Re: Inner tubes

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

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

Don't try to fill the tube...
Fill the tube with air, and cover the tube with something that hardens: 
fiberglass, papier mache, etc.

At 12:24 PM 12/12/2003 -0700, you wrote:
>Original poster: "Chris" <ct451-at-yahoo-dot-com>
>I've been trying to fill a 400x8 inner tube, the perfect size for my mini
>coil, with construction foam without any success for a wile now and I was
>wondering if anyone experimented with this idea.
>The first time i tried just spraying some foam inside the tube and letting
>it dry. This didn't work. The foam did solidify but when I removed the can
>air trapped inside came out and the tube shrank.
>Then i decided to puncture a bunch of holes all around another tube and
>then fill it with the foam. This failed as well but got some pretty
>sculptures from where the foam came out of the holes. Again the tube shrank
>non-uniformly even though a lot of foam came out.
>The foam does not set uniformly under pressure and the gasses separate and
>escape.
>For my next attempt I'm thinking of either keep shaking the tube so that
>the gas is mixed with the foam until it solidifies or put the tube in an
>airtight box and suck the air on the outside so that there's less pressure
>inside the tube when the foam expands.
>But perhaps there's a better approach or a different material I can fill
>the tubes with.
>The coil works fine for more than 45 mins on a run with an aluminium tray
>as the top load but it would look so much better with a toroid.
>These tubes cost about $1.50 each and the foam about  $4 for each attempt
>so any help welcome,
>
>Chris