[TowerTalk] Rohn 55 thimbles and turnbuckles

TexasRF at aol.com TexasRF at aol.com
Sat Sep 2 10:50:21 EDT 2006 

 
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 at 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 at msn.com>  
>Subject: Re: [TowerTalk] Rohn 55  thimbles and turnbuckles  
>To: <donovanf at starpower.net>,  <towertalk at 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 at starpower.net [mailto:donovanf at starpower.net] 
>Sent:  Wednesday, August 30, 2006 9:00 PM
>To:  towertalk at 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 at msn.com>
>>Subject: [TowerTalk] Rohn 55 thimbles and  turnbuckles
>>To: "Tower"  <towertalk at contesting.com>
>>
>>Reviewing the Rohn  parts list for a 110’ 55G tower @90-100MPH, I 
>>decided to go with  ¼” EHS for all three levels (actually, 6700lb
>Phillystran with  ¼”
>>EHS leaders. Following the parts list, I ordered 3/8” heavy-duty  
>>thimbles
>>(3/8THH) and ½”x12” 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 I’m  perplexed to find that the 3/8” thimbles don’t 
>>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, I’d like opinions on this. I  
>>can’t be the first person who has run into this. It looks like a  
>>shackle would work, but Rohn doesn’t specify them for 55G towers.  Comments?
>>
>> 
>>
>>73, Dick  WC1M
>>
>>  
>>
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>>
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