Re: [TCML] rotary gap disk

[Scott Kraus <plymouth_4406@xxxxxxxxx>]

If the metal disc was mounted directly on the shaft and supported on pillow block bearings and driven with a belt you wouldn't need to have an insulating hub. The belt material would have to be chosen carefully as some are somewhat conductive to reduce static buildup. Of course the assembly has to be mounted on insulators. It all depends on what materials you have to work with.
 
Scott

--- On Sat, 11/29/08, David Rieben <drieben@xxxxxxxxxxx> wrote:

From: David Rieben <drieben@xxxxxxxxxxx>al
Subject: Re: [TCML] rotary gap disk
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Saturday, November 29, 2008, 1:23 PM

Hi Ed,

Well, I can think of one reason many ametuer coilers
haven't tried the metal disc on a dielectric hub. That is
many of us don't have immediate access to profession-
al quality lathes, end mills, drill presses, ect. that would
pretty much be essential for fabricating the RSG that you
propose. Of course, I suppose the more familiar G-10
and tungsten RSG would also require quality michining
to fabricate properly as well, but it seems to me that
matching and securing the metal disc to the high dielectric
center hub would prove a bit more of a challenge for the
"shade tree" machinist than the more traditional G-10 disc
with tungsten flying electrodes ;^) I guess it's just a matter
of personal preference.

David Rieben


----- Original Message ----- From: "Ed Phillips"
<evp@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, November 29, 2008 12:30 PM
Subject: Re: [TCML] rotary gap disk


> Acrylic is a very poor choice for an RSG disk.  As you observed, it is
brittle and would be dangerously stressed in an RSG application. Polycarbonate,
a.k.a. Lexan, would be a better choice, but still not as good as G10, as Lexan
will soften if the electrodes heat up.
> 
> If one has limited machine skills and equipment, a propeller RSG is a very
good alternative to a disk.  See mine at
http://www.laushaus.com/tesla/sync_gap.htm
> 
> Regards, Gary Lau
> MA, USA"
> 
> There have been countless discussions like this in past times and I always
wonder why guys don't use what, at least to me, seems the obvious and almost
certainly cheapest choice.  That is a metal disk with insulating hub of almost
any material since the tensile stress will all be in the metal and the hub will
remain cool.  An additional advantage of the metal disk would be additional
cooling due to conduction away from the electrodes.  I know some of the members
of this group have used such designs and "in the good old days of
wireless" almost all spark gaps, up to many kW power levels, were made that
way.
> 
> Ed
> 
> 
> _______________________________________________
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