Hi Wes,
.120" x2 = .240" to .250" it is only .010" clearance (which is 0.25mm !)
That's really tight, in fact I think it is not practical for telescopic
portable use.
.058" x2 = .116" to .125" it is .009" clearance. Even less than previous one.
It seems to me these sizes might be good for permanent use, Yagi elements, etc.
But it seems not usable for field day style mast.
I've been told the "good" clearance for portable telescopic use should be
between .020" and .040".
Thank you for the valuable information Wes.
73, Maximo
<http://foro.ea1ddo.es/>
________________________________
De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Wes
<wes_n7ws@triconet.org>
Enviado: miércoles, 17 de julio de 2019 15:18
Para: towertalk@contesting.com
Asunto: Re: [TowerTalk] Aluminium telescopic mast
Maximo,
The easiest, although expensive, source is
https://www.dxengineering.com/search/department/rigid-tubing?SortBy=Default&SortOrder=Ascending&N=department%3Arigid-tubing%2Bpart-type%3Aaluminum-tubing
The 0.058 inch wall tubing allows telescoping of tubes that are sized in 1/8"
(.125) increments. The .120" wall thickness allows telescoping of tubes that are
sized in 1/4" (.25) increments. Note that these fit together much tighter than
the mm sizes.
Wes N7WS
On 7/17/2019 7:49 AM, Máximo EA1DDO_HK1H wrote:
> Hi all,
>
> Telescopic Aluminum masts are easy to make using metric tubes.
> Using 2mm wall tubes, then 30, 35, 40, 45, 50, 55, 60, 65mm (and so on)
> external diameters you get the telescopic feature easily, leaving 1mm
> clearance between tubes.
>
> I was trying to do same with "american tubes" but I couldn't find any size to
> get same telescopic thing.
>
> Anyone knows how to make a telescopic aluminium mast using customary tubes?
>
> Thank you
>
> 73, Maximo
>
>
>
> <http://foro.ea1ddo.es/>
>
>
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