The "rib" is pop riveted .. Mark 6dx
----- Original Message -----
From: "Mike Newman" <mnewman@clear.net.nz>
To: <towertalk@contesting.com>
Sent: Friday, September 13, 2002 9:11 PM
Subject: Re: [Towertalk] Tubular Telescopic Masts
> On Wed, 11 Sep 2002 Dino Darling wrote:
> > Send a message to Chip @ k7ja@dxer.com He has 2 on his side yard. If I
> > remember correctly, there is a small piece of channel, welded to the
> length
> > of the inside tube that is "keyed" to a slot in a cap that is welded to
> the
> > top of the outside tube.
> >
> > These masts are NOT water pipe! They are very thin! It amazes me that
> > they even work! These engineers are really smart to get thin metal to
> work
> > the way they do!
> >
> It's the welding of the channel rib onto the water-pipe that bothers
me -I'm
> sure that the pipe will curl from the welding induced stresses. Also
> welding will damage the galvanizing on the water-pipe, and it will cost an
> arm and a leg to re-galvanize the tube after welding.
>
> Water-pipe is thin - 4" medium galv pipe here has a wall thickness of only
> 0.178 ".
>
> I've received some photographs that show a rib screwed to inner extension
> tube, so those tubes must be thicker than normal waterpipe, otherwise
there
> wouldn't be sufficient thread length.
>
> I'll get in touch with Chip.
>
> Mike ZL1BNB
>
>
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