Re: Thorated vs Pure Tungsten

At 10:19 AM 6/16/99 -0700, you wrote:

>You can get small solid metal balls with threaded holes in them quite
>easily. look for any of the following: solid brass drawer pulls, lamp
>finials (the ball on the top of the harp), etc....  They also make threaded
>steel balls (and Alum too) for the knob on the end of machine tool handles.
>McMaster Carr almost certainly has them, but so should a "machinery" dealer
>(a place that sells real tools, like mills, lathes, etc.)
>ball bearings are really, really hard, and because they are curved, it is
>hard to drill a hole in them.

I can' drill or file ball bearings.  They ARE REALLY REALLY HARD!!!!!  I
can easily grind a flat on them (electric hand grinder) and solder them but
the solder may melt and drop off the ball which would be "bad" for a safety
gap.  I imagine they would make a very good arcing surface...

>Any particular reason why you want steel?

I was looking for something that would never wear out.  I can be hard on
safety gaps :-))

>> I definitely would stay away from thorium and other radioactive
>>electrodes.  Pure tungsten is supposed to wear faster but the worry of
>>radioactive dust getting in one's lungs during the difficult cutting and
>>grinding of this gnarly material out weighs that.  "Playing" with the pure
>>tungsten is far better than worrying about dust particles from the thorium,
>>or cesium, or lanthanum...  Some claim good wear from non radioactive
>>alloys of tungsten too, but this is getting to be too complex as it is...
>Cesium? I would expect cerium, a rare earth used in arc electrodes, flints,
>etc. Cesium is like sodium, potassium, etc.  soft, low melting point, very
>very reactive..

Yes... I should have said cerium not cesium....  Actually, these are all
oxides of the metals too.  This is out of my area of expertise, but I am
learning fast!!