Re: EDM question; light bulbs and resistors

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Marc de Piolenc
<fmdepiolenc@y...> wrote:

>
> Quick note from a lurker:
>
> I don't think that light bulbs and resistors are
> exactly equivalent. A light bulb behaves more like a
> ballast resistore, increasing its resistance with
> increasing temperature. The filament's temperature is
> a function of current, so this makes it in effect a
> damper of current excursions - a regulator of sorts.
> Ordinary resistors are carefully designed NOT to have
> this characteristic as long as the current is withing
> their ratings.
>
> A friend of mine in California built the two-bulb
> circuit years ago and tested it, and it was pretty
> clear that the bulbs were not just passive components,
> that they stabilized the operation of the circuit as a
> whole.
>
> Marc de Piolenc
> Iligan City, Philippines
> (formerly San Diego, California)
>

I built the one bubl version and you are quite right.

The bulb starts with you can barely see a slight internal glow and
then as time progresses, it starts to glow pretty well. If lights
to something of about 1/2 normal brightness when the electrode shorts
into the work.

But, this is not rocket science. This type of EDM will never be
anything more than a homeshop curosity.

The painfully slow metal removal rates limit this to a one project
deal and a very rarely used shop device.

There are metal desintegrators that use verly low voltage and huge
amps as very high voltage and very low amps. As I understand, the
metal desintegrator type bolt remover can drill a 1/2 inch hole into
3 inches of steel in a few seconds.

If one is talking the Langolis EDM then I would offer that this type
of circuit will have a tough time ever reaching the far side of a 3
inch long part.

I have found some design refinements that would make it more useable,
but still the cutting is dead slow.

Jon E. rotated the bit. This concentrated the cutting action to a
very narrow part of the cutter and allows flushing of the hole. This
would make deeper holes much more practical. If you take your
cutter and make the end oval, and tapered, like a funnel, then 90% of
the cutting is on the end, and there is much less electrolosys from
the sides that rob the energy from reaching the end.

on another note, I have a 1/2 tool steel part that I want to get
weire edm's into 4 sections. pretty much just cut down the middle
the long way, then thru the parts that are left.

anybody wanna offer a Christmans present ?

The material is TAUTUNG, a very hard cutting bit for my lathe. I
have a part that is 6" long by 1/2 thick by 1 inch and would like to
have 4 parts, roughtly 3 x 1/2 x 1/2

Dave