Re: Home-built EDM - plumbing

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Rich" <rmancini@h...> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Rich" <rmancini@h...>

wrote:

> > I just completed construction of a home-built EDM from an article
> by
> > Arnold Gregrich in Home Shop Machinist (October/November 2002).
> > The initial test results were disappointing to say the least.

Using

> > plain tap water, I could hardly get any sparking at all. When it
> did
> > spark, there didn't seem to be enough power to start a hole, much
> > less burn clean through a piece of 1/16" thick steel. I changed
> over
> > to deionized water with no real improvement. The sparks seem to
> > wander and not concentrate in one area.
> > These are the specs: Used two 3600 uf caps, a 400V rectifier and
> 200
> > watt light bulbs in both sockets. The electrodes I tried

were .062"

> > mild steel welding rod, ¼" copper tubing and a piece of a
> telescoping
> > car antenna (chrome plated brass which didn't work at all).
> > If anyone is familiar with this machine, I sure could use some

tips

> > on increasing performance. I need more aggressive sparking, but

how

> > to achieve it is the question.
> > Rich
>
> An update on the Home-Built EDM per Arnold Gregrich's article in
> Machinist's Workshop (Oct/Nov 2002):
> 1. As mentioned in the article, I tried replacing "Lamp B" with a
> fuse.
> This action worked well as I now have an aggressive enough spark to
> actually remove metal where before, none could be removed with a

200W

> lamp.
> 2. The use of deionized water also seemed to help although I'm not
> sure how much.I may also try Kerosene next.
> 3. The best electrode I've tried so far has been ¼" soft copper
> tubing. The biggest problem here has been to get it straight after
> uncoiling it. Mild steel and aluminum (Tig) welding rod didn't seem
> to remove much metal although the sparking action was most

impressive.

>
> I find that you can tell by the sound (sizzling bacon) when cutting
> is most effective and by the production of a very fine "mud" that
> tends to obscure the work piece after a few minutes.
> I think I may be able to rig a pump/filter arrangement to keep the
> water from becoming so cloudy. I'm thinking of an aquarium pump and
> an in-line fuel filter. I've already tried a 12V windshield washer
> pump but it doesn't appear to be strong enough to move the water.
>
> I believe I'm on the right track, but I'd still welcome any
> suggestions.
> Rich

A simple clearing action can be by putting a gallon tank up high and
running a tube down to the cutting location and letting the water
trickle into the work.

when the lower tank gets full and the upper gets empty, just pour one
into the other.

Some large filtering can be done with a paper coffee filter. they
are pretty fine and will clog pretty quickly but the price is right !

Dave