Re: EDM questions

--- 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