Megatroids - construction of a 48" by 18" toroid
- and how to extend it to 72" by 18"
Following others on the list I made my first small toroid using a plywood disc and foam pipe lagging - about two inches diameter I cut a slit in this to the centre and wrapped it round the disc using wire to hold it in place, I then used aluminium tape to cover it all for an 18" by 2" toroid.
The little toroid in action.
My second toroid uses 4" diameter Aluminium ducting - this comes as a 1 meter long tube that can be extended to 3m. I cut two plywood discs 2 foot diameter and then covered one side with aluminium foil - fixed with wood glue. These board were then fixed one inch apart, using a couple of pieces of wood. I then stretched the ducting around this wheel. (I would fix the plywood discs 2 inches apart in the next one. Easier to fit)
I had passed a wire and one of those stretchy luggage rack ties through the ducting to hold it in shape (next time I'll use a piece of chain so that I can easily alter the tension.
It is fiddly to stretch and shape the ducting material - two people would be better.
I had drilled holes though the edges of both plywood discs, about 1/2" in and 6" apart I passed wire though the holes and round the ducting to secure. I also used wire to tie the ends of the ducting together and used Al foil tape to cover over the join, I soldered the wire joints for permanence.
For those in the UK (and else where) the 4" ducting is available from B and Q. RS components have different style of ducting. A toriod based on this can be seen on the Bride of Frankenstien page. The prices given are in UK pounds (multiply by 1.5 for rough US dollar prices).
Ducting Fibreglass - would need covering