[Towertalk] Teflon sources

[W0UN--John Brosnahan]

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:


>share with us Toddles...on a related matter...
>
>I am considering using some scrap pieces of what I think is Teflon
>picked up at a flea market.  I want to use them as horizontal thrust
>bearings on a tall rotating mast...seems like these should be a good low
>rpm choice...
>
>The mast would be aluminum and these would have a hole in the "plastic"
>slightly large than the mast...the stock is about a half inch thick and
>in turn would be bolted to an aluminum plate with a slightly large hole
>than is in the "plastic"...should take care of lateral movement it seems
>and at the same time would not chafe the aluminum mast during rotation.
>
>Is there a concern I should have for ability of Teflon (this might be
>something else but lets assume is what the guy selling it said it was)
>and its exposure to UV - a crucial problem here in FL.