Re: Sonotube used as a removeable form for Fiberglass coil form?

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Original poster: Greg Leyh <lod@xxxxxxxxxxx>

Hi Jim,

I've done it that way a couple of times, with 
good results. The first one was wound on a 36" sonotube form, shown here:
http://www.lod.org/Projects/electrum/construction/pages/winding.html

To accurately support the sonotube on the winder, 
we made a metal strongback for it:
http://www.lod.org/Projects/electrum/construction/pages/chiptrus.html

After applying a 3/4" fiberglass wall with a chop gun, it looked like this:
http://www.lod.org/Projects/electrum/construction/pages/coilxprt.html

The second time was on a 24" form, for making two 
matched 24"x94" windings. Rather than shoot the 
external wall however, we inserted the 
windings+sonotube into an external casing and 
potted it into place, then removed the sonotube. 
Finished secondary looks like this:
http://www.lod.org/Status/90L10KPhotos.htm

All in all, fiberglass casings work well for TC 
secondaries. Make sure to use the fire-retardant 
grade however, if you plan on processing large 
amounts of power. Also, plan on supporting the 
sonotube internally to support the weight during 
fab, unless the sonotube will be wound and glassed in a vertical position.

-GL


> Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
> Hello all,
>
> Has any one ever made a fiber glass coil form 
> from a sonotube. ( to be removed). I followed 
> several telescope threads where this has been 
> effectively (10? 0r 12?). I want to make a 20 to 
> 24? coil 4.5 to 5 ratio. Yea! I have access to a 
> near by barn and lots of interest with my 8.5? 
> coil. There is hope for my marriage after all.
>
> Recent skin effect verses conductor dia threads 
> have hedged that there is a sweet spot. This 
> coil will be wound with 12 Gage solid core house 
> wire. Home Depot has it in 2500 rolls. The 
> prelim cacls suggest this coil would have a self 
> res of 84KHz. Stranded mics @ .128? x 1000 
> turns= 128?/12= 10.666 ft coil height with a 24? 
> diameter we get a 5:1. I am still using Classic Tesla Java.
>
> If some of you have time run a sim on this for 
> efficiently on this coil parameter the primary 
> (pancake) is to be ½ tube 1.5 ? arc space to the 
> Secondary, separated by 3/8? turn to turn, 
> Capacitance will be smallish at first (.03 to .8 
> CDC MMc?s will be 24KV @ up to 15kw DC variable 
> to 500bps. I?ll go run this setup.
>
> Hey its getting late again.
>
> Till that time
> Jim Mora
> Ojai,CA