[TowerTalk] Joining sections of aluminum mast

[knowkode at verizon.net]

 Dave,
You did not specify the tower. I would not recommend what you are proposing for Rohn 25 or equivalent sized cross section. I did a tower removal years ago that consisted of Rohn 25 with a bottom mounted rotator and aluminum rigid conduit running the length of the tower.The tower was about 70' high if I remember correctly. It made  the tower very difficult to climb. There was not enough room for me to get my boot in deep enough to have the tower rung just ahead of my heel. I was effectively standing on my toes for the whole job. It was an absolute pain to dismantle. Every joint of aluminum had seized so it required a Sawzall. The joints consisted of threaded couplers that had been pinned with bolts.

 Installation won't be much easier. You will need a gin pole to lift each section of conduit to the top of the tower to thread down from above.  You can't couple or pin anything until it is in the tower because it needs to pass through the thrust bearing or the hole in the thrust bearing support plate. You will not have a good foothold during the installation.
That said, if Rohn 45 or larger, the foothold issue will not exist. The only other thing that was done on that tower was the installation of guide bushings fashioned from rotor plates with UHMW plastic collars spaced every 17' or so going up the tower.
73,Jim, W5QM