I use a material referred to as "Nylatron" for the bushing in the
Sidewinder; works great! It may be the same as what John refers to; it is
black; it has graphite in it to make it slick, and it is UV stabilized. It
is specialized UHMW for bushing use.
Use a nice, slow RPM on the drill press to avoid melting the material
whilst you bore it out to size. Fastening it to a piece of wood or metal to
secure it while boring on the drill press is a very good idea.
At 03:02 PM 7/29/2002 -0500, W0UN--John Brosnahan wrote:
>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
>>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.
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Robin Midgett KB4IDC
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