filling toroids

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

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

So we have learned through experience that pretty much every attempt to 
fill a toroid with expanding foam has resulted in an unusable 
mess....  Have people tried other substances?  For instance I was thinking 
that the typical aluminum drier duct toroid is most susceptible to denting 
of the ridges along the rim of the major diameter.  Perhaps partially 
filling the toroid with a thinner 2-part epoxy (cures via chemical reacion 
- not air) and spinning it fairly slowly until it cures would make for a 
much more dent-resistant toroid?

I was planning to try that this weekend but was hoping someone had already 
tried it.  I don't suppose anyone has found an easy way to smooth the bumps 
of aluminum drier ducting that doesn't require several layers of fiberglass 
and countless hours of sanding?  The masking tape still leaves a pretty 
bumpy surface.

Thanks,

Mark Broker
Chief Engineer, The Geek Group