Thinking of changing my megatree hardware to aluminum

[Greg.Ca]

Because of the weight of steel, I want to change my current mega tree mast pole from steel to aluminum. It is currently 1 1/4 diameter about 20 total feet of steel pipe with a 10 foot piece of steel pipe on top of another 10 foot piece of steel pipe. These two pieces of ten foot steel pipe is joined in the middle by a very short steel 'coupler' that is female threaded that both of the 10 foot sections screw into. I have always thought that 1 solid piece is way better than 2 pieces threaded together by a coupler.

There is a aluminum vendor here that sells a 20 foot section of aluminum pipe either 1 1/4 or 1 1/2 diameter in either schedule 40 or schedule 80. It appears to be thicker than the steel (schedule 80) and 1/3 the weight. I'm changing the hook head to have the center section 'pinned' with two holes so that the hook head can be attached ANYWHERE on the mast pole. The old hook head center section was threaded and would only screw into the end of the threaded mast pole. This way, with the new hook head center design, the center section being a outer 'sleeve' over the mast pole, has more 'adaptability' if I want to slide the hook head higher or lower on the mast pole. The tree topper star has already been changed to aluminum and with it's design, I can slide it up or down the upper aluminum 3 foot mast pole.

See the photo. In the 2nd photo, you can see the mast pole made out of steel and the existing hook head made out of steel Out of the top of the hook head is an aluminum 3 foot pole in which the aluminum tree topper star frame is threaded into the top of the hook head. I eventually want everything to be made from aluminum. The steel is just too heavy. Very dangerous to install or remove. Too top heavy!!. Once this thing starts to tip, it's just an accident waiting to happen.

I can order a 20 foot section of either 1 1/4 or 1 1/2 in either schedule 40 or more preferred schedule 80. The schedule 80 is thicker than steel, more robust, and 1/3 the weight. Of course the cost is MUCH more.

Is there any reason why I shouldn't go to aluminum? With a larger hook head every year, tall height and the tree topper star frame up there, it is VERY top heavy and difficult to handle when installing or removing the mast pole with all that stuff on top. Any negatives on aluminum? --Greg---

 

[Greg.Ca]

Ignore the first photo, what the heck was I thinking? --Greg--

 

[the grinch]

From my experience is steel can flex and bend and return to original shape but unfortunately yes much heavier . Aluminum much lighter but doesnt flex and bend as well will crack and break hence why most aluminum pipes rails etc are generally ribbed in some way to give rigidity. So generally the thickness of aluminum should be greater than steel to attain same strenght but will be much lighter.

 

[AAH]

I would look to see if you can find a flagpole in aluminium. Rectangular hollow section (RHS) and round have very little strength when it comes to compressive loads and as soon as it flexes a little it loses what strength it has as the load moves off the line of maximum strength. You can get lightweight aluminium flagpoles cheap and because they are a non parallel profile they are much stronger than a parallel sided profile. For 20 feet with what you have hanging off that pole I wouldn't even consider going to under 2" diameter. You are better off going to a larger diameter with a smaller wall thickness than a smaller diameter with high wall thickness.

 

[damona]

From my reading the rule of thumb is aluminum needs to be 20% thicker than steel for the same sort of strength


The down side, is you can not mix metals. e.g. Aluminum and steel, they will rust. You can mix them if you protected them from touching each other with plastic for example. Paint might do it as well.


I tried to put my mega tree up this year, it was to heavy with the lights on, as I walked under the pipe to push it up, I ended up being the pivot point, and the bottom lifted up into the air. i.e. 50kg of lights at one end, and no counter balance at the other end. Need to find a solution for 2016.

 

[fasteddy]

From my experience flag poles can be risky as most are built with thin walls and in sections because they only need to carry the weight of a flag. Once you have all the weight and wind drag of the lights then this can put considerable stress on the aluminium pole and they can fail at the section joins.
If you plan to use an aluminium pole then you need to get something with a thicker wall and as one complete length and support it with guy wires at 2 levels to ensure you don't end up with disappointment during a large storm or strong winds