[TowerTalk] Rohn 45 Tower Bolts Torque Setting

[Mark Robinson]

The thing was that on Rohn 25 you get nowhere near the limits of the bolt 
before the tubing of the tower starts to crush. A small amount of crush is 
required without causing the tower leg to become permanently oval. I have 
seen legs badly crushed by over zealous tightening.

 The legs on the Rohn 45 are much thicker and can take a lot more before the 
leg starts to crush. I guess there are no published Rohn guide lines. It may 
be more important with a non guyed 25 or 45 where slop in the tower will 
eventually cause the bolt holes to become oval. This is probably not going 
to happen with a guyed tower which has a strong downward force exerted by 
the guy wires.


Mark N1UK

----- Original Message ----- 
From: <hanslg at aol.com>
To: <towertalk at contesting.com>
Sent: Friday, 30 April, 2010 3:13 PM
Subject: Re: [TowerTalk] Rohn 45 Tower Bolts Torque Setting


>
> Yes, I would also worry about the stretch of my tower bolts if my tower 
> was jumping up and down 6500 times a minute.
>
> If you want to be that precise you have to worry about the exact hardening 
> of the bolt as that will affect the force-stretch curve. The exact 
> diameter also comes in as a factor too. Huu!
>
> Again, the only time I know about a need to know the force a bolt was 
> applying was when the friction between the two fastened pieces were 
> important (which is not the case with our towers, at least not mine). That 
> also required an established routing to prepare the two friction surfaces. 
> (I only seen this once and believe it was not used much due to the rather 
> complicated procedure and possibilities for errors.)
>
> Anything more?
>
> Hans - N2JFS
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Robert Chudek - K0RC <k0rc at citlink.net>
> To: towertalk at contesting.com
> Sent: Fri, Apr 30, 2010 1:04 pm
> Subject: Re: [TowerTalk] Rohn 45 Tower Bolts Torque Setting
>
>
> There is an interesting article about this, here: 
> http://www.carcraft.com/techarticles/116_0609_using_rod_bolt_stretch_tool/index.html
>
> I'll have to check my tower bolts to see if they have the "dimples" on 
> both ends
> for centering the gauge.
>
> 73 de Bob - KØRC in MN
>
>
>
>
> Message: 1
> Date: Thu, 29 Apr 2010 13:39:27 -0700 (PDT)
> From: Steven Kerns <n3fti at yahoo.com>
> Subject: Re: [TowerTalk] Rohn 45 Tower Bolts Torque Setting
> To: towertalk at contesting.com
> Message-ID: <430261.84761.qm at web43135.mail.sp1.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Mark,
>
> Using torque measurement is not accurate because of friction related to
> different surface tensions of the fasteners and the difference in 
> lubricants.
>
> To get an an accurate measurement you should read the bolt stretch with a 
> dial
> indicator using a bolt stretch gauge.  One can be purchased here:
> http://www.summitracing.com/parts/ARP-100-9942/  ;-)
>
> Steve, N3FTI
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