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RE: [TCML] 8" Secondary Woes
Sonotubes go by the inside diameter, but measure every 8" tube in the rack!!! There are 2 different sizes when you buy Sonotubes for shipping purposes. You could have two 8" Sonotubes that measure o.d. differently. One 8" tube will fit inside the other 8" tube. They do this to minimize shipping costs because they don't care if you have to pour more concrete to fill it up as long as it's at least 8" inside. Good luck with your build
Rich Domsicz
Prototype Assembler
FLEETWOOD
P. 610 916 9999 F. 610 916 9900 C. 484 226 0992
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-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Jon Danniken
Sent: Tuesday, September 03, 2013 11:41 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] 8" Secondary Woes
Have you considered using a concrete former tube, such as Sonotube product? They come in an an eight inch size, although I'm not sure if that is the OD or ID (if the latter, you would be winding on an 8.5" OD tube).
It will obviously take more work, as you need to dry and coat the tube before using it, and you will probably want to provide a finish on the exposed parts of it to look nice (maybe use a wood laminate on the exposed surfaces).
Jon
On 09/03/2013 07:29 AM, Greg Peters wrote:
> 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!
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