Re: Ryobi Bench Top Grinder ??

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Original poster: "Peter Terren by way of Terry Fritz <teslalist-at-qwest-dot-net>" <pterren-at-iinet-dot-net.au>

Hi Ryan - see comments below.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, May 19, 2003 10:11 PM
Subject: Ryobi Bench Top Grinder ??


 > Original poster: "Lannis, Ryan (Ryan) by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <lannis-at-lucent-dot-com>
 > I want to build a new Spark Gap,
snip
 > I was considering using Lexan for my disk,

I have used Lexan (polycarbonate) for angle grinder discs with 6 or 8
electrodes running at a nominal 11,000 rpm. They all eventually developed
radial cracks around the central hole even with the best care in balancing.
Failure = bullets able to penetrate my shed galvanised sheeting. With heat
around the flying electrodes they also creep. No problem since I changed to
a high pressure laminate (Tufnol here in Australia
http://www.bayplastics.co.uk/suppliers/Tufnol-supplier/prod-eng-tufnol(intro
).htm or similar high strength laminates such as G-10 elsewhere). My spark
gap http://members.iinet-dot-net.au/~pterren/tesla_coil_latest.htm

 > One more thing, What makes tungsten electrodes so desirable?  It
 > seems that they wear rather quickly. Why not use stainless steel?

Tungsten has the highest melting point of all metals.
http://www.webelements-dot-com/webelements/elements/text/W/key.html My
stationary tungsten rods go white hot after a short run at 5 kW. They do
wear and oxidise but slower than other metals. I use steel bolts and dome
nuts for my flying electrodes as they are easier to fit mechanically and
only have 1/8 of the wear since there are 8 of them. The radioactive thorium
may also promote spark production but also gives radioactive fallout!

Peter (Tesla Downunder) http://members.iinet-dot-net.au/~pterren/