As far as bolts through the mast to connect portions of the mast
together, I do not
think a straight bolt will be satisfactory as it well work loose. Using
two will improve
the situation. I prefer to use a cone insert such that as you tighten
the bolt it pulls
the cone into the mast and there is no place for the joint in the mast
to move.
The cone is like a ice cream cone with one end having a .75 inch OD and
a .50 ID and the
other end having a .625 in OD and a .5 in ID. On one side of the mast
drill a 5/8 inch
hole and put the cone in. On the other side drill a .5 inch hole. Now
put your 1/2 bolt
through the cone on one side and through the 1/2 hole on the other side
of the mast and
tighten.
Another way to do it is with a flex coupling where you use a piece of
1/2 in conveyer
belt as your coupler between the two portions of your mast. On each
piece of mast weld
a piece of flat bar horizontally for connecting to your coupler.
A coupler will take the shock out of the system and will be kinder to
your rotator. The
antenna may move around a bit as your torsion coupler twist but this is
a good thing.
You want flexibility in large masts so that there are no sudden stops or
starts.
If I can make it clearer with a picture or sketch contact me directly
and I will see
what I can do.
Denis Ve6Aq / Ve6FI
"J. Kincade" wrote:
> Wanted to bounce an idea off the collective list brainpower:
>
> I read about exotic and complicated ways to hoist the mast up to work on
> rotators. It would be extremely nice to be able to remove my rotator without
> having to hoist/move the mast vertically at all. My new 45G setup will have
> 2 rotor shelves/TB-3's and a 21' mast (10' out the top, 11' inside).
>
> I'm thinking of a short steel tubing sleeve with an ID that will just slip
> over the 2" OD of the bottom of the mast. Bottom of the mast and top of the
> sleeve would be carefully drilled for a hefty galvanized through-bolt. When
> removing the rotator in the future, I should be able to just pull the
> through bolt and slide the sleeve up, temporarily slipping the through bolt
> back in through a second hole in the bottom of the sleeve to hold it up out
> of the way, pull the rotator, etc. The second thrust bearing and a muffler
> clamp with a piece of angle welded to it U-bolted to a tower leg would keep
> everything from flopping around while the rotator is out, and add some
> safety against vertical mast slipping. The Yaesu 1000 is self-centering and
> adjustable to fit about any size sleeve in this application. Or, as an
> alternative, maybe some sort of easily removable heavy duty rubber coupling
> is available that would simply fit between a short rotor stub of 2" mast and
> the remainder of the mast. Don't like that as well, though, I'd fear
> excessive flex might cause constant twisting around of the antennas in the
> wind, unless the rubber coupling was really stiff.
>
> Is anybody using a setup like this, and how is it working? The only negative
> possibility I see is the top of the steel sleeve might permanently deform
> from longterm bolt pressure, and be difficult to slide up. Maybe a single
> slot in the sleeve at 90 degrees from the bolt holes for springiness would
> help prevent that.
>
> Comments welcome!
>
> 73, Jerry W5KP Mustang, Oklahoma
>
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