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[Towertalk] plywood templates

To: <>
Subject: [Towertalk] plywood templates
From: (Richard Karlquist)
Date: Thu, 1 Aug 2002 08:16:11 -0700
I poured two bases for MA-550 poles,
which have 4 bolts, in a square
about 6 inches on a side.
In both cases, the J-bolts migrated
inward about 1/16 to 1/8 of an
inch, despite having them bolted
to a template made from a 2x12.
The bolts were very tight against
the inside of the holes in the
wood.  I attribute this to concrete
shrinkage.  It certainly wasn't due
to "nudging".  I was lucky that there
was enough slop in the base to get
the bolts into the holes anyway.

Rick Karlquist    N6RK 

> -----Original Message-----
> From:
> []On Behalf Of FireBrick
> Sent: Thursday, August 01, 2002 6:40 AM
> To: TowerTalk List
> Subject: [Towertalk] plywood templates
> >From my many years as a licensed contractor in Chicago and 
> helping tower
> installations I've found a common problem.
> When using a piece of plywood as the template for holding 
> the bolts during
> the concrete pour, I've found that people have nudged the 
> bolts slightly out
> of plumb during the actual pouring.
> Even a slight amount of difference between the true 
> vertical plane will
> cause the bolts sticking out of the concrete to not fit the 
> tower base
> plate.
> This will cause difficulties in installing the plate.
> And the longer the bolt length above the plywood, the more 
> the possibility
> of error.
> I've found a way to protect against this.
> Use two pieces of plywood with a 2x4 in between. And then 
> drill your hole
> with a bit that is the same size as the bolt or just a hair larger.
> Use a nut and washer on each side of the plywood and 
> tighten securely.
> I hope you can picture what I'm describing.
> This is a technique we use to set bolts which will hold up 
> steel columns.
> -----------------------------------------------------
> Drugs may lead to nowhere, but at least it's the scenic route.
> -----------------------------------------------------
> Bill H. in Chicagoland
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