You mean it's supposed to be straight AND true? I've always taken the "That
looks arbout right" approach. OK, maybe not as the sole means of determining
it's straight and true, but I don't go much beyond the spirit level.
I use a spirit level on the legs of the bottom two of three sections. From
there on up I just sight from three different locations to make sure it's
straight. IE the mark I eyeball with a vertical line although if I have a
transit handy I'll use one. So far I've only used the transit to check and
it was within an inch or so. I have an older "rotating" laser transit, but
getting that true is as much an art as it is technology. I have two of the
small self leveling lasers and I've not been able to get one of those to
match the manually leveled laser transit which is advertised a 1/4 inch in
100 feet, but it'll do better. When tested against a known line the small
self leveling ones "That I have" have never come close to that even though
they advertise such.
When checking a tower for vertical and straight with a laser level or
transit you have to be very careful about where that thing is pointed. They
are *bright* and can at least temporatirly blind some one from quite a
distance. We live on the edge of a subdivision and I'd have to install
"blinds", or some form of light blocking so the beam could not hit a house
or any where out in the woods. That still leaves the air and a plane could
easily fly though the beam a mile or so out. It might not cause flash
blindness but it can leave one whale of an after image at even one to two
miles. Due to recent incidents that'd probably result in a yard full of
black SUVs and the feds knocking at the door.
As far as using a plumb bob. I have one of solid brass and a screw in
carbide tip for another project. It's heavy, but it's the wind on the string
that causes it to move around. The water pail mentioned earlier is a good
idea for dampening the movement but it will not prevent it or even reduce
it. It will only slow the back and fourth movement. IOW it's a damper not an
eliminator. OTOH it can eliminate *some* oscillations.
Being long on innovation as a result of being very short on ambition I
almost always take the easy way out. That is with the exception of building
a 100 foot tall 45-G by hand. That was more to being cheap...er... economy
minded, winning out over lack of ambition. Even then I did a lot of
planning to save on effort.
BTW I have found "for me" looking up the legs of the tower is almost useless
to determine if the tower is straight as they all look bent on every leg.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
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