Re: foil-covered inner-tubes for large toroids?

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Original poster: sparktron01-at-comcast-dot-net 

Hi David

-------------- Original message --------------

 > Original poster: DRIEBEN-at-midsouth.rr-dot-com
 >
 > Hi all,
 >
 > I've been thinking of an affordabale alternative to a large
 > pofessional spun toroid for a large coil. I've heard of sev-
 > eral ideas, including the chicken wire covered wood and styro
 > foam skeleton frames. I almost certain that my idea is not
 > original, but I was wondering what you guys thought of a
 > large inflated tractor tire inner tube covered in alumi-
 > num foil or tape. Of course it would be imperative that it
 > didn't leak and I know that the small inner tube lined pneumatic
 > tires (wheelbarrels, 2-wheel dollies, ect.) are notorious
 > for slow leaks. My 2-wheel dolly tires always have to be in-
 > flated before use if I haven't used it in a while. Hopefully,
 > tractor tire inner tubes are somewhat more dependable for
 > holding air as I'm sure a farmer wouldn't want to always
 > worry about his tractor tires holding air. Has anybody had
 > experience with this approach at a large toroid?
 >
 > Thanks,
 > David Rieben
 >

Richard Hull used a very large inflated donut (may have been a kids

swimming pool) on Nemesis originally.  Cold weather will cause a

reduction in internal pressure, and the tape will sag...  :^C

Best option was 4" (and larger ) flexible PVC drainage pipe available

at Lowes, Tractor Supply, Home Depot, Agri-Suppliers.  Use a coupling,

cover liberally with Al tape and go.   I've made several large toroids

up to 4 x 42" this way and they work fine; plus if you drop or impact

them they "usually" won't permanently dent.  FWIW.

Regards

Dave Sharpe, TCBOR/HEAS

Chesterfield, VA. USA