On 7/29/2010 1:31 PM, David Gilbert wrote:
> I'm kind of confused about all this discussion involving the use of a
> plumb bob, which I think would be impractical in most environments.
>
It is.
> It seems to me that there are two considerations at hand:
>
> 1. Trying to make the tower straight
> 2. Trying to make the tower vertical.
>
>
Those go hand in hand.
> An easy guide for first objective can be accomplished by fastening a
> string (or rope for better visibility from the ground) to the top and
> bottom of the tower (spaced a few inches from the tower) and stretching
> it taught. It isn't even necessary to measure the distance from the
> tower to the line ... you just stand to the side and look for parallelism.
>
>
It's easier to do down the center, or at least I find it so.
> Making a straight tower vertical would only require the help of a good
> level applied to the bottom section.
>
Depends on the accuracy of the level.
Theodolite is probably the most accurate if you can find one to rent.
> Why would that not be sufficient?
>
>
The leg needs to be really straight and the user very careful with the
level. A fraction of a bubble in 3 or 4 feet can make quite a difference
over a 100 feet.
73
Roger (K8RI)
> 73,
> Dave AB7E
>
> p.s. It is possible to make the guideline taut as a guitar string by
> doubling it and using a lever (piece of wood) to twist the pair.
>
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