Re: Home-built EDM

The dielectric used in an EDM is not highly conductive.

adding just one tablespoon of salt to a 50 gallon tank can raise the
ph considderably and also effect the conductivity. distilled water
is sought for this work as it does not offer the imputities that
other solutions have.

that said, as soon as one starts EDMing metal, the metals that are
suspended effect the conductivity in the localized area of the work.

Dave





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Kenneth Emmert"
<mds1878@c...> wrote:

> I just completed construction of a home-built EDM from
> an article by
> Arnold Gregrich in Home Shop Machinist
> (October/November 2002).
> The initial test results were disappointing to say the
> least. Using
> plain tap water, I could hardly get any sparking at
> all. When it did
> spark, there didn't seem to be enough power to start a
> hole, much
> less burn clean through a piece of 1/16" thick steel. I
> changed over
> to deionized water with no real improvement. The sparks
> seem to
> wander and not concentrate in one area.
>
> Rich
>
>
> First I have no experience with EDM. Though I do have
> excellent experience in getting water to conduct
> electricity. Simply adding table salt will
> dramatically increase conductivity, say 10% by weight.
> Pure water will not conduct electricity, simply test
> with a multimeter. Commercially sodium potash or Lye
> is used to increase electrical conductivity. In a
> ratio of 30 to 50% by volume though these are caustic
> solutions.
>
> Ken
> Kenneth A. Emmert