Hi All, here is a bit of clarification on the Big Grip and thimble size
issues:
Rohn does not make Big Grips; Preformed Line Products Co. makes them and
sells them to Rohn. 1/4" EHS uses a BG2144. All BG2144 grips are the same
design
whether purchased through Rohn/Radian or other distributors, such as Texas
Towers. There are other grips made for utility use that fit 1/4" EHS but they
are shorter, have fewer strands and not recommended for tower guy
applications. These other grips will not be identified as Big Grips.
For the 1/4" Big Grip, BG2144, Preformed Products calls for a 1/2" thimble
and Rohn/Radian calls for a 3/8" heavy thimble. The groove in these two sizes
have the same dimension so it makes sense that either a 1/2" regular thimble
or a 3/8" heavy thimble will work fine. Texas Towers carries the heavy series
because this is the size recommended by Rohn/Radian.
A 3/8" heavy thimble is a very close fit into the eye of a 1/2" X 12
turnbuckle. Once the legs are twisted apart, it takes only a slight
"persuasion" to
push the thimble through the eye of the turnbuckle. If this seems like too
much effort then by all means a 1/2" shackle can be used to connect the thimble
and turnbuckle. Texas Towers has these shackles in stock as they are required
when connecting Phillystran grips/thimbles to turnbuckles and other
hardware.
Joining Phillystran to EHS can be done by back to back thimbles or with
shackles.
73,
Gerald Williamson
General Manager/Texas Towers
In a message dated 8/31/2006 6:22:47 A.M. Central Daylight Time,
donovanf@starpower.net writes:
Hi Dick,
It seems unlikely that Rohn makes preformed Big Grips.
Preformed specifies use 1/2 inch heavy duty thimbles. The cost isn't much
higher than 3/8 inch heavy duty thimbles. The only way to resolve this is to
communicate directly with engineers at the companies involved...
You would probably regret fastening Big Grips (and thimbles...) to the guy
attachments without use of shackles. As you point out, it would be
inconvenient to remove the guys.
3/8 inch shackles are an ideal match to the load capacity of 1/4 inch EHS
guy wire (5/16 inch shackles have a breaking load capacity of 6600 pounds,
slightly less than the breaking load capacity 1/4 inch EHS). In my previous
e-mail I recommended that you use 7/16 inch shackles; however, their 13,300
pound breaking load capacity in unnecessarily large for your guy system.
Good luck with your new tower installation Dick!
73!
Frank
W3LPL
---- Original message ----
>Date: Thu, 31 Aug 2006 03:19:45 -0400
>From: "Dick Green WC1M" <wc1m@msn.com>
>Subject: Re: [TowerTalk] Rohn 55 thimbles and turnbuckles
>To: <donovanf@starpower.net>, <towertalk@contesting.com>
>
>Frank,
>
>Glad you weighed in on this.
>
>I got 1/2" thimbles for the Preformed Grips I'm using with the 6700 lb
>Phillystran -- as specified on the Texas Towers website. So far, so good.
>
>But I ordered 3/8" heavy-duty thimbles for the 1/4" EHS bottom leaders
>because that's what Rohn specifies for use with their 1/4" EHS Big Grips
>(part # BG2144.) Here's a link to the parts list in the Rohn catalog:
>
>http://www.antennasystems.com/PDFs/ROHN/55G/55G-14.pdf
>
>I'm using 6700 lb Phillystran with 1/4" EHS leaders on all three guys,
which
>isn't quite up to the 110 MPH spec (the top guy is supposed to be 5/16"),
>but exceeds the 90 MPH spec. The parts list shows BG2144 grips and 3/8"
>thimbles for the 1/4" EHS. Is there a difference between Rohn Big Grips and
>Preformed Big Grips?
>
>Do you think the Rohn-specified 3/8" thimbles are OK for their 1/4" EHS
>grips? If so, would you still use a 7/16" shackle, or something smaller?
>What's a good source for high-quality shackles? Would you recommend using
>shackles to connect the 1/2" thimbles at the end of the Phillistran grips to
>the solid links on the GA55GD guy brackets? Here's a diagram of the
bracket:
>
>http://www.antennasystems.com/PDFs/ROHN/hardware_accessories/HA-79.pdf
>
>The 1/2" thimble should fit inside the loop OK, but a shackle would make
>installation and removal easier.
>
>73, Dick WC1M
>
>-----Original Message-----
>From: donovanf@starpower.net [mailto:donovanf@starpower.net]
>Sent: Wednesday, August 30, 2006 9:00 PM
>To: towertalk@contesting.com
>Subject: Re: [TowerTalk] Rohn 55 thimbles and turnbuckles
>
>Dick,
>
>1/2" heavy duty thimbles are required by Preformed Line Products for use
>with their Big Grips for 1/4" guy wire and Phillystran.
>
>See:
>http://www.preformed.com/artsfest/files/AppProc/SP2049-3.pdf
>http://www.preformed.com/artsfest/files/AppProc/SP2806.pdf
>
>Use a 7/16" shackle to make the transition from the thimble to the
>turnbuckle.
>
>73!
>Frank
>W3LPL
>
>---- Original message ----
>>Date: Wed, 30 Aug 2006 19:47:29 -0400
>>From: "Dick Green WC1M" <wc1m@msn.com>
>>Subject: [TowerTalk] Rohn 55 thimbles and turnbuckles
>>To: "Tower" <towertalk@contesting.com>
>>
>>Reviewing the Rohn parts list for a 110â 55G tower @90-100MPH, I
>>decided to go with Ââ EHS for all three levels (actually, 6700lb
>Phillystran with Ââ
>>EHS leaders. Following the parts list, I ordered 3/8â heavy-duty
>>thimbles
>>(3/8THH) and Ââx12â eye-jaw turnbuckles (1/2TBE&J). Rohn specifies that
>>the thimble should be one size larger than the guy diameter. The parts
>>have arrived, and Iâm perplexed to find that the 3/8â thimbles donât
>>fit inside the eye part of the turnbuckles. I might be able to make
>>them fit by flattening the edges of the thimble a bit (sandwiching it
>>between a piece of two pieces of flat steel and hammering the flare out
>>of the edges), but before I try that, Iâd like opinions on this. I
>>canât be the first person who has run into this. It looks like a
>>shackle would work, but Rohn doesnât specify them for 55G towers. Comments?
>>
>>
>>
>>73, Dick WC1M
>>
>>
>>
>>_______________________________________________
>>
>>
>>
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