Re: Inner tubes

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

Original poster: "pjj" <tha3rdman-at-zoominternet-dot-net> 

Chris,

   I have "played" with construction foam in my past, and found that the
stuff in the cans is not worth your time. I tried filling plastic bags with
the stuff and as you said it not only seperates but also doesnt set, (think
its air dry). BUT i have looked at alternatives, marine foam is 2 part, and
therefor may not need air to cure . . .maybe ;)

Paul
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, December 12, 2003 2:24 PM
Subject: Inner tubes


 > 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