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Re: [TCML] DIY dent-proof Toroids

On 5/27/13 5:15 AM, David Rieben wrote:
First of all, wishing a great Memorial Day to all the fellow US based coilers. Now to my point ;^) I've been following this "DIY dent-proof toroid" thread and I was just wondering.... If you already have the typical "dryer duct" type toroid, could you also not carefully drill a few holes in it in an inconspicuous location (say along the top and near its minor diameter radius) that are just large enough to allow the nozzle of one of those urethane foam canisters to be inserted and backfill the toroid with the foam in this manner? It seems IIRC that this may have been lightly mentioned in a previous post and someone had cautioned the possibilty of the foam expanding unevenly and causing unsightly "lumpiness".? Reason I'm asking is that I already have a huge 12x56 (inch) topload on my large coil and I have already put a good deal of blood sweat and tears into its construction. It was based off some industrial quality 12" diameter flexible duct that was
  purchased from McMaster-Carr. I ended up cutting strips of aluminum flashing and covering the duct surface with the flashing. Adding enough flashing to completely cover the exterior surface of the ducting ended up adding significantly to the total weight, too ;^o (Estimate 30 - 40 lbs total weight now). This has "helped" in dent resistance but it could still be "better". I was wondering if it would be safe to the long term outcome of my big topload if I were to backfill it with that urethane foam? How would one determine how much foam was "enough"? Would like to glean suggestions from the collective advice of this list before investing in 2 dozen cans of urethane foam and/or possibly ruining my huge work of art. :^/


I would try an experiment on a small closed object first. I seem to recall someone trying this before, and there was a problem with suitably venting the gas, and the foam not curing, as well. probably specific product dependent, but you'd hate to have your toroid full of partially cured gloop.

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