I'm not so sure nominal thimble size tells the whole story.
While Preformed specifies a 1/2" thimble for 1/4" EHS cable, note that the
minimum groove diameter for a Preformed grip used with 1/4" EHS cable is
5/16". Rohn, on the other hand, specifies their 3/8THH thimble for their
BG144 Big Grips used with 1/4" EHS cable. Rohn's heavy duty 3/8" thimble has
a rather large groove diameter. It's dark now so I can't go out and measure
mine, but I'm pretty sure the groove diameter is at least 3/8" if not
larger. It's certainly larger than 5/16" and much larger than a standard
3/8" thimble you would get in a hardware store. I'm sure it's large enough
to meet the Preformed spec, so it's not necessary to use Rohn's 1/2THH
thimbles (and it's not required by Rohn's specifications.)
Being a good little boy, I followed the Rohn spec and used their 3/8THH
thimbles with BG144 Big Grips for my 1/4" EHS leaders. Despite not using the
size recommended by Preformed, it certainly did not appear that the groove
was too small for the grip. A bonus was that the gap between the ends of the
thimble was plenty large enough to slip over the 1/2" thimbles I used with
Preformed grips for the 6700 lb Phillystran guys (as recommended and sold by
Texas Towers.) Strictly speaking, the minimum groove diameter for Preformed
grips for that size Phillystran is 7/16", but I would assume heavy duty 1/2"
thimbles are more readily available and can be used for the two larger sizes
of Phillystran carried by Texas Towers.
Anyway, it was not necessary to modify the Rohn 3/8THH thimbles by spreading
the legs in a vice. Does anyone know if Rohn deliberately has their heavy
duty thimbles made with the ends spread wider than standard thimbles?
73, Dick WC1M
> -----Original Message-----
> From: donovanf@starpower.net [mailto:donovanf@starpower.net]
> Sent: Friday, April 13, 2007 10:53 AM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Fwd: Re: Guy wire assembly question
>
> Phil,
>
> I've also used the bench vise method for years.
>
> Many tower installations do not use the Preformed Line Products's
> recommended thimble size for big grips. For 1/4 inch EHS, PLP
> specifies
> 1/2 inch heavy duty thimbles. Here are the applicable PLP documents:
>
> http://www.preformed.com/artsfest/files/AppProc/SP2049-3.pdf
>
> http://www.preformed.com/artsfest/files/AppProc/SP2806.pdf
>
> Good luck!
>
> 73
> Frank
> W3LPL
>
>
> ---- Original message ----
> >Date: Fri, 13 Apr 2007 09:38:16 -0500
> >From: "Keith Dutson" <kdutson@sbcglobal.net>
> >Subject: Re: [TowerTalk] Guy wire assembly question
> >To: <towertalk@contesting.com>
> >
> >This (bench vise and Crescent wrench) is the way I do it. Have the
> >turnbuckle handy to put on the thimble and the Crescent wrench can
> then be
> >reversed to close the thimble while still clamped into the vise.
> >
> >73, Keith NM5G
> >
> >-----Original Message-----
> >From: towertalk-bounces@contesting.com
> >[mailto:towertalk-bounces@contesting.com] On Behalf Of Dubovsky,
> George
> >Sent: Friday, April 13, 2007 9:32 AM
> >To: bob finger; Phil Jung
> >Cc: towertalk@contesting.com
> >Subject: Re: [TowerTalk] Guy wire assembly question
> >
> >Well, that's one way to open up a thimble, but a little too
> Neanderthal for
> >my tastes ;-)
> >
> >I usually capture one half of the thimble in a vise, with the long
> dimension
> >horizontal, and the thimble opening just above the top of the vise
> jaws,
> >sort of like the letter "C". I grab the free side of the thimble (the
> top of
> >the "C") with a big Crescent wrench and lever it sideways to the plane
> of
> >the thimble, and that opens it up. In the field, I close them back up
> with a
> >pair of adjustable wrenches. The galvanizing doesn't seem to be
> damaged when
> >you do it this way.
> >
> >73,
> >
> >geo - n4ua
> >
> >
> >>In method one above you need to pry open one of the thimbles. A big
> >>hammer and big chisel are the easiest way, then use
> >the
> >> hammer to close it up again. Then use the big grip to connect the
> >EHS.
> >> 73 bob de w9ge
> >
> >----------------------------------------------------------------------
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> >--------------------
> >[mf2]
> >
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