I have had a Teflon bushing in my tower for nearly 20 years and it works
great. The top section has a 2.0 inch opening and the aluminum pipe is
1.66. It did take a lot of machining as it was made from 2 inch round stock.
>Date: Mon, 29 Jul 2002 15:02:27 -0500
>To: Jim White <email@example.com>
>From: W0UN--John Brosnahan <firstname.lastname@example.org>
>Subject: Re: [Towertalk] Teflon sources
>Cc: "'Tower Talk'" <email@example.com>
>The proper material to use for mast/tower bearings is UHMW polyethylene
>Ultra High Molecular Weight Polyethylene is used for all kinds of
>bearings. The white version appears similar to Teflon although not
>as slick. And it doesn't cold flow like Teflon.
>There are gray and black versions that are UV stabilized. But I just made
>my bearing brackets in such a way that they are out of the direct sunlight
>and have had no problems with the white bearings (made with 1 inch thick
>UHMW) in over ten years of service with a number of large antennas. Such
>as 8 element 15 meter beams on 60 ft, 3 inch diameter, booms. Never needs
>to be lubricated and is CHEAP. And doesn't rust of course.
>The mast hole on UHMW can be "drilled" using a hole saw in a drill press.
>Pretty easy going and makes for a cheap machining job.
>Good Luck--John W0UN
>BTW I would never use any material that I wasn't sure of. And I wouldn't
>use Teflon in any case. W7RM was an early adopter of the UHMW bearings
>and has had very good service over MANY years.
>At 03:13 PM 7/29/2002 -0400, Jim White wrote: