[TowerTalk] Mast bending

[Lee Wells]

Hey guys....I'm getting ready to put the antennas on the mast
of my new tower and noticed that the mast seems to have
a lot of "give" or a "springy" feel.  The mast is a little
over 23 feet long.  I've got about 4 feet out the top
of the tower, thrust blocks at the top of the tower and down
3 feet, then the mast goes through the rotor plate (8 ft
down from the tower top).  So I've got about 11 feet hanging
below the rotor plate and if I push on the bottom, I can
move the mast 4-5 inches off center.

I used MARC to determine that I needed a mast with 50,000
psi and .188" wall.  When I orderd the steel tubing 
I went on up to .25" wall, and the tubing is supposed to
have a yield strength of 58,000 psi.

I'm definetly going to check with the supplier on Monday
to verify the specs of the tubing.

What I want to know from Towertalkians is how much
play or spring should I expect?????   Is this normal?
This is my first tower so I simply don't know
what to expect on this.  

I was hoping to get everything finished this weekend,
but I want to double check on this before I
mount the first antenna and run the mast the rest
of the way up.

Thanks & 73's
--Lee


---
Lee Wells - KT4ZX
leewells@lexmark.com
Georgetown, KY

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