Re: Temporary electrodes for rotary

To: tesla-at-pupman-dot-com
Subject: Re: Temporary electrodes for rotary
From: "Mark Broker" <broker-at-uwplatt.edu> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 07 Mar 2000 11:22:13 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

<snip>

McMaster sells tungsten electrodes for a fairly resonable price.  A 1/8" x
7" long 2% thoriated tungsten electrode costs just over $5.00.  A 5/32" is
$11.31 per electrode!  However, I was told by the University's machine shop
guy (John, actually) that these are *VERY* hard to machine.  An abrasive
saw is needed to cut them (an abrasive tile-cutting saw, for example), and
diamond-tipped or nitrided steel tools are needed to machine them.
However, once cut, the only thing really needed is to de-burr the cut ends,
which could be done on a decent grinder, or even, lacking a grinder, with
some high-quality sandpaper.  Mounting them on the rotary disk is easy:
drill a hole through the head of a 3/8" bolt (axially), and then one
through one flat of the head, tapped, for a set screw.

Although *I* haven't used this setup, I've seen a couple examples of this
on various web pages.

Of course, thoriated tungsten electrodes aren't exactly "temporary," now
are they?

Mark