Re: Electrode holder material for a high-power RSG

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve Cook by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Steve-at-g8cyerichmond.freeserve.co.uk>

The use of beryllium seriously worries me. Beryllium is a potent carcinogen,
and whilst in a non breathable state it is no problem, but the dust and
oxides formed are breathable.
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 11, 2001 6:29 PM
Subject: Re: Electrode holder material for a high-power RSG


> Original poster: "bob golding by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<yubba-at-clara-dot-net>
>
> Hi Mark,
>     Just guessing here but I don't think it sounds like a good idea to
have
> beryllium alloys
> anywhere near a spark gap. Beryllium oxides are very toxic. The rotary
will
> spread it around
> liberally I would think.
>
> cheers
> bob golding.
>
> Tesla list wrote:
>
> > Original poster: "Mark Broker by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <broker-at-uwplatt.edu>
> >
> > Hello, all
> >
> > I am making an RSG that I hope to one day (years away) use with a big TC
> > (25kVA) at 3600RPM (thinking 5kRPM *MAX*), though I'll be starting with
a
> > 1200RPM motor (min speed).  Since I have the resources literally at my
> > fingertips until this May, I thought I'd build this puppy now.
> >
> > An AutoCAD drawing of the whole rotor can be seen at:
> >
<http://mbroker.tripod-dot-com/TeslaCoil/SRSG.jpg>http://mbroker.tripod-dot-com/Tes
> > laCoil/SRSG.jpg
> >
> > That's a 12" Dx1/2"thick G-10 rotor with 12 electrodes on a 10"D circle.
the
> > idea is that the electrode assemblies will be precisely the same lenght
(from
> > electrode tip to electrode tip) and as symmetric as possible.  They can
be
> > removed from the rotor by removing the single set screw, and replaced
just as
> > easily.
> >
> > A picture of my prototype electrode assembly can be seen at:
> >
<http://mbroker.tripod-dot-com/TeslaCoil/Electrode_holder_Prototype.jpg>http://
> > mbroker.tripod-dot-com/TeslaCoil/Electrode_holder_Prototype.jpg
> >
> > (turns out the elctrode is 8mm, not 5/16", so they won't fit into the
> brass w/o
> > using a hammer, which I don't want to do just yet.)
> >
> > The holder is 1"Dx 2.10"long brass (don't know what kind - but it wasn't
an
> > "easy machining" type - lots of tool chatter).  The  "spacer" between
the two
> > "fins" is .50"D.  FTR, I'm going to remove the 45deg taper on the first
"fin"
> > of the holder.  I also have to tighten up the lathe a bit - too much
play
> which
> > led to much imprecision.
> >
> > So, anyways, I was concerned about the .5"D brass being a weak point in
the
> > system (copper is about 5 times more conductive than brass).  I fear
that if
> > I'm operating a high power TC with a high bang size that the resistivity
> of the
> > brass will cause undue heating and I^2R losses.  I did some searching
> > throughsome catalogs, and found at McMaster Carr a copper alloy that
> appears to
> > be the ticket item:  Copper Alloy 182.  It's virtually lead free, and
> contains
> > .6-1.2%by wgt chromium, which adds a lot of strength and high
temperature
> > stability.  The down side is that it's a LOT of money.  Alloy 172 also
> seems to
> > be a good bet as it's supposed to be spark-resistant, and even harder
than
> > 182.  I uploaded the PDF file explaining the alloys here:
> >
<http://mbroker.tripod-dot-com/TeslaCoil/3238.pdf>http://mbroker.tripod-dot-com/Tes
> > laCoil/3238.pdf
> >
> > What are you thoughts on my design?  What are your thoughts on using
this
> > material for this purpose?
> >
> > Thanks, guys!
> >
> > Mark B
>
>
>
>