Re: EDM questions

Thanks to all have replied this is all very helpfull.
The circult shows two light bulbs. On the positive lead from the
bridge rectifier the bulb is before the positive leads of the two
capacitors. On the negative lead from the rectifier the second bulb is
placed between the two negative leads of the two capacitors. I'm using
150watt incandescents.
I've tried both water and kerosine as dielectrics. Not much difference
in results.
My mill has a fairly fine resolution as it is retro fitted with a
Centroid full servo system so that looks to be the next step after
wiring a resistor and a double pole switch so when the mains is off it
discharges the capacitors.
Thanks once again, lots to try!
Cheers
Mark Stacey
www.cncprototyping.co.nz


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

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mark Stacey" <pav@x> wrote:
> >
> > I've built an EDM from the article in Machinists Workshop Oct/Nov
> 2002
> > pg 24 to 26.
> > I've been testing it out using my drill press and get either violent
> > pops every second or so or I end up with the wire I'm using spot
> > welded to the work piece.
>
> <snip>
> >
> > Will most of the problems disappear if I use the slow feed on my CNC
> > mill rather than a nervious hand on a drill press?
>
>
> There are a few solutions.
>
> #1) rotate the electrode. this will prevent the huge loss thru
> electrolicys as the electrode goes deeper.
>
> #2) create a step generator and comparitor loop. Monitor the current
> and when it is under X amps, step. Between X and Y stop lower than
> Y it would reverse and also step.
>
> This would be in combination with a screw that would feed something
> like 20,000 steps per inch or some very fine feed.
>
> #3) lower the cap to under 20uF caps in series will reduce the
> capacatance if you have a bunch of them. Switching them in and out
> will offer some selection.
>
> I don't recall the circuit, but as someone pointed out, you need to
> have a resistor between the power supply and the cap. This limits
> the cap charging time. A 100 watt lightbulb sould do. Incandescent
> please. Rated for the AC voltage.
>
> Dave