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[TowerTalk] blocks

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Subject: [TowerTalk] blocks
From: (Pat Barthelow)
Date: Thu, 16 Apr 1998 22:20:11 -0700 (PDT)
HI Russ,

We found a very small, deceptively strong block at a local marine supply
store.  Stainless steel, and nylon body/wheels with ball bearings, the
thing was not too
expensive...about $12.00. The pulley wheel was only about 1-1/2" diameter,
the block was rated at 2000 lbs working load.  We loaded it while lifting
a very heavy homebrew 20 m 4 element yagi.  Though strong, and well built,
it worked, but seemed to add significant drag friction to those of us
armstrong techniques to lift the beam.  The line used was new,
marine type, braided dacron,
also strong enogh, but only 1/4" or so diamater..  This is where I learned
of the advantages of larger
diameter rope, and larger diameter blocks....The rope was too thin to
handle well, with the 100 + pound load, and the small pulleys seemed to
add quite a lot of friction.  We were unsuccessful in lifting with this
tackle, so we acquired some larger pulleys, and made a multiple pulley
assembly, giving a 2:1 mechanical advantage...and the beam went right
up....I later looked at a rigging book, and found out that the diameter of
the  block should be 7 to 10 times the thickness of the rope, for
best/safest operation...our first rigging system did not do this....

BTW, the price of the Marine Grade blocks went up exponentially with would not even want to know what a 3" or 4"
Stainless/Nylon, single or dual
block marine grade pulley costs....

73, DX de Pat, AA6EG/N6IJ 
"The Contest Station from the Government"

Marina Amateur Radio Contest Station; N6IJ
599 DX Drive
Marina CA 93933

On Thu, 16 Apr 1998, RUSSELL THOMPSON wrote:

> I am lookin for a very light snatch block and would like it to be rated
> at 1000 lb. safe working load. can anyone tell me where to find one

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