Tungsten vs. Tungsten Carbide

To: tesla-at-pupman-dot-com
Subject: Tungsten vs. Tungsten Carbide
From: "Daryl P. Dacko" <mycrump-at-concentric-dot-net>
Date: Sat, 23 Nov 1996 20:10:01 -0500 (EST)

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