Center Drills can be purchased in 6 inch lengths. I use them
at work all the time.
Art
KB7WW
Ian White, G3SEK wrote:
> 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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