Re: [CAD_CAM_EDM_DRO] EDM? Was: Phase Control of SCR's; Hi Curren t

: )
If this is meant to be an incredibly precise method doesn't opening the
middle of the tube mean the arc has an edge it can jump from rather than the
centre of the rod? Or does it keep in the centre still because of something
to do with the dielectric actually passing through it? I think something
even better than EDM for reading about has to be ultra-high pressure
machining. Those things sure put out something! 40,000 psi! I can blast
stuff about my garden with the 100 psi washer! They had them firing glass
bead media for cleaning the muck off ships hulls (Even out of dry dock and
underwater. That'd be an interesting job). Then they fed this sort of hose
firing this water / media mix down a sewer pipe line that had about an 1 - 2
inch of stuff stuck to the walls in a video. The pressure blow that much
crap off it look better than metal straight off the roll, it was soooo
shiney. How do they actually get the water to such a high pressure? Because
the pumps look pretty small, are they using screw compressors or pistons?
And more to the point, how do you hold them when they're firing something
with over 200 times more force than yourself?

John

----- Original Message -----
From: "Jon Elson" <jmelson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, March 05, 2001 10:46 PM
Subject: Re: [CAD_CAM_EDM_DRO] EDM? Was: Phase Control of SCR's; Hi Curren t


>
>
> dave engvall wrote:
>
> > e.heritage@... wrote:
> >
> > > It appears to be so neglected by hobbyists who want to make their own
> > > because it's quite a tricky thing to get going I've read. The second
guy I
> > > mentioned had to start it up, cut a tiny hole, stop, back it up, wash
out
> > > the dielectric, bring it back down, drill, stop, bring it back up....
etc.
> > > I'm not sure how far you could take it as a hobbyist if you wanted to
build
> > > your own. I'm pretty sure it'd take about three minutes to solve the
> > > problems with the dielectric from the talents I've seen on here so
far. The
> > > guy was saying he couldn't find any hollow electrode thin enough, so
he
> > > couldn't pump the fluid down it. I'd just try pumping it straight down
the
> > > sides of the electrode myself, you've seen the You Only Live Twice...
> >
> > Dave....just out of lurk mode:
> > Unless you drill really small holes the hobby brass tubing should do
the job. According to the liturature one does well to spin
> > the rod AND inject dielectric thru the rod to flush. One article I read
(either "EDM today" or 'MMS" was using really high pressure
> > dielectric and it not only flushed but stabilized the rod in the hole
for less wander of the wall. IIRC 1000 psi was in the right
> > range. They also drilled deep holes very quickly; like 0.040 500 thou
deep in a few minutes.
>
> Yes, I was the guy who "couldn't find hollow electrodes", but that was
late at night, digging
> in my junk box. I needed to burn out a couple of broken taps in parts.
The hollow tubing
> in the K&S displays at the local hobby shop are just right for this.
>
> Jon
>
>
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