[TowerTalk] Rohn 55 thimbles and turnbuckles

[donovanf at starpower.net]

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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