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Re: [TCML] 8" Secondary Woes

Some good information on PVC dimensions for various "Trade" sizes and Schedules...



On Sep 3, 2013, at 10:09 AM, "AusTesla" <austesla@xxxxxxxxxxxxxx> wrote:

> I found the same thing.  That is why I am doing a 10" coil as mentioned just
> previously, because this was the next size available up in PVC stormwater
> from 6" here in Australia.  I fell into the same trap - the pipe is marked
> as 225mm but I don't know for the life of me where they take that
> measurement from - the inside diameter is greater than that at just under
> 240mm, and the outside diameter (5.5mm thick PVC) is very close to
> 10"/250mm.
> So you can't even trust the markings on the pipe itself!  Luckily for me I
> haven't wound my primary yet.
> Cheers,
> Ian
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of Greg Peters
> Sent: Wednesday, 4 September 2013 12:29 AM
> To: Tesla Coil Mailing List
> Subject: [TCML] 8" Secondary Woes
> Hi all,
> Well I've done something stupid. I wound a beautiful spiral primary with a
> 12" diameter inside turn on nice polycarbonate supports. I assumed that I
> would be using an 8" (200mm) secondary and that 8" was a standard pipe size.
> I was aiming for 2" between the primary and secondary. Never assume
> anything! The nearest PVC water pipe OD is either 160mm (6") or 250mm (10").
> 8" OD tube is as rare as hens teeth in Australia. The only exception is 8"
> acrylic tube which is difficult to cut and work with. I'm not a big fan of
> acrylic, as I always seem to get my saw stuck, etc and I can see my
> beautiful former being destroyed.
> I have called nearly every pipe and plastics supplier in the country and I
> am out of luck. No polycarbonate, styrene, PVC, polyethylene, polypropylene
> or other plastic in 8" OD! I even called some of the gas pipeline suppliers
> - I CAN get a length of blue 200mm LDPE pipe for about $500....not ideal
> (expense wise).
> I noticed that McMaster Carr has very cheap polycarbonate tubing in 8" OD,
> and placed an order only to be informed that they will not ship to
> Australia. There are a few other not so cheap US suppliers who may be able
> to assist if necessary though they seem significantly more expensive.
> Anyway, the closest thing I have found in Oz for a reasonable price ($200)
> is a length of orange PVC electrical conduit at 225mm (9") OD.
> So, my question to the list. Do I persist with trying to find an 8" tube,
> possibly even from overseas, or settle on the 9" conduit and tolerate having
> only 1.5" between my primary and secondary? I expect I will need to lift the
> secondary quite a bit to prevent overcoupling and even flash overs from the
> primary which will be running 24kV. Is anyone else running a largeish coil
> with this kind of spacing?
> This was meant to be a museum quality build and the idea of having to
> significantly lift the secondary is frustrating, but realistically it's
> looking like the only option! The coil has been painstakingly designed to
> sit exactly in the middle of my shed space for maximum spark length in all
> directions. Oh well, next time I will be more careful and assume nothing!
> Cheers,
> Greg.
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