On 4/19/2013 6:38 PM, Pete Smith N4ZR wrote:
Don, K4ZA rigged a very elegant device using a basketball hoop to manage
a tall mast while raising it with a gin pole and dropping it down
through a thrust bearing. Don't have any pix here but maybe Don can oblige.
You use a ring at the top of the gin pole. when you raise the mast that
ring keeps the mast from turning over when at the top of the lift.
A ring just above the thrust bearing also aids the operation.
When lifting mast you have to stay above the balance point to keep the
mast vertical. The hoops aid in keeping it vertical and in essence it's
like gaining a couple more feet of pole.
It's not with out risk and it's not without additional effort, and it
does take a bit more skill, but I've use this approach many times.
Currently I use a 24' gin pole with a two piece mount. It's heavy, so
the extra reach which is very handy and convenient does take more effort
The pole is a stock length of either 1/8", 3/16", or 1/4" wall 6061-T6
depending on what I need for strength. Normally the 1/8" is plenty
strong if the pole isn't running extended. It'd probably be handy to
use a half length piece with 1/8" wall as it'd be about a 1/4 of the
weight of the 24' X 2" X 1/4"
73
Roger (K8RI)
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73, Pete N4ZR
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On 4/19/2013 11:39 PM, K8RI wrote:
On 4/19/2013 3:26 PM, K7LXC@aol.com wrote:
Howdy, TowerTalkians --
Tnx for your inputs but I think I need to describe what I want
to do
in more detail.
There is a heavy 20' mast sticking out of the top of a pointy
top 45G.
What I want to know is if by lowering the mast down thru the middle
of the
tower, if at some point you can exit the mast thru the face of a tower
section? I haven't tried it and doubt if it could be done but I
wanted to see
if someone in the group has done it or attempted it. Tnx.
I use 24' lengths of 2" DOM in both 45G and 25G. I think You'd have to
remove 2, if not three consecutive cross braces to feed one out the
side. IIRC one isn't enough as there is very little bending moment in
the mast.
We has one slip out of the grab. It made it all the way to the bottom
with no problem and didn't appear to even bounce off any braces
although it did hit the guy anchor rings on the way by.
73
Roger (K8RI)
Cheers,
Steve K7LXC
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