[TowerTalk] LM470 base dimensions

[Roger (K8RI) on TT]

On 10/20/2013 12:49 AM, K0DAN wrote:
> I don't think you will (or should) need washers with the base.

I was referring to between the base ears and the raising fixture.

> 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,

I have drift pins and a railroad pry bar, although a man needs to be in 
pretty good shape to use a pry bar that size.  I used it to move a one 
ton Bridgeport milling machine the length of the shop, but I had two 
working arms then. <:-))

> 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,.

If the base is properly positioned for mating with the tower base then I 
will need spacers between the base and raising fixture which doesn't 
have near the stress even when tilting the tower with a good sized 
tribander as dopes the tower to base..

>
> 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.
>

I have the original manual as well as the current digital manual from 
the manufacturer.

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

The manuals do not give the dimensions of the ear to ear spacings. They 
show the rebar cage dimensions, but not the main leg placement.  You are 
left to infer several dimensions and clearances.  They show where they 
go, but not the dimensions.  They give the placement of the #3 and #5 
rebar, but that can be just as good with a "that looks about right"  
Placement of the rebar can vary 3 or 4 inches with no problem.  It's 
only duty is to hold the concrete together which is why it's wired 
together instead of being welded.

73

Roger (K8RI)

>
> 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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