PVC Anenometer Mast

[serowe]

Sand is going to make it a lot more dangerous. Apart from the weight which the pipe was not manufactured to withstand, it is also most likely to absord water trickling doen from the top and, unjless you close off the bottom, will simply run out the bottom taking with it the sand.

[krmidas]

Sand is going to make it a lot more dangerous. Apart from the weight which the pipe was not manufactured to withstand, it is also most likely to absord water trickling doen from the top and, unjless you close off the bottom, will simply run out the bottom taking with it the sand.

Both ends of the pipe have been capped. I'll wait and see if there is decreased swaying. If not, I'll empty the sand and try several wooden dowels.

[serowe]

Again keep in mind you want rigidity with minimum weight - dowels offer this, sand is definately not rigid. All it is, in this case, is ballast and a dampener i.e. it is still very flexible and therefore liable to bend - especially under stress.

[krmidas]

I found 4' long wooden dowels that fit perfectly inside the PVC tube (not loose enough to rattle around, but not so tight that I needed a hammer to get them in there). Inside my 10' PVC pipe, I inserted 2 and 1/2 dowels, then I capped both ends of the pipe.

The weight of the pipe and swaying is significantly reduced. Not perfect, but much better, and I suspect much sturdier than before. As far as the swaying issue, I'm limited by the weakest link in the chain, which in this case is the wooden mailbox post that everything is mounted to.

Thanks for all the advice. Anybody need a big bag of sandbox sand???



-Tom

[serowe]

I found 4' long wooden dowels that fit perfectly inside the PVC tube (not loose enough to rattle around, but not so tight that I needed a hammer to get them in there). Inside my 10' PVC pipe, I inserted 2 and 1/2 dowels, then I capped both ends of the pipe.

Should have mentioned one way to 'join' multiple dowel pieces is by using some silicone dabbed on the end of one, then pushing the next section in until it 'bites'. Do the same all along and whilst not as rigid as the dowel itself, can help to also form a seal.

[Solorize]

FYI.

I've just foud this place on the net based in the UK , that has cheap circular and square tubes.

http://www.aluminiumwarehouse.co.uk/Alu ... fAodzHFDxw

I currently have the main part of my mast as a large alumimium pole, with an additional 3/4" steel crome plated
pole fixed to it. Which has already started to corrode, due to dissimilar metals.

So I think I will buy a Aluminium Round Tube 3/4 in x 16 swg 2500mm (£2.83), to replace the top section of my mast
to keep both poles Aluminium.

I was debating whether to just buy a large square pole of 5000mm, but decided against it as I would have
to get it delievered to my work, and then try and get it in my car to get it home which would never work

[Gina]

That's the firm I get my aluminium from. Great value and quick delivery but they do charge £15 delivery which means you want to get a decent sized order together to make good overall VFM.

[Solorize]

Yes, the square section works well for me with no guy ropes required. I image a triangular section would work as well if not better than square but it's a bit hard to find a triangular extrusion over 5 metres long
Triangular would be less wind resistance too.

Terry,
I may go for a 5000mm 40x40 Aluminium pole now having read how yours
does not wobble around, rather than having two round poles attached.

Can you let me know what wall thickness your 40x40 square section is?

I guess it would be either 3.25mm (10 swg) or 1.6mm (16 swg)

Just want to make sure I get something that is not going to need
me to use guy ropes etc..

[serowe]

Planning on putting up a 5 metre pole (regardless of shape) without guys is a law suit waiting to happen. Not to mention the it isn't going to be stable enough to ensure any data collected from the top of it is accurate - it WILL move around which means any woind data from instrument(s) on top of it will not be stable and can only be taken with a grain of salt as to their accuracy.

[Super-T]

I can't remember the gauge but Looking at the base of the mast from underneath it looks to be about 3mm. I'll see if I can find the invoice for the Aluminium.
Wind movement isn't a problem and even if it was, how accurate is a Fine Offset anyway? I prefer the "pinch of salt" measurements as they are, because in the local environment there are to many variables anyway.

[serowe]

I can't remember the gauge but Looking at the base of the mast from underneath it looks to be about 3mm. I'll see if I can find the invoice for the Aluminium.
Wind movement isn't a problem and even if it was, how accurate is a Fine Offset anyway? I prefer the "pinch of salt" measurements as they are, because in the local environment there are to many variables anyway.

Which begs the question then - why bother even putting it up if you aren't concerned about accuracy (general 'you' btw)

http://en.wikipedia.org/wiki/Fatigue_limit

And - again - putting up a 5 metre high pole of AMY type without guys is sheer stupidity.

[Super-T]

I have it up to catch the hot air coming out of Victoria.

[Solorize]

This and a few other threads has got me thinking now
which pole would be best to go for, a square section or a circular
section, as well as what guage would be best to go for.

i.e. which is the best combination of section and wall thickness
would be best to resist wind movement.

Obviously a thicker guage would mean that it would
make the pole heavier, but would that make it sway in the wind
more or less? or would it make it more rigid and to be able to
prevent swaying?

[mcrossley]

iirc wall thickness is largely irrelevant to stiffness, certainly for tubes it is the diameter that counts. Wall thickness of course matters for load bearing.

[wd40]

iirc wall thickness is largely irrelevant to stiffness, certainly for tubes it is the diameter that counts. Wall thickness of course matters for load bearing.

Mark, I would have to disagree if I understand the full meaning of the quote.

Randy