Rich,
Without arguing, I'm most sure the deflection was caused by 'nudging.
It's most visible as being nudge inwards.
As try as you may, you can not dump concrete into the hole without moving
the bolts unless they are cage welded as Steve suggests or extremely secured
at the top.
The thicker the template, the more parallel plumb the bolt tops will be.
Concrete does shrink, slightly, but not in that way.
----- Original Message -----
From: "Richard Karlquist" <richard@karlquist.com>
To: "FireBrick" <w9ol@billnjudy.com>; "TowerTalk List"
<towertalk@contesting.com>
Sent: Thursday, August 01, 2002 10:16 AM
Subject: RE: [Towertalk] plywood templates
> 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
> richard@karlquist.com
> www.n6rk.com
> www.karlquist.com
>
> > -----Original Message-----
> > From: towertalk-admin@contesting.com
> > [mailto:towertalk-admin@contesting.com]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
> > w9ol@billnjudy.com
> > www.billnjudy.com
> > http://files.billnjudy.com
> >
> >
> >
> > _______________________________________________
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