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Where do I get Tungsten welding electrodes?
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From: Edward J. Wingate [SMTP:ewing7-at-frontiernet-dot-net]
Sent: Friday, March 20, 1998 5:36 PM
To: Tesla List
Subject: Re: Where do I get Tungsten welding electrodes?
Tesla List wrote:
>
> ----------
> From: Mark S. Rzeszotarski, Ph.D. [SMTP:msr7-at-po.cwru.edu]
> Sent: Wednesday, March 18, 1998 4:55 AM
> To: Tesla List
> Subject: Re: Where do I get Tungsten welding electrodes?
>
> Hello All:
> Cliff said in part:
> >I noticed that you mentioned that .38 in tungsten tip rods would be good
> >to use on the stationary part of a rotary gap. Is there any reason that
> >they can't be used on the rotating part of the RSG?
> I have not built a rotary yet but have studied their design. They
> are EXTREMELY DANGEROUS devices, especially if you spin them up over 5000
> RPM which some folks do. The centrifigal forces make them a lethal weapon.
> Perhaps one of the experienced rotary folks can step in here and discuss
> design a bit. A couple of folks on list are experienced machinists who have
> built real masterpieces and understand the need for safety. (Ed, Dave,
> Richard, Bill, Greg, D.C., others step forward at this time.)
> Regards,
> Mark S. Rzeszotarski, Ph.D.
Cliff, Mark,all,
I used the tungsten tipped steel rods sold at welding supply stores to
build a rotor for a rotary gap for a friend. The only reason being that
that's what he wanted me to use! There is a drawback using these as
opposed to the solid tungsten studs that I prefer to use. Since they
only have tungsten on one end, they must be connected together
electrically on a G-10 rotor and the stationary studs must both/all be
mounted on the same side of the rotor. This means each stud must be
carefully drilled and tapped to accept a machine screw to enable
fastening copper straps to the rear side of the rotor studs to
electrically connect each to the next around the whole circumference of
the rotor. Each strap must be the same size physically to keep the
weight the same and the tapped holes in the studs must be drilled and
tapped to the same depth for the same reason to make final balancing of
the wheel less difficult. And balancing is a must for any high speed
rotor. You can use an aluminum rotor to avoid having to physically
connect all the studs together, but this presents the problem of needing
to electrically isolate the rotor from the drive motor. There is also
the possiblity of the tungsten ends flying off the holders if the gap is
overheated sufficiently to melt the braze that connects them to the
steel holder. I have had these buttons FALL off a stationary gap that
was overheated. A good heavy guard should prevent any personal injuries
or fatalities should this happen, no rotary gap should be without one!
And under NO circumstances let anyone stand in line with the rotor of an
operating rotary gap! Almost nothing will ruin your afternoon more
quickly than someone getting seriously injured or killed by a supersonic
piece of tungsten!! This is supposed to be a fun hobby, not a deadly
one!
As I have stated before on this list, I regularly spin the G-10 rotor on
the series-rotary gap on my magnifier system to 7500-8000 RPM, verified
by an infrared strobe tach, with no problems. The rotor on this gap is
1/2" G-10, 11" in diameter, uses 6- .250 diameter solid tungsten studs
and will handle 10 KW easily as attested to by solid 4 minute run times.
I can supply solid tungsten studs in sizes up to 1/2".
I hope this info helps a bit.
Safe coiling,
Ed Wingate