Re: Home-built EDM

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Marcus and Eva"
<implmex@a...> wrote:

> Hi All:
> You don't want much conductivity in the dielectric.
> What you do want is just enough conductivity and close enough

proximity

> between the workpiece and the electrode that a controlled amount

of current

> at a predetermined voltage will jump the gap and knock a bit of the
> workpiece away as it does the jump.
> The dielectric is ionized locally in the process, both by the

energy of the

> discharge and by the contaminants that are produced by the erosion

of the

> workpiece and electrode.
> Commercial wire EDM's go to great lengths to get the ions back out

of the

> dielectric (they mostly use water as a dielectric) so it won't be

too

> conductive.
> The conductivity should be such that several amperes at 30 odd

volts is

> needed to traverse a gap of roughly 0.001", and should stay that

way as much

> as possible throughout the burn.
> Dumping salts into the water will make it far too conductive to

work.

> Cheers
>
> Marcus

This is espically true for an RC circuit. the conductivity of the
dielectric can prevent the cap from charging.

In this months EDM rag of the trade, they are offering cleaning of
your EDM fluid. you ship out your old stuff and they will clean it
and return you stuff 'as good or better than new'

For us garage and basement guys, water works acceptably. and as Jon
advised, some solutions work much better.

Dave