>From my experience it is not the rotation of the tube that does the
grinding, it is the constant movement caused by the wind that does it. Even
a small gap between the two tubes will make it possible for the wind to
move things a little and after a few years the wear on the aluminium tube
is clearly visible.
Furthermore, thin PTFE sheet as is not a good choice as a "bushing", it
will easily be punctured if the inside of the galvanized tube is not
extremely smooth and normally it is not since the galvanizing process that
makes the surface rather rough. PTFE is just too soft.
73/Peter SM2CEW
At 05:56 2003-04-08 , you wrote:
>A couple of stainless steel hose clamps (one placed above the pointy
>top tube and one below) and overlapping the top and bottom edges of the
>bearing sheet respectively will keep it (whatever the material
>chosen) in place.
>
>Of course, how many rotations of the antenna would it take to reduce
>the strength of the unprotected aluminum mast significantly (say to the
>90% level)? I am thinking that would be a serious rotator workout!
>
>73 de Mike, W4EF......................................
>
>----- Original Message -----
>From: "Don Havlicek" <n8de@thepoint.net>
>To: "Jim Lux" <jimlux@earthlink.net>
>Cc: "(Reflector) TowerTalk" <towertalk@contesting.com>
>Sent: Monday, April 07, 2003 8:19 PM
>Subject: Re: [TowerTalk] Above the Thrust Bearing
>
>
>> Jim,
>> He wants something to fit INSIDE that collar.
>> UHMW sheet isn't flexible enough for that task.
>> The Teflon sheet [about 3-4 mil] will be perfect for his task, and
>> require NO machining.
>> Don
>> N8DE
>>
>> Jim Lux wrote:
>> > Don't bother with Teflon... use High density (UHMW) polyethylene cutting
>> > boards... Less than $10 at your local discount store.. Very good
>dielectric
>> > properties, easy to cut (make sure that saw is SHARP), and almost as low
>a
>> > friction coefficient as PTFE.
>> > Unless you were planning to heat your antenna up hot enough where the PE
>> > starts to flow....?
>> >
>> > ----- Original Message -----
>> > From: "Don Havlicek" <n8de@thepoint.net>
>> > To: "Jerry K3BZ" <k3bz@arrl.net>
>> > Cc: "(Reflector) TowerTalk" <towertalk@contesting.com>
>> > Sent: Monday, April 07, 2003 6:17 PM
>> > Subject: Re: [TowerTalk] Above the Thrust Bearing
>> >
>> >
>> >
>> >>Jerry,
>> >>Get some Teflon sheet and cut a piece to fit. Should last a lifetime.
>> >>Don
>> >>N8DE
>> >>
>> >>Jerry K3BZ wrote:
>> >>
>> >>>I've received several good comments and ideas, thanks. What I'm really
>> >>>concerned about is the aluminum mast and the aluminum tower sleeve
>> >>
>> > wearing
>> >
>> >>>away slowly from metal-to-metal contact. But grease isn't the only way
>> >>
>> > to
>> >
>> >>>keep them from actually touching. What about some sort of "bushing" to
>> >>
>> > fit
>> >
>> >>>between the mast and the sleeve?
>> >>>
>> >>>I was thinking of a section of thin-wall pvc of appropriate diameter
>and
>> >>>wall thickness, sliced length-wise and inserted betwen the mast and
>> >>
>> > sleeve
>> >
>> >>>on opposite sides of the mast, then clamped to the mast above and below
>> >>
>> > the
>> >
>> >>>sleeve. The idea would be for the pvc to be sacrificed and replaced
>> >>
>> > every
>> >
>> >>>few years as necessary. I'm no engineer and I don't even play one on
>TV,
>> >>
>> > so
>> >
>> >>>any comments from those more talented than I?
>> >>>Jerry K3BZ
>> >>>
>> >>>
>> >>>
>> >>>_______________________________________________
>> >>>
>> >>>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>> >>
>> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
>any
>> > questions and ask for Sherman, W2FLA.
>> >
>> >>>_______________________________________________
>> >>>TowerTalk mailing list
>> >>>TowerTalk@contesting.com
>> >>>http://lists.contesting.com/mailman/listinfo/towertalk
>> >>>
>> >>
>> >>
>> >>_______________________________________________
>> >>
>> >>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>> >
>> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
>any
>> > questions and ask for Sherman, W2FLA.
>> >
>> >>_______________________________________________
>> >>TowerTalk mailing list
>> >>TowerTalk@contesting.com
>> >>http://lists.contesting.com/mailman/listinfo/towertalk
>> >
>> >
>> >
>>
>>
>> _______________________________________________
>>
>> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
>
>
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
|