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[TowerTalk] Long Masts -- Intermediate Bearing?

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Subject: [TowerTalk] Long Masts -- Intermediate Bearing?
From: (Jim White, K4OJ)
Date: Fri, 3 Apr 1998 08:02:12 -0500
One of the neat things about rotors and beams brought to light by K0PP was
that if you are using a typical rotatator it turns at about 1 RPM.  Because
things are moving slowly the same kind of tolerances normally sought for
something like a car axle or drill press motor are not needed.  If you are
a little out of whack it is no is not spinning like crazy so
you should be fine whit "amateur" standards.

On the second shelf (the intermediate one) we use a sheet of aluminum from
the scrap yard cut to size and the use geometry to find its center.  After
making a triangle whose sides are equal in length, take the length of the
side and "cut it in half", at this midpoint use your square to construct a
right angle. Repeat this for all three sides....the intersection of the
three right angles in the center of the plate is just that....where your
hole should be.  This was a proof from geometry class...something along the
lines of the bisectors of the sides of an equilateral triangle will
intersect at the center....whatever....cannot believe I remember stuff like
that from a quarter of a century ago - guess what Mom and Dad said was will not use everything you are taught in school, but some of it
you do!

While at the scrap yard pick up a piece of angle stock to bolt onto the
corners, and to also provide a location for your u-bolts which will attach
to the tower legs.

Another trick I like is to make the plate a little bigger than it should be
and then notch out for the diagonal braces.  If you did this you can then
put the plate such that it sits on the horizontal part of the tower's cross
braces and the vertical forces that bearing may have to carry when you do a
change out of the rotor are passed to the welded rung....not the ubolts,
the u-bolts now just have to keep things centered.  By now you are asking
why those angles in the corner don't prevent the plate from dropping so
close to the horizontal....another trick....mount the angles on the top
side of the plate, so they "stick up">

This has worked very well for us at the W1CW/W1YL station.  I feel very
comfortable with the end result.  The latest frill we have added but I
haven't had to use yet is on the top plate of the latest top section
installed there are several small holes in it.  These holes match the base
of an automobile jack I bought at a flea market.  When it is time to boost
the mast to do a rotor changeout next time I will be able to bolt the car
jack to the top plate - align the boom over it and the mast will go
vertical as I raise the is ready to boost - no
slings/clamps/comealongs will be needed.

Now is a good time to do this stuff...before you go vertical, and wish you
had done it!

Less than a month til the Florida QSO Party!

73, see you in the FQP

Jim, K4OJ

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