[TowerTalk] AB-105 assembly: bolt tightening procedure

[Eric Scace K3NA]

   W3LPL taught me how to build AB-105 and I've constructed a few using the
'piece at a time' method.  It works fine.  Two additional suggestions

   When building a piece at a time, we do not tighten down the bolts right
away.  Rather, we build up as much as 20 feet (two sections) with finger
tight hardware.  ("Finger tight" here means the lockwashers are engaged but
not smashed down into their final position.)  Then we go down to the lower
loose section and tighten each bolt up to the final tightness, starting from
the bottom and working up.  This process makes it easier to align the bolt
holes as pieces are being assembled, and helps ensure the tower is straight
when the bolts are tightened.

   A second tip is to tighten each horizontal level of bolts consistently.
For example, tighten the lowest row of bolts starting with a particular
leg... going around the tower to each bolt at that level in turn... in a
clockwise direction.  Then, move up to the next row of bolts (about 14
inches higher on the tower).  Tighten each bolt at this level, in turn, but
going from bolt to bolt in the OPPOSITE direction (counter clockwise in this
example).

   If you always tighten bolts going around in the same direction, you can
build in a slight corkscrew in a 100 foot tower.  Switching directions
eliminates the corkscrew.

-- Eric R3/K3NA

-----Original Message-----
From: owner-towertalk@contesting.com
[mailto:owner-towertalk@contesting.com]On Behalf Of K7LXC@aol.com
Sent: 2000 July 26 Wed 09:17
To: nj4f@erols.com; towertalk@contesting.com
Subject: Re: [TowerTalk] AB-105 assembly



In a message dated 07/24/2000 10:30:54 AM Pacific Daylight Time,
nj4f@erols.com writes:

> If you pre-assemble it on the laying on the ground, as a complete tower,
>  unless the ground is perfectly level, the tower will by crooked when it
is
>  raised by crane.

    If you're going to build it one-piece-at-a-time the only section that
you
*really* need to have level/plumb is the bottom section and everything will
be FB. This is actually not a bad way to do it. You need two guys on the
tower and it goes relatively fast. I prefer this method since you have to
assemble the sections at some point anyway and this way you avoid the 20-30
minutes per section for plumbing as well as the crane or ginpole time and
cost.

    If you want to build it on the ground, you'll need a flat, level surface
like a driveway. You need to drop a plumb line down through the tower; I use
some string with a wrench or other heavy weight on the end. (A "T" made from
thin pieces of wood that will sit on top of the legs with the string
attached
to the middle makes it easy to use and then remove. A step ladder is
required.) You sight through the tower face, through the string to the edge
of the opposite leg. Have your helper hold the legs in place while you
slightly tighten the nuts. When you've got that pretty well done, then go
back and tighten everything. It'll take you 20-30 minutes per section to do
this. Then you can put several sections together for the crane to pick up.

Cheers,   Steve    K7LXC
Tower Tech

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