Re: Tungsten

["Jim Lux" <jimlux-at-xxxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Tesla list wrote:
> 
> Original poster: "Garry Freemyer" <Garry-at-NDFC-dot-com>
> 
> I am alittle concerned about the Thoriated type. Thorium is a radio active
> element that emits mainly Alpha radiation I believe. It decays into other
> isotopes, I don't remember which. It's been a VERY long time since I studied
> this subject but I am concerned about the thorium becoming vaporized and
> being breethed in. In fact, I wonder how they get away with the thorium in
> the white gas lamps I am so familiar with.

In the lamp mantles, it is thorium oxide (and cerium oxide, and some others
as well).. and it doesn't vaporize at all.  Thoria's melting point is well
above the flame temperature, and what you actually get the light from is
the thoria heated to around 2800-3000K (literally white hot)...

Interestingly, domestically manufactured mantles don't use thorium any
more, probably because of the perception(!) of a rad hazard, you have to
find the ones from India.  Take that geiger counter to the store when you
go hunting for them.. The actual hazard is miniscule (unless you breath or
eat the mantles) but there is a somewhat irrational fear of "radiation"
among the general population.

> 
> Maybe it's not all that dangerous or maybe thorium isn't vaporized as the
> white hit temperatures of a lamp.
> 
> Alpha wave radiation if strong enough might cause sunburn, wouldn't
> penetrate much deeper than the skin If that deep, but if it were deposited
> in the lungs this would be a different story altogether.

Thorium is a beta emitter... Goes right through the plastic bag holding the
mantle..

There is a company making special TIG electrode grinders with filters, etc.
just to accomodate those who fear the 2% thorium.  As a practical matter,
you don't get much exposure (laying the electrode right on the window of my
geiger counter doesn't even raise the background count).  Thorium isn't
particularly active (i.e. it has a long half life, and you need a lot of
thorium to get a decent disintegration rate).  You probably get more
exposure from the radium and uranium in granite, or from the potassium 40
in the body of the dog, cat, or spouse sharing your bed.

> 
> Anyone have any thoughts on this?
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Thursday, November 02, 2000 12:00 PM
> To: tesla-at-pupman-dot-com
> Subject: RE: Tungsten
> 
> Original poster: "Ted Rosenberg" <Ted.Rosenberg-at-radioshack-dot-com>
> 
> Finn:
> As I have said before (with a smile) get 10 coilers together, ask one
> question and you get 12 answers. And probably all 12 are right.
> 
> I have seen posts that say that using a hacksaw takes muscle, time
> and...more time. Yet you find it no trouble. Today, I received mail from
> Scott Hanson who cautioned that the thoriated version was not as good as
> pure tungsten. And that the pure variaty was OK as is.
> 
> I guess the best approach is to try what you think will work and if it does,
> wonderful. If not, try something else. Like building a tank cap for $10 <big
> smile>.
> 
> I will surely post the results of my electrode operation. Any bets folks?
> 
> Safety...and Goggles
> 
> Ted
> 
> Subject: Re: Tungsten
> 
> Original poster: "Finn Hammer" <f-hammer-at-post5.tele.dk>
> >
> > Original poster: "Ted Rosenberg" <Ted.Rosenberg-at-radioshack-dot-com>
> > snip
> > Once you get the rods you'll have to look into a method of
> > cutting to the desired length. I have a Dremel Diamond Cutting Wheel
> > ($21.00) on order.
> 
> I have said it before, and I will say it again:
> 
> It doesn`t take more than a couple of minutes, to cut a 5/16" rod of
> 2%thorium/tungsten with an ordinary hacksaw, equipped with an (around)
> 30 teeth per inch High Speed Steel (HSS) blade.
> 
> There are fancier methods around, but this is the one I resort to every
> time still.
> 
> Once cut, mount the bits in an electric drill, and rotate them with it,
> while you press the end of the electrode-to -be against a grinding
> wheel, or a belt sander. Be garefull if you use a grinding wheel, it
> tends to knock the electrode/drilllingmachine back untill a nice true
> surface is obtained.
> 
> Hemispherical ends are rather easy to make this way too, and for static
> gaps, my favourite, the Rukowski lookalike profile (big radius across
> most of the surface, progressing into a nice small radius blending into
> the shaft) -Not too hard to make.
> 
> Cheers, Finn Hammer