[TowerTalk] [Bulk] Re: tower insulators

[Roger (K8RI) on TT]

On 9/2/2014 8:58 PM, john at kk9a.com wrote:

Fiberglass  "lay ups" come in a wide variety of strengths, or it is 
probably more accurate to say the strength of fiberglass components 
varies widely,

It depends on the density of the weave, the angle of the weave to the 
axis of the component.  A dense weave with Vinyl-ester resin of a low 
viscosity like Dow Derakine (sp?). Multi layers with alternating weave 
at 45 degrees and linear is extremely strong.  The cloth for each layer 
is saturated with resin, laid up, and then the excess resin is squeegeed 
out just to the point where the cloth is not dry.  You can use a lot of 
cloth and resin learning how to make flat layups, and then complex 
shapes without wrinkles.  That and this resin can have a mixed working 
life of 10 to 15 minutes.  That doesn't give you much time to make 
individual layups.

http://www.rogerhalstead.com/G3_files/GIII_Diary.htm The 8th photo from 
the top shows making a complex shape out of a dense cloth on the 45 deg 
bias with no wrinkles.

60 feet is well beyond the rating for 25G with no antennas. However, the 
fiberglass is probably much stronger by several times than the 25G which 
gets its strength from the shape.

73,

Roger (K8RI)

> Your fiberglass inserts were amazingly strong to hold up 60' of freestanding
> Rohn 25g! I would not try that using a standard base. Are there different
> strengths of fiberglass material?
>
> John KK9A
>
> To:	"w2ttt at att.net" <w2ttt at att.net>
> Subject:	Re: [TowerTalk] [Bulk] Re: tower insulators
> From:	Stan Stockton <wa5rtg at gmail.com>
> Date:	Mon, 1 Sep 2014 23:46:42 -0500
>
> Gordon,
>
> No, sorry for misunderstanding.
>
> Here is what I said regarding the 3/8 rod...
>
> "After seeing the towers bend in about a. 60 mph wind, I used 3/8 fiberglass
>
> rod to guy them to small, homemade anchors - rod welded to a short piece of
> angle.  Each anchor is in about a bag of Quickcrete."
>
> The towers were previously unguyed.  I believe the inside diameter of Rohn
> 25G
> legs are around 1.125 and that is the diameter of the rods that insulate one
>
> section from the other. - of course with holes drilled to accept the normal
> sized bolts.  Then I also have a fiberglass plate that spans the joint,
> attached above and below the splice with galvanized U bolts.
>
> What K8LX understood is correct, and yes, the fiberglass rod I used is very
> strong stuff. I got it from a company that makes those long rods with
> galvanized fittings on either end for the utility companies - the ones that
> are
> rated for about 20,000 pounds in a straight pull.  The fiberglass rod was
> 1-1/4" diameter and I had it turned down on each end of maybe 12 inch long
> pieces
>
> The towers are guyed at about the 25 foot level with the 1.125" rod in the
> legs
> and the 3/8 fiberglass rod for guy wires and the fiberglass plates that span
>
> the joints.  I am not a bit worried about the 35 feet above the guys, given
> that the towers survived some big winds over about 8 years with no guy wires
> at
> all.
>
> I looked, and there is a photo under low band antennas at k5go.com
>
> 73...Stan, K5GO
>
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>
>
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-- 

73

Roger (K8RI)


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