Re: Electrode holder was Terry - "Improved" propeller gap design

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mark Broker by way of Terry Fritz <teslalist-at-qwest-dot-net>" <mbroker-at-thegeekgroup-dot-org>

I do, actually.  It should have been uploaded by now to:

http://hot-streamer-dot-com/temp/RSG%20picture.jpg

The rotor is a 10OD x 1/2" thick Grade LE disk mounted to the
motor with a turned aluminum hub.  The electrodes are all 5/32"
diameter 2% thoriated tungsten, all 6 from one 7" piece from
McMaster-Carr.  The 3/8" brass bolts have a slightly oversized
hole drilled through the center.  The set screws are 4-40 round
head machine screws set in a tapped hole through the bolt head.
I don't remember why I used only one per bolt, though I think
breaking a tap was one reason. . . .  (I found out later while
cleaning up the shop that the drill bit I used was misplaced, and
was a #45, not a #43 :o  )  I faced the set screw outwards to
facilitate gap spacing adjustment.  Since brass is a little
"sticky," I would presume this helps secure the tungsten
electrode as well.

There is an aluminum annulus set into the disk on the back side.
Not the best choice, electrically, but it saved me about $20.

Also, FWIW, the gap spacing is about .030" nominal, and I have to
turn the variac up to about 100V before it will arcover, even
with the motor off and the gap adjusted to min spacing by hand.



1/28/2003 8:59:32 AM, "Tesla list" <tesla-at-pupman-dot-com> wrote:

 >Original poster: "Mark W. Stolz by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <mark_w_stolz-at-hotmail-dot-com>
 >
 >Mark,
 >
 >Do you have any pics of these electrode holders?
 >
 >Mark Stolz
 >Houston, TX
 >http://teslacoils4christ-dot-org
 >
 >
 >>Original poster: "Mark Broker by way of Terry Fritz
<teslalist-at-qwest-dot-net>"
 >><mbroker-at-thegeekgroup-dot-org>
 >>
 >>If the "clamping slot" is made through the entire length of the
 >>hub, then no fancy machining process is needed - only a hack
saw.
 >>I see no real advantage to using such an elaborate design.
 >>
 >>As for set screws:  FWIW, I used 4-40 round head machine screws
 >>as set screws on my standard rotary design.  A #21 hole was
 >>drilled through the center of the bolt using a lathe, in which
 >>the 5/32" tungsten was insterted.  I couldn't remove a tungsten
 >>rod if I had to without loosening the screw, even after many
long
 >>runs and months of sitting in the closet.
 >>
 >>Mark Broker
 >>Chief Engineer, The Geek Group
 >>
 >>
 >><snip>
 >
 >
 >