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[TowerTalk] Hole Alignments

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Subject: [TowerTalk] Hole Alignments
From: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK)
Date: Mon, 18 May 1998 12:57:43 +0100
James D. Bruce wrote:
>What is the best way to mark and drill holes in a straight line along an
>alumimun tube? Also drilling thru to the other side of the tube straight? An
>example would be 2 holes along the axis of an element for a U-bolt. It seems
>that I never get it correst and end up enlarging the holes to get hardware
>to fit.

The Black& Decker tool looks like an interesting alternative to V-
blocks, although it still needs a drill press to get accurate alignment
of a row of holes along the boom.

One way to solve that problem is to mount a spirit level crosswise on
the boom - for example, tape the level to the first element mounting
bracket. The idea came from Hints & Kinks (QST) a few years ago.

The ultimate solution is a square-section boom. This is certainly a good
option for VHF yagis, where the drill tends to bend and skid off the top
of a small-diameter round boom. A rigid "center drill" makes it easier
to start a hole on a curved surface, but those drills usually aren't
long enough to go right through to the opposite side.
 
73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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