[TowerTalk] LM470 base dimensions

[K0DAN]

I don't think you will (or should) need washers with the base. If the legs
of the Tilt Assembly and tower are installed per specs there will be a
little clearance between them, which you will need when you hoist the tower
to vertical. When you put the bolts (5/leg?) in, they will pull the steel
together and you will have no need for washers, altho if you have room for
lockwashers, plus a couple stainless washers if you want to bond copper
grounding to galvanized.

In fact, when you're tilting the tower from horizontal to vertical,
sometimes the alignments will not be as good as you planned or hoped for,
and you will need to use a big pry bar (I use a truck tire iron), drift pin,
etc., and bring the legs & bolt holes into alignment by inserting &
tightening one bolt at a time. I think that washers will just be another
obstacle and complication. IIRC the towers I have been involved with have
less than 1/4" spacing but I think with proper bolt installation they will
pull together,.

I assume you have the current manual from BAMA? While things have changed a
bit from the older to newer towers, the basics are essentially unchanged.

There are drawings of the footings which show the rebar cage, tower, etc., 
these should give you the construction details you need.

GL es 73

dan
k0dan



-----Original Message----- 
From: Roger (K8RI) on TT
Sent: October 19, 2013 19:30
To: towertalk at contesting.com
Subject: [TowerTalk] LM470 base dimensions


I'm getting ready to do the final welds on the base.  Unfortunatel there
are no specific dimensions given in the paperwork.

The outside distance on the tower "ears" is 23".  I'm using the raising
fixture to hold the base "ears" for building the rebar cage.  When
bolted to the raising fixture the "inside" dimension between the ears is
23 1/4" That leaves an 1/8th of an inch space between the tower ears and
the base ears on each side , or 1/4" total.

I'm assuming I should space the base ears in from the raising fixture
with washers, to give no more than 1/32nd of an inch clearance so when
the bolts are tight the tower and base ears will mate flush and tight..
This should allow for a snug fit, but not interfere with raising the
tower and give face to face contact for a good holding force when the
bolts are tight ( snug plus 1/2 turn)

Comments?

73

Roger (K8RI)

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