[UK-CONTEST] Gin Poles/Falling Derricks

[Robin Thompson]

Yes thanks for the thoughts Paul ... well the steel/ali aided joint is 20ft
off the ground and water ,if it gets in, can run past freely ... I agree
that there could be a problem over the years - but the stress is all
downwards at the moment - when it comes one day in the future to taking it
all down, I will be very aware of the fracture problems and stand well
clear! Hopefully with a gin pole (no further comment, other than I have
always known it as that as well!) it will all come down in one bit - under
control hopefully !

73
Robin
G3TKF

> -----Original Message-----
> From: uk-contest-bounces at contesting.com [mailto:uk-contest-
> bounces at contesting.com] On Behalf Of Paul_group
> Sent: 23 June 2010 18:42
> To: uk-contest at contesting.com
> Subject: Re: [UK-CONTEST] Gin Poles/Falling Derricks
> 
> On 23/06/2010 17:05, Robin Thompson wrote:
> > I managed to find a couple of feet of steel tubing with the same i/d as
the
> > ali scaffold poles to bridge the join around one of those stupidly
designed
> > couplers - been up for 20 odd years now with no problems...
> >
> > 73
> > Robin
> > G3TKF
> >
> 
> 
> Hi Robin
> 
> Its worth noting for anyone else contemplating using this method of
> connection that un protected steel / aluminium interfaces are quite poor
> for corrosion. this is a concern where it cant be inspected. The
> connector should be radiused at each end to avoid a sharp transition and
> thus fracture point.
> 
> Using a solid section here would be very dangerous as water needs to run
> down the inside past the connection and out of the bottom of the
> structure. Take care if you set the bottom of the tube into the ground
> even by accident, a slug of soil will prevent drainage. Look from time
> to time that water isn't trapped. This is by far the most common failure
> point of vertical tube structures - assuming they were designed properly
> and not overloaded in the first place.
> 
> When you have climbed a 150 foot tubular mast dragging a gin pole up
> behind you it tends to focus the mind on how good the connectors are and
> whether there has been any frost damage. Of course we are no longer
> allowed to climb them!
> 
> 
> 
> Regards Paul
> 
> 
> 
> >> -----Original Message-----
> >> From: uk-contest-bounces at contesting.com [mailto:uk-contest-
> >> bounces at contesting.com] On Behalf Of Pete Lindsay
> >> Sent: 23 June 2010 13:26
> >> To: Tom Boucher
> >> Cc: uk-contest at contesting.com
> >> Subject: Re: [UK-CONTEST] Gin Poles/Falling Derricks
> >>
> >> Tom ,
> >>
> >> Just use a standard scaffolding coupler they are cheap and very
> >> strong. I have had many "jaybeam" type couplers fail but since
> >> changing to these 20 years ago not a single problem since. When we
> >> have had the occasional "incident" the coupler has never failed even
> >> when the scaffolding pole has ended up looking like a banana !
> >>
> >>
> >> Pete, G4CLA
> >>
> >> On 23 June 2010 11:51, Tom Boucher<tom at telemetry.demon.co.uk>  wrote:
> >>> Does anyone know a source of external 2 inch mast couplers without
that
> >> weakening slot? They do exist because I have one. I also have some
> > internal
> >> expanding couplers which are probably stronger than the external
things.
> >>>
> >>> Tom G3OLB
> >>> _______________________________________________
> >>> UK-Contest mailing list
> >>> UK-Contest at contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/uk-contest
> >>>
> >>>
> >> _______________________________________________
> >> UK-Contest mailing list
> >> UK-Contest at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/uk-contest
> >
> >
> >
> > _______________________________________________
> > UK-Contest mailing list
> > UK-Contest at contesting.com
> > http://lists.contesting.com/mailman/listinfo/uk-contest
> >
> >
> 
> 
> --
> 73 de Paul GW8IZR IO73TI
> http://www.gw8izr.com
> 
> _______________________________________________
> UK-Contest mailing list
> UK-Contest at contesting.com
> http://lists.contesting.com/mailman/listinfo/uk-contest