Between the sleeve and the mast, I use a fhin piece of polyethylene sheet
cut from one of the new "disposable" cutting boards they sell in Walmart
and supermarkets. To prevent wear, I wrap it around the mast and cut it so
it doesn't overlap, then slide it in between the mast and the sleeve to
act as a bearing. I checked it after a year and there was no noticeable wear.
Jerry, clever idea. Most of the cutting boards I have seen are made of
UHMW (ultra-high molecular weight) polyethylene which is also used for
bearings. I have heard that they are used in the trucks (wheel assembly)
of railroad cars.
I have made my own bearings from UHMW by sawing a square piece
of one-inch thick stuff to size and drilling it to the bolt pattern for a
Rohn TB-3. Works well and I have not seen much UV degradation,
even at Colorado elevations, over the 12 years they have been up.
MUCH cheaper than the commercial stuff. To date I have only used them
for side-loading. But with the right setup they could take the top loading
as well. Just need to cut a disk of SS or aluminum sheet like a big
washer and put it on top. Then place the weight on back-to-back
muffler clamps so they support the mast and rest on the plate which
sits on the UHMW! ;-) (word = milli-picture)
I use a cutting board for my motorcycle stand. That way I can ride in
and rotate the bike 180 deg and ride back out. The bearing turns on
the smooth concrete floor pretty well. But your sheet idea sounds like
a winner to me for some applications I have.
--John W0UN
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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.
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