[TowerTalk] Joining sections of aluminum mast
Jon Zaimes, AA1K
jz73 at verizon.net
Sun Aug 21 07:34:16 EDT 2022
I worked on a 40-foot BX tower in Maryland that had a long aluminum mast with the rotor mounted about 10 feet above ground.
The mast sections were coupled with these: https://www.penningerradio.com/product/aluminum-clamp-it-mast-clamp-2-dia/ They held the mast securely and had been in service several years.
The mast went through the original rotor plate in the top section, but without any bearing or bushing there. The mast had enough wobble that the sharp edge of the steel rotor plate had over time scored a deep grove in the mast. It was severe enough that it would have sheared the mast off before too long. We remedied by cutting off a short piece of mast at the groove and expanding the hole in the rotor plate so it couldn't rub the mast.
Depending on the height of your tower, you may want to consider an intermediary bearing (or more than one) to stabilize the mast.
73/Jon
Jon P. Zaimes, AA1KTower climber for hireFelton, Delawarehttp://www.aa1k.us/Cell: 302-632-2353 Reviews of AA1K tower work on eham website: http://www.eham.net/reviews/detail/12922 Hug your favorite tower every day, and always stay connected to it.
-----Original Message-----
From: Dave KØEKL <k0ekl at outlook.com>
To: TowerTalk at contesting.com <TowerTalk at contesting.com>
Sent: Sat, Aug 20, 2022 7:08 pm
Subject: [TowerTalk] Joining sections of aluminum mast
To ease maintenance I want to relocate my rotator to the bottom of my tower.
The existing mast is 2" diameter ¼" wall 6061-T6 aluminum tubing. The rotor is 8 feet below the top of the tower / thrust bearing.
What is the best way to join additional lengths of tubing together to reach the bottom? I'm thing about buying tubing that is 2" ID, cutting it into 18" or 24" sections, slitting it and slipping it over the 2" OD sections to be joined and clamping with SS U-bolt clamps like those sold by DX engineering. Will this provide enough coupling friction between sections to prevent slippage?
Also, can I get away with using 1/8" in wall 2" OD tubing from the existing mast to the base of the tower or should I use ¼" wall all the way to the bottom.
Thanks.
-Dave K0EKL
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