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RE: fiberglass plastic toroid



Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi Dest:

That's one damn fine looking toroid!  I applaud your use of correctly
shaped pre-cut "lunes" of fiberglass mat.  How did you plot the exact
shape & size?  Well done!

While it's clear that it's possible to build a first rate DIY fiberglass
toroid, it still looks like more effort than many would care to bite
off.  I wanted to mention one further possibility (yeah - a dime a
dozen) for a pre-made toroid.

I've noticed on several occasions in shopping malls, large fiberglass
planters, the top rim of which is a very heavy-duty half-toroid.  Two
such pieces would have to be taped together.  I'm sure they are
fiberglass, as the inside was rough fiberglass mat, but the outside was
perfectly smooth.  I tried in vein to find an imprint identifying the
manufacturer.  I think the largest I've seen would have made something
like a 6"x30" toroid, but if the maker was known, perhaps they're
capable of building something larger, and selling it without the huge
plant pot.

Regards, Gary Lau
MA, USA

> Original poster: dest <dest@xxxxxxxxxxx>
>
> Hallo : )
>
>                              preface.
>
>        "From: Terry Fritz <twftesla@xxxxxxxxxx>
>        Date: Sun, 25 Jul 1999 19:25:09 -0600
>
>        My new aluminum duct torroid came back today with the usual
>        little dings and dents.  They seem to last about three sessions
>        (with car travel) before they need replacement.  Not a big deal
>        but a super resilient torroid would really be nice..."
>
>
> i don`t understand how people can use "bare" ducting at all - it`s so
> unstable in form and easy to dent or bend : ) probably most people
> usually construct something very tiny (like 4" by 18" for example),
> and at this size ducting strength is yet adequate, but when i was
> trying to make 10" by 40" i quickly discovered, that its mechanical
> properties are just crap. maybe it was just a bad luck, or just my
> "armchair coiler" hands growing from wrong place, i don`t know : )
> later i tried to wrap a whole thing with clear scotch tape and
> it helped alot - at least the thing stop bending from its own
> (1.5kg at that time) weight : D it`s even start looking more or less
> smooth:
>
> http://himplast.ru/dest/tesla/toroid/tor30.JPG
> http://himplast.ru/dest/tesla/toroid/tor32.JPG
>
> but i still was able to do noticeable damage just by pressing on the
> surface with my bare finger. after some time i have read on the list
> post from Dr. R., where he quoted prices on spun aluminium toroids of
> various sizes and i laughed very hard about those things -
> "30 inch dia. --- $975.00", and this was bulk order! : D
> then i`ve read that aluminium toroids are rather heavy, and more
> important (as Steve Conner said) - "Some spun toroids dent very
> easily" - heck, and i must pay for thit crap > 500$? NO WAY! : )))
>
> so i decided to do all by myself - i wanted a cheap ducting toroid of
> 10" by 40" that i can kick, throw in the car or store just on the
> floor without any dents. i was looking on the Gary Lau`s foam toroid
> in the past, but i don`t like it - mechanical properties of just pure
> resin coating are poor - it will just crack and shatter if you kick it
> hard. so i decided to go by fiberglass plastic route.
>
> it`s very important to note the following:
>
> 1. i am "armchair coiler" and this was my very first attempt to do
> _anything_ by hands - absoltely NO any experience or even some basic
> skills - you can do MUCH better : )))
> 2. i know nothing about epoxy/fiberglass or such things - only some
> very basic knowledge - the guys who knows some tricks & tips my do
> MUCH better again ; )
> 3. i was not attempting to do it as smooth as spun one - just robust,
> tho after finishing i realized that it would be very easy to
> accomplish.
>
> and here are the results of my very crude attempts % )
>
> http://himplast.ru/dest/tesla/toroid/tor01.JPG
> http://himplast.ru/dest/tesla/toroid/tor02.JPG
> http://himplast.ru/dest/tesla/toroid/tor06.JPG
> http://himplast.ru/dest/tesla/toroid/tor07.JPG
> http://himplast.ru/dest/tesla/toroid/tor08.JPG
>
> note that i have not even try to grind joints yet, not to mention
> polishing the whole surface. how it looks on the top of the "coil":
>
> http://himplast.ru/dest/tesla/toroid/tor13.JPG
> http://himplast.ru/dest/tesla/toroid/tor22.JPG
> http://himplast.ru/dest/tesla/toroid/tor23.JPG
> http://himplast.ru/dest/tesla/toroid/tor24.JPG
> http://himplast.ru/dest/tesla/toroid/tor25.JPG
> http://himplast.ru/dest/tesla/toroid/tor26.JPG
>
> here are some results of the first unsuccessful attempts in finding
> right proportion of resin:catalyst:accelerator, right time for soaking
> glass fibre mat in resin and trying to cover the ducting evenly:
>
> http://himplast.ru/dest/tesla/toroid/tor03.jpg
> http://himplast.ru/dest/tesla/toroid/tor04.jpg
> http://himplast.ru/dest/tesla/toroid/tor05.jpg
>
> but there were only 3 errors, so i ruined only 2 piece of mat (from
> total of 32) and 225 ml of resin (from total of 3600 ml) so it`s ok.
>
> now the most fun part - dest_ructive testing : )))
>
> 1. http://himplast.ru/dest/tesla/toroid/kickin.avi
>
> i`m laying some thick linoleum on the floor, laying toroid on it and
> trying to kick it with my feet : ))) there is only 10 fps, so video
> is not showing real dynamics of the kicks - they are looking a bit
> "slow" and "soft" - that`s not 100% correct. and btw - this thing
> weigh 4.5 kg - just try to kick such mass on soft thick linoleum.
>
> 2. http://himplast.ru/dest/tesla/toroid/knockin.avi
>
> i`m taking a hard wooden block with srarp edges and trying to make
> some dents by knocking on the surface - listen to the sound of this
> knocks : ))) unfortunatelly i failed to demonstrate the sharpness of
> the edges - stupid camera fixed it`s focus right after pressing
> "record" button.
>
> 3. http://himplast.ru/dest/tesla/toroid/squizin.avi
>
> here i`m putting small sheet of thick (1 cm) acrylic right on the
> toroid and then put a 30 kg variac on this sheet! it`s somewhat hard
> to see the weight of the variac in video, so i took one still for ya:
>
> http://himplast.ru/dest/tesla/toroid/tor27.JPG
>
> you may hear some cracking in the backgroung - don`t worry - that`s
> not my toroid : ))) it`s just a debris on the floor - you can check it
> when i walk away/to the toroid - the same sound.
> why i put those 30 kg so slow? coz i placed acrylic a little askew -
> you can see how the variac trying to fall towards the camera : )
>
> conclusion - even the most lame "coiler" can make very light (4.5 kg),
> very strong (your kids can take it to fool around with it on the
> river : D), very cheap for its size (total cost was about 120$ - here,
> in russia, where ALL components that i used was imported)
> 10" by 40" toroid. and i think that even John Freau would never be
> able to do something as big and ugly as i did : )))
>
> -----
> Let the bass kick! =:-D
>