[TowerTalk] U-bolts for holes with 1 and 7/8 centers

[Rick Karlquist]

Many catalogs will sell 2 1/2 inch U bolts as intended for
"2 inch pipe" which is 2 3/8 OD.  The idea of that the U
bolt supports the weight of the pipe.  NOT that the U bolt
prevents the pipe from rotating.  Why would a plumber
care about that?  For antenna work, you
want it to "fit like a glove".  Even if a U-bolt is listed
as 2 3/8 inside width (never seen one of those), they
are not precision items and would need tweaking if you
want a tight grip on a 2 inch water pipe.  Also keep in
mind that galvanized 2 inch masts are larger than 2 inches.
I like to enlarge the holes that the U bolt goes into so
that I can focus on fitting the tubing properly and let
the ends go where they may.

Rick N6RK

john at kk9a.com wrote:
> I have resized many u-bolts without issue and it is quite easy as Gerald
> said.  Once I had a difficult size to find and I located it in a SS
> muffler
> clamp which I purchased from Summit Racing (CEO is NO8D).
>
> John KK9A
>
>
>
>
> To: w3qx at qsl.net, towertalk at contesting.com
> Subject: Re: [TowerTalk] U-bolts for holes with 1 and 7/8 centers
> From: TexasRF at aol.com
> Date: Mon, 13 Jun 2011 06:37:09 EDT
> List-post: <towertalk at contesting.com">mailto:towertalk at contesting.com>
>
> William, I recently had a similar problem; needing some ubolts for 2  3/8"
> outside diameter pipe.
>
> No standard sizes were available. The next smaller size was expanded to
> fit
>  by whaming the center of the ubolt with a hammer. This caused the legs to
> spread  apart and no longer parallel. The legs were reformed to correct
> geometry by  placing them over a smaller piece of scrap pipe and squeezing
> them
> together in a  vice.
>
> It actually took less time than writing about it here. And best of  all,
> they fit just fine.
>
> Your 70cm yagi was designed to fit a 1 5/8" support mast. Many, if not
> most, cross yagis are used with a Yaesu or Kenpro elevation rotator. Both
> theses rotators are made to accept a 1 5/8" through boom.
>
> I will check my ubolt collection later today; I had some stainless steel 1
> 5/8" size at one time, may still have some.
>
> 73,
> Gerald K5GW
>
>
>
>
>
>
> In a message dated 6/12/2011 11:32:39 P.M. Central Daylight Time,
> w3qx at qsl.net writes:
>
>
> All
>
> An otherwise very good 70cm yagi has a boom and  clamp plate with
> pre-drilled quarter-inch holes:  their _centers_ are  1 and 7/8 inches
> apart.  The correct u-bolt was missing.
>
> Don't  ask how how many places (including McMaster) and how long I've
> looked for  a u-bolt with centers of its [ends] 1 and 7/8 inches
> apart.  I've  learned there are about a half-dozen common u-bolt
> sizes, and for that  dimension none come close.
>
> Help will be appreciated.  Bolt stock  section 3/16 inch should be
> good; 1/4 inch would be very  tight.
>
> Best regards,
> William W3QX
>
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