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Re: Tungsten vs. Tungsten Carbide

Tesla List wrote:
> 
> >From mycrump-at-concentric-dot-netSat Nov 23 20:07:58 1996
> Date: Sat, 23 Nov 1996 20:10:01 -0500 (EST)
> From: "Daryl P. Dacko" <mycrump-at-concentric-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Tungsten vs. Tungsten Carbide
> 
> I spent several hours today playing around with my arc lamp
> power supply and some tungsten rod and a tungsten carbide lathe
> insert to see which faired better in a torture test.
> 
> I hooked up a 5/32" pure tungsten tig welding rod to one stand
> and a 1" long by 1/2" wide by 1/4" thick diamond shaped tungsten
> carbide insert to the other stand. I adjusted my arc lamp supply
> to 15 amps and struck an arc. I waited until the tips burned back
> enough to put out the arc and then reversed polarity to the tips
> and restruck the arc and let it burn until the arc went out again.
> 
> Total arc time was close to ten mininuts (sp).
> 
> The tungsten rod burned back about 3 to 4 times as fast as the
> carbide insert and left a pretty yellow deposit of tungsten oxide
> crystals around the rod.
> 
> The carbide insert burned back only 1/8 of an inch and left very
> little deposit on the tip.
> 
> By careful guesstimation, and use of my DVM, I'd say that I'd have
> about three ohms more resistance in each tip useing a carbide tip
> than using tungsten rod, which might work out to only losseing
> five watts or so more than using rod.
> 
> I think I could build an effective holder for these tips by slotting
> an alunimum bar and drilling a thru hole to fit the 3/16" hole in
> the tip.
> 
> These carbide tips look better all the time !
> 
> Has anyone else tryed carbide tips in a rotary ?
> 
> Daryl


Daryl -

  I sure have. Used the round disks that I silver-brazed onto brass
studs. In all honesty, they ablated (wore) away very quickly. I had
used 3/8" round tips. I now use 3/16" pure tungsten rod, which is
smaller, and ablates a bit more slowly. From what I understand, if you
can cool the electrodes down a bit, they last longer. I plan to put
a high-velocity blower nozzle on my gap to cool things down.

- Brent