Re: [CAD_CAM_EDM_DRO] EDM questions

Mark,

cool, I've been wanting to try to make one. I'll tell
you a couple of things I know about.

If you are feeding the cap and rectifier with 230VAC
you better get a higher voltage bridge and cap.
Rectified 230 is 325VDC.

another thing is that you have to do is current limit
your circuit charging your cap. I'm sure you already
have this. controlling the speed the cap recharges is
going to be one of the factors that determine you cut,
another is the gap/voltage applied and the cap
size/current. I have looked up on the Internet an seen
at least one diagram of the gap voltage peek at around
100v. different systems my very and it may also depend
on the gap.

Lastly I've read that the gap is very small between
the electrode and workpiece and edm machine have very
small resolutions to try and regulate the gap size. I
don't if you can do that by hand. Maybe if you attach
a screw to the press to feed it very slowly.

I'm curious about what you are using for a dielectric?
I was wondering about just using water based
solutions. I know there not the best but I was
concerned about the safety factor of using flammable
liquids.

Please let us know how things are going :)

Larry


I you are rectifying 220
--- Mark Stacey <pav@...> 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. I've modified the design
> slightly to use
> what is avalable. It's fed by 230V 50cycle single
> phase (standard
> houehold current in New Zealand) The capacitors are
> 680uf 250v. Bridge
> rectifier is rated at 250V 20amps.
>
> 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?
>
> Can anyone sugest what I can switch across the
> output leads to drain
> the capacitors after I've turned the EDM off? I
> don't want to
> accidently discharge the capacitors through the CNC
> or for that matter
> myself.
>
> Cheers
> Mark Stacey (Still tingling)
> www.cncprototyping.co.nz
>
>
>
>
>
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