Re: [CAD_CAM_EDM_DRO] Re: Wire ECM

1000A/sq in is needed to remove a bulk of material
quickly. But just as with a taig, one does things on a
smaller scale with hobbyist equipment.
ECM is just plain slow but there is little that can
rival its precision.
i once drew a tube of an eyedropper so fine that
gravity was overcome by the capillary- with this- i
was able to drill a tiny hole in a copper penny inside
of the loop of the 9 on the date. it took overnight
cuz of no outrageuos current densities and the actual
cathode was way up in the eyedropper. But say you just
LIKE having tiny holes in copper...
Therefore i will offer ENCOURAGEMENT to anyone wishing
to experiment with it. it is tremendously easy to do
exceedingly fine etching and marking on things lasers
will have trouble touching and for which you won't
easily find the tiny tools available any other way.
do it and find out. :) THAT's where the fun is! ECM is
probably the only way a hobbyist can actually put
angels on pinheads.

--- Graham Stabler <eexgs@...> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, jesse
> Brennan <jkbrennan@...>
> wrote:
> >
> > I have an old copy of a 250 page monograph on ECM.
> >
> > Tool materials are called out as copper, brass,
> bronze , stainless
> > steel, a copper - tungsten alloy for close gaping
> , and 12% Chromium
> > steel. For deep hole production-- titanium. no
> graphite use is
> > mentioned.
> >
> > Current densities are quit high-- about 1000 Amps
> per square inch.
> > To remove heat flow velocities of the
> electrolyte may range
> > from 50 to 100 feet per second.. In practice
> 100fps is more
> > normal. pressures are quite high ( Maybe 500
> psi) and the force
> > between tool and work is about the same as in
> conventional machining.
> >
> > These indicate that a home built machine is
> probably impractical.
> >
> > I know people have done home electroetching for
> thin part production
> > ( stencils etc) but this not to the same detail
> and extent as
> > produced by true ECM.
> >
> > jesse
> >
> >
>
> Any chance of a copy or is it paper only?
>
> Considering I have made some holes with ECM myself
> using windscreen
> washer pumps and the like I am not quite ready to
> throw the towel in
> on the process. If we were to quote the vital
> statistics of any
> commercial grade CNC machine we would think it
> impossible to homebuild.
>
> One way to reduce pressure requirements is to
> retract on a more
> regular basis, bad for industry but good for us.
> The parts produced
> in the link I sent seemed to have been made on a
> machine based on very
> regular retraction.
>
> I almost forgot, I did actually try a form of
> wire-ECM last year, the
> idea was to make a device for cutting hardened
> shafts in situ. I took
> some strong wire and put a piece of fibreglass braid
> over it. I hung
> the wire over the test shaft (a milling cutter) and
> applied a constant
> flow of salt water and some electricity. The braid
> allows the fluid
> to pass while preventing a short circuit. It did
> sort of work but the
> process definately needed some refinement, I suspect
> the main problem
> was the size of the gap being too large and the lack
> of real flushing.
> It might have made sense to make the wire move
> between two reels like
> a band saw.
>
> Graham
>
>
>
>
>
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