Re: easy tungsten source?

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Ted,

I suspect you will now need to use forced air since there's considerably
less thermal mass and surface area available to remove heat from the
smaller tungsten carbide "Life Saver sized" electrodes than with the
relatively large copper tubes you had before. Can you braze the new
electrodes to larger pieces of metal (copper tubes?) to help serve as heat
sinks? You'll need to remove heat at a sufficient rate to prevent the
working surface of the electrodes from becoming incandescent to prevent
excessive wear and maintain good quenching performance.

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "Ted Rosenberg by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>
> 
> Hi Bert:
> Yes, I believe marc metlika used a string of tc donuts with great success.
> But you mention forced air.
> On my string of 9 sweat couplers, each 1.75 x 2, I used absolutely no forced
> air and it did not seem to make any noticable difference.
> Do you believe the carbide string will demand that I used forced air?
> I have some nice fans I can install in a plenum thing. But if I can get away
> without FAQ (forced air quenching) I'd prefer to keep it simple.
> 
> Safety First
> 
> Ted
> ==============================
> Subject: Re: easy tungsten source?
> 
> Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <bert.hickman-at-aquila-dot-net>
> 
> Ted,
> 
> Tungsten carbide should not present any safety hazard, and some of the
> other coilers on the list have reported excellent results using tungsten
> carbide as spark gap electrodes at low to moderate power levels. If you
> use a string of tungsten carbide electrodes in series, you may find that
> you introduce a bit higher series resistance in the primary circuit
> since the resistance of tungsten carbide is higher than pure tungsten,
> and MUCH higher than the copper electrodes you are replacing.
> 
> Since you're driving the system from NST's, you'll likely see excellent
> long term performance with only a little bit of white tungsten oxide
> after long term operation. Just make sure that you provide sufficient
> forced air cooling for the gap electrodes.
> 
> For high power gaps, tungsten still remains the material of choice.
> 
> Good luck, and let us know how they worked!
> 
> - Bert -
> 
> Tesla list wrote:
> >
> > Original poster: "Ted Rosenberg by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>
> >
> > Bert, all:
> > I'd appreciate a hunch/guess comment if you would on the following:
> > A friend of mine manages a wire hanger factory. In the manufacturing
> > process, steel is drawn thinner and thinner by a series of tungsten
> carbide
> > dies that look like donuts.
> > I bought 9 of these in a suitable size...they are slightly larger than the
> > size of a Life Saver. I will mount them using 1/4-20 brass bolts so they
> are
> > lollypop like, one next to the other.
> > This is to replace my 9 copper sweat couplers which get oxidized badly
> every
> > two-three hours of use at Hangmans House.
> >
> > The donuts appear gray, matte finish.
> >
> > Any ideas?
> >
> > And if the arrangement works as planned, I will tell everyone and I am
> sure
> > that my frien can get more. But they tend to be pricey, about $8 each.
> >
> > Safety First
> >
> > Ted
> > =====================================================
> > Subject: Re: easy tungsten source?
> >
> > Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <bert.hickman-at-aquila-dot-net>
> >
> > All,
> >
> > One other potential problem is that, as with so-called tungsten darts,
> > they are most likely a tungsten-nickel alloy containing 10-30% nickel
> > since pure tungsten tends to too brittle for most common applications.
> > If used in a spark gap some electrode metal is likely to be vaporized or
> > oxidized in operation, and these byproducts may then be accidentally
> > inhaled. The Material Safety Data Sheet (MSDS) for nickel lists it as a
> > possible cancer causing agent (a carcinogen). Similar warnings apply to
> > chromium, making stainless steel an unattractive electrode option as
> > well. Nickel's green and black oxides (Nickel II, Nickel III) also have
> > similar MSDS warnings, along with chromium oxide. They are all
> > potentially quite nasty compounds that you really DON'T want in your
> > body. Fortunately, no such warnings apply to pure tungsten or its
> > oxides.
> >
> > For further information, check out the following MSDS site referenced by
> > Ed Wingate in a post last year:
> > http://www.espi-metals-dot-com/msds.htm
> >
> > Safe coilin' to you!
> >
> > -- Bert --
> >
> > Tesla list wrote:
> > >
> > > Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <Gary.Lau-at-compaq-dot-com>
> > >
> > > One of the design goals in constructing spark gap electrodes is that
> > > they should be reasonably thermally massive, so that the heat generated
> > > at the arcing point is rapidly conducted into the rest of the electrode,
> > > to keep the arcing point as cool as possible.  Should the arcing point
> > > become hot, it will quench poorly and arc at a lower voltage (static
> > > gap) or greater gap separation (RSG) than a properly cooled gap.
> > >
> > > Pen tips are surely very thin and would have a high thermal resistance,
> > > and the arcing point would become very hot.
> > >
> > > Gary Lau
> > > MA, USA
> > >
> > > -----Original Message-----
> > > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > > Sent: Saturday, June 09, 2001 11:11 PM
> > > To: tesla-at-pupman-dot-com
> > > Subject: easy tungsten source?
> > >
> > > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > > <RQBauzon-at-aol-dot-com>
> > >
> > > isnt tungsten used  for some pen tips? if so, would it be possible to
> > > use pen
> > > tips for a spark gap?