[TowerTalk] Joining sections of aluminum mast

[Grant Saviers]

A lot depends on what rotator and how tall is the tower?

I would recommend machined internal sleeves either of solid 6061 or 
tubing with enough wall thickness to machine the od to fit the mating 
tube id's.  I don't think slitting and expanding 6061 is practical with 
adequate wall thickness - min 1/8".

With a top thrust bearing, there will only be the tube or pipe weight on 
the bottom rotator.  That tube will only have to handle the rotation 
torque loading, no side bending from wind.  Probably 1-1/4 NPT pipe 
would be strong enough, backyard engineering.  Threaded couplers with a 
3/8 gr5 thru bolts in drilled holes to prevent unscrewing.

However, I'm not in favor of adding a long torque tube spring to an 
already complex tower-rotator-mast-boom-elements dynamic system.

Grant KZ1W

On 8/20/2022 16:08, Dave KØEKL wrote:
> 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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