Re: filling toroids

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

Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org> 

Ian, and others:

I wasn't planning to fill the toroid, actually, and really wasn't too 
interested in other types of foams.  I only want to "partially fill" 
it.  For instance I just made a standard 4" drier duct toroid last night 
(4x16.5")  I was thinking that I could mount the toroid vertically 
(horizontal axis) in a lathe (or some motor).  I could pour some epoxy 
through a smallish hole on the inside of the toroid by using a funnel.  I 
would only add about 3 inches worth of epoxy.  I could then turn the lathe 
on "highish" to spin the epoxy to the outside via centrifugal force until 
the epoxy sets (perhaps an hour or two)  When the epoxy hardens, it has 
filled the big crevices in the periphery of the aluminum drier duct, 
preventing damage where it is most likely to occur.

I bought an extra 4" duct to experiment with and have another back in the 
shop at my alma mater with the rest of my TC in progress.  If the Society 
of Physics Students left the epoxy from their canoe-making around, I'll try 
this and maybe a variation, and report back on Monday.

TTYL

Mark Broker
Chief Engineer, The Geek Group


On Thu, 08 Jan 2004 11:42:02 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Ian McLean" <ianmm-at-optusnet-dot-com.au> I have used 
>polyester resin before (LSE - Liquid Styrene Epoxy, used for
>fibreglassing).  Whilst it works quite well and dries rock hard (I used it
>to pot the ceramic capacitors in my NST filter), it does get quite hot
>during curing, and also shrinks in the process.
>
>I worry that the polyester would melt an inner tube during curing, and also
>shrink out of shape.
>
>Another alternative I just thought of would be an encapsulant.  Something
>like isophorone diamine (used to pot MKT capacitors, etc.)  This stuff does
>not heat up during curing and does not shrink.  It moulds perfectly (it is
>designed to).  Trouble is, it is very expensive.
>
>Also, a toroid made of solid epoxy, of any sort, would be very heavy, yes ?
>
>Rgs
>Ian.