03-machining.htm

please have a read everyone, this could be very cool.

Am now thinking a simple current monitoring z-axis maybe the way
forward.

Graham



--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...>
wrote:

> Graham, I was at a tool show the other day and they had an EDM

type machine that did exactly what you are describing. Not sure what
they are using for an electrode. It looked like a brass rod. I
talked to them breifly and the machine was for starter holes. It was
only $20k..:-)

>
> Ron
>
> Graham Stabler <eexgs@n...> wrote:
>
> You can use a rotating electrode where the insulator extends

beyond

> the conductor but only intermitantly, that way as it rotates the
> workpiece sees the electrode for half of the time (say).
>
> The supply needed is just a DC supply, for what I was doing

something

> along the lines of 40v 5A is fine.
>
> Graham
>
>
> >
> > If I can envision what you are saying, the insulation prevents

the

> > hole from being larger than the electrode, that is until the

bottom

> is
> > cut deep enough that the sides start to be eroded.
> >
> > What about a rotating electrode, with one point that is a

conductor.

> > 90% of the cut would be down, 10% sideways.
> >
> > Easier than EDM ? what type of power are you using ?
> >
> > Dave
> >
>
>
>
>
>
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