Re: Inner tubes

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

Original poster: "Brian" <ka1bbg-at-webryders-dot-net> 

Hi, I think both Gary Lau and i both tried the foam in a tube.. i could get
it to harden but never a nice round donut. the foam just is not made to do
what we want. maybe if the form was hard and strong it might work. Gary had
one machined from foam. cul brian f.
----- 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
 >