In addition to blowing out the dust, a good steel or brass brush should
be used to clean the compacted dust from the barrel of the hole after
drilling.
Blow out the hole, brush vigorously, blow out, repeat.
Rotary hammer drill bits are available up to 36" long, longer than any
likely need for an anchor. There is a bit with a tip designed for going
thru rebar as well as concrete. $66 for a 1.125 x 17" depth capacity.
http://www.coastaltool.com/bosch/hammer_bits_spline.htm
Most rental shops will rent the hammer drill but only sell the bits, for
obvious reasons.
Grant KZ1W
On 2/9/2011 8:57 AM, K7LXC@aol.com wrote:
>
> In a message dated 2/8/2011 5:58:35 P.M. Pacific Standard Time,
> towertalk-request@contesting.com writes:
>
>> I will be upgrading my tower and will be using my existing base. This
> will
> require drilling the existing concrete base and epoxing in some new bolts.
> I would be interested in exchanging some emails with someone who has done
> this.
>
>
> This is covered in my UP THE TOWER book (available from
> _www.championradio.com_ (http://www.championradio.com) ). As is a picture
> of the XE2DV
> super station on the Sea Of Cortez.
>
> In short (assuming the existing base is big enough for the new tower),
> rent an impact hammer and an appropriate sized diamond drill bit (for
> cutting any possible rebar) and drill where the new holes go.
>
> Blow the dust out of the holes (a big straw or can of compressed air
> work FB), use contractor's epoxy in the hole, wait for it to cure and you'll
> be good to go. You'll need a special 2-barreled gun for the 2-barreled
> epoxy cartridges. You can probably rent all of these at your local rental
> store.
>
> Contractors do this every day and the epoxy is stronger than the
> concrete so no worries about strength.
>
> Cheers& GL,
> Steve K7LXC
> TOWER TECH
> and
> Champion Radio Products
>
>
>
>
> _______________________________________________
>
>
>
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>
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