Re: Wire ECM

--- In CAD_CAM_EDM_DRO@yahoogroups.com, wthomas@... wrote:

>
> Hi Graham and All:
> I have a few of these also. Only I call them white throne ideas
> as that is usually where there are formed. One of them goes along
> with your Wire ECM idea. I had thoughts of adapting a wire EDM to my
> CNC mill for the XY movment but was going to have to add a traveling
> wire to the system. Your ECM w/o the traveling wire could work great
> on a vertical CNC mill. You could put the wire holder in the chuck
> on the Z axies with a tank clamped on the table. Then go for it with
> the chemicals and power. Let us know how yours turns out as I think
> this would be great for thin metal stencals.
> GOD'S BLESSINGS
> Bill
>

Since thinking about it some more I am not sure it is such a daft
idea. And I think you are right about the "add-on" potential.

When compared to EDM, ECM has some real advantages. The supply is low
voltage and high current, the control is much more simple and the
chemicals are well just salt. Then there is the everlasting electrode
I have just discovered that sodium nitrate is better for precise
applications because the deplating rate increases with current density
for that salt, this means the closest parts get eroded first gaps can
be less than 0.05mm. It also means the gap gets smaller for higher
machining rates so faster better parts. The difficulty for the
homebrewer as far as I can see is that the gap must be flushed very
well, this means a decent forced displacement pump. Filtering is easy
and the salt itself is not used up you just need to top up the water
levels. I recently stripped down a super cheap pressure washer, it
has a three piston swashplate driven pump that MIGHT offer super cheap
fast flushing with perhaps a toned down motor. (don't ask me why I
stripped it down but yes I was considering buying a second)

I once called ECM the poor mans EDM, I'l not sure really but it has
potential for sure.

Thin sheet cutting might be OK if you insulated the electrode well
above and below the sheet, you could probably varnish the top of the
sheet lightly as well, flushing would be very easy at least, not much
of a gap to flush. Speed could be VERY fast if the wire can take the
current that could be helped by putting the wire through thick blocks
so it is only thin in the cutting zone.

I'm setting up a webpage about EDM and ECM as I type, I want to stick
some of what I am learning down on electronic paper.

Graham