[TowerTalk] Rohn 45 Tower Bolts Torque Setting

[Steven Kerns]

I really don't think we need to worry about precise torquing of tower bolts, let alone bolt stretch.  Seem a little overkill for tower bolts!  Just snug then tight.

I just could not resist throwing in the bolt strech info, I hope everyone realized that I was jesting by my ;-) at the end of the email.

We do use a bolt strech gauge when putting together motors for our blown alcohol dragster.  As Hans noted, ARP (racing bolt mfgr) does give a spec for them to be stretched to depending on material and diameter.

73

Steve, N3FTI





--- On Fri, 4/30/10, Mark Robinson <markrob at mindspring.com> wrote:

> From: Mark Robinson <markrob at mindspring.com>
> Subject: Re: [TowerTalk] Rohn 45 Tower Bolts Torque Setting
> To: towertalk at contesting.com, hanslg at aol.com
> Date: Friday, April 30, 2010, 3:58 PM
> 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
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk at contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk at contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> > 
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>