Re: [CAD_CAM_EDM_DRO] Re: EDM troubles

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
>>
>>
>I'm using water, well water, so I have no idea what is in the stuff
>other than calcium and a little iron. Once it goes past the house
>filter the salt is supposed to replace the calcuium so I figured on a
>greater conductivity with the house water.
>
>
>
>>How are you advancing
>>the electrode? It is VERY sensitive to MICROSCOPIC movements.
>>I use my CNC system, which has encoder resolution of .000025"
>>
>>
>
>I'm using a Xylotex on a 400spr stepper on a 10tpi leadscrew. with
>the Xylotex set at 8x microsetpping, that come out to 0.00003125 so
>ware are in the same neighborhood.
>
>my step logic is not tuned as yet, but a 1/2 step worked pretty well
>and that would be 0.000125, but you are correct. most people don't
>understand that you can move the head of a mill by putting weight on
>it.
>
>
>Bottom line, water = hydrocarbons = insulation on electrode = need
>for cleaning.
>
>
>

I don't know how you figure there's carbon in your water. There should
be darn little
hydrocarbons in well water. But, there certainly is "stuff" in it after
a little EDM
burn. And, exposing the electrode to air after a burn might cause very
rapid
oxidation. I never had any of this with my rotating electrode, though.
That
worked very well. I suspect a gravity-fed flushing arrangement would work
even better, though. I have some small bore tubing I picked up at the hobby
shop for the next time I want to do this.

I used alum-tap as my EDM fluid, and it IS a hydrocarbon-based material.
It definitely turned black, but I think most of the black stuff is atomized
metal from the taps I was burning out, not carbon. Note, this stuff is
flammable, but I was using very small amounts (a couple drops at a time
in blind holes). I have had it flash exactly once, and it was a little puff
of flame about 1/2" in size. I did have a big fire extinguisher handy, just
in case.

Jon