Re: EDM troubles

> Dave,
>
> EDM electrodes take time to 'bed in' so that there is uniform
> contact across a wide area, rather than just at one point. Even
> rotating a circular electrode it takes time for the current to

come

> up to the calculated value on my commercial die sinker edm

(Eurospark

> H425).
>
> I suspect that maybe you have raised your electrode, and lowered it
> in a slightly different place (rotationally perhaps) so what was
> bedded, no longer is.

This is defintely possible. My clamp is not very strong. my first
part moved every time I raised the electrode. I felt I wasn't
getting anywhere unitl I pulled the part out of the fluid. huge
crater all over the place.

> Flushing the gap makes an enormous difference to the rate of

cutting

> by both carrying away the eroded material and ensuring correct
> discharging conditions rather than arcing. I always pump fluid
> through the electrode if the shape permits.
>
> Interestingly, fresh edm fluid is less effective until it gets a
> small build up of ionised debris in it,

I observed this also, needed to not flush for the first couple
seconds and from that point, it was fine.


Dave