[TowerTalk] Why preload guy lines?

[K7LXC@aol.com]

In a message dated 8/8/2005 5:25:06 AM Pacific Daylight Time, 
towertalk-request at contesting.com writes:

>  Right, it's a measure of the force required to bend a wire
under a particular tension.

> So there are two components of the 'resistance': that caused
by the tension, and that caused by the wire stiffness.

> The wire stiffness remains constant. At low tensions, it
dominates. As the tension increases, becomes a smaller and
smaller percentage of the total. The question is what
percentage of the total at common (10%) pre-tensions?

> I don't own the Loos gauge, but gather that:

> 1) The supplied chart or table does not give alternate
calibrations for different guy material.

> 2) The chart is calibrated for flexible cable (wire rope).

> The larger gages I own have alternate calibrations, but
only for the overlapping guy size range (1/2" to 3/4")
where EHS is available in both 1x7 and 1x19 configurations.

> I would think it might be useful for someone to actually
calibrate the Loos for 3/16" EHS at 400 lbs, and 1/4" EHS
at 600 lbs, and take away any doubt. I may pick one up
from Champion and do it. I should have one of these in my
kit anyway.

    As an unscientific test some years ago, I took several different 3/16" 
guy materials - EHS, Phillystran, and good old 7x19 wire rope - and hooked them 
all together in one length. Then I put the whole thing under 400 pounds 
tension per a Dillon tensionometer and measured each segment. Guess what? They all 
measured 400 pounds on the Loos. And the accuracy vis-a-vis the Dillon was 
within a couple of percent - highly accurate in my book. 

    And like Bud, W2RU, said, having them equalized - regardless of the 
tension - is half the battle.

Cheers,
Steve   K7LXC
TOWER TECH -
Professional tower services for commercial and amateur
Cell: 206-890-4188