[TowerTalk] [Bulk] Re: tower insulators

[Roger (K8RI) on TT]

On 9/3/2014 1:30 AM, Roger (K8RI) on TT wrote:
> On 9/2/2014 8:58 PM, john at kk9a.com wrote:

I forgot to say, we often use a synthetic cloth over the last lay up, 
called "Peel Ply".  After the last lay up cures, you simply peel the 
cloth off and it's ready for the next layer.Also, wiping down a piece 
that didn't have peel ply used, with Acetone will make it a bit sticky 
and the next layer will adhere much better. IIRC that is explained in 
the text.

http://www.rogerhalstead.com/G3_files/GIII_Diary.htm shows the use of 
peel ply and types of cloth and coarseness of the weave that can be 
used. Fine is good, but you reach a point where the cloth becomes too 
fragile to easily and completely remove. It also helps to  "wick off" 
excess resin requiring less skill and waste.

This is much cheaper than purchasing cloth labeled "Peel Ply"!

73

Roger (K8RI)

>
> 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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