Re: stepper edm

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@...> wrote:

> What I noticed was that the surface darkened in a large section
> around the hole. This too lead me to believe the electrolysys was
> draining away the energy.

I don't think the amount of electrolysis was increasing rather the
amount of material you could see had been effected by it did. If the
resistivity of the water was enough to do the EDM then I don't think
you would loose much energy via the small direct currents between the
wire and the material. It would depend to some degree on if you were
recycling the water or down-the-sinking and on the flushing etc. Heat
build up in the water will also slow cutting which is why wire EDM's
have coolers. Water is good for the reasons of low viscosity and good
cooling but you have to take the heat somewhere.

It seems more likely that the difficulty flushing caused a build up of
swarf, perhaps even coking and that can cause a job to come to a stop
never mind slow down.

Spinning the electrode especially one with a "cutting tip" does sound
a good idea. I wonder if you might get especially good results in tap
burning by using a rectangular strip of copper rotating. It describes
a cylinder as it spins has a decent surface area but you can do the
really easy flushing with a pipe you mentioned. Actually some of the
tubular electrodes I have used had a little bar inside, one supplier
used to sell them with a twisted bar so that even without rotation you
would get better flushing as the eroding face of the electrode
"rotated". I wonder if rotating a twisted strip of copper with the
twist in the correct direction would augment flushing by screwing the
dielectric into or out of the gap, that would be worth a try.

> and, yes, it was water. working in a basement, I have very litle
> ventilation.

Same in my attic! Something I had forgotton about when I was
considering switching to oil, at the moment I am using distilled water.

Graham