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Rohn bolts

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Subject: Rohn bolts
From: (george fremin iii)
Date: Tue, 17 Dec 1996 18:27:46 -0600 (CST)
>       A question:  Does anyone have a theory as to why Rohn uses fine
> thread on tower bolts?
>Regarding the use of fine threads, they allow a much better application of
>torque to the fastener. The finer threads are much like gear reduction,
>providing more mechanical advantage and a smoother tensioning. I would think
>that on a tower, this would allow a more uniform tensioning and possibly
>lower likelyhood of the nuts working loose. Other thoughts?

I was going to stay out of this round of the "bolt thread" but
I will once again pass on the best thing that I learned from
this topic last year.  

If you really want to know about nuts and bolts and fasteners
do what Dave W6NL(ex.QHS) suggested to me.  

Go buy this book: "Nuts, Bolts, Fasteners and plumbing handbook"
                   by: Carroll Smith; Pub. Motorbooks International
                       ISBN 0-87938-406-9

This book has all the answers - plus it is very well written.

On the above question Carroll Smith says,

"Speed of assembly is the major reason that so many automotive and
 industrial fasteners feature coarse threads.  Strength and weight
 are the reasons that almost all aerospace fasteners feature fine 
 threads. Except when I am threading into a casting, I do not use 
 coarse threaded fasteners."


"When the female thread will be weaker than the male thread, use a
 coarse thread pitch.  The reason is that the samller the minor 
 diameter of a female threaded part, the greater will be the thread
 area, the stronger will be the static strenght and the higher will
 be the fatigue limit of the part.  Conversely, the larger the minor
 diameter of the male threaded part, the greater will be the stress 
 area adnt he stronger and more fatigue resistant the bolt or stud
 will be."

p. 39 --

Get the book it is COOL.


George Fremin III
Austin, Texas C.K.U.     "Where is the line noise?" -Trey N5KO

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