Re: EDM questions

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Richard" <phrh@w...> wrote:

>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mark Stacey" <pav@x> wrote:
>
> My two cents worth---I believe that the lightbulb /rectifier power
> supply is similar to the one I suggested to Dave Mucha some time

ago.

> Dave mentions a resistor is required, the light bulb is the
> resistance and the RC combination across the electrode/work gap(
> which mimics a gas tube) supplies a sawtooth voltage (relaxation
> oscillator) for the spark. It is my opinion that the capacitor size
> (within limits) is not too important as the frequency changes
> according to the RC constant and the cutting rate is controlled.A
> large capacitor slows down the rate but blasts off a larger chunk

of

> the workpiece due to the higher current spark, a smaller C

increases

> the spark frequency but balsts off a smaller chunk of the

workpiece

> so that the time to cut a hole is pretty constant. My EDM is

adjusted

> so that the electrode never touches the work always maintaining a
> gap,
> and sparks instead of arcs! I use tap water containing a bit of
> permanent antifreeze and it works well using a drip system right

down

> the electrode to flush away debris. Richard

I used a small diameter brass tube and put a 45 degree bend in it.

Then soldered it to a connector to make an electrode with a hollow
core.

I connected a tiny tubing to it and let the water drain. At first,
it drained quickly, but as the electroe wore away into the part, the
gap reduced and so did the water flow.

The tiny electrodes I saw on e-bay had a center spoke so that if one
were to rotate the electrode, it would remove the core.

Dave