Filling the pole/tube/mast with concrete?

[archive10]

All the Channel Master and Prodelin manuals have a section on making a suitable concreted-in pole for mounting the dish on.
(Interestingly - the text and diagrams are almost identical, to the degree that one would think it's the same guy writing for both companies!)

But that all state that the pole that is concreted in needs to be filled completely with concrete.
I assume this is an easy way of keeping moisture out of the pole, now that the cement mixer is out anyway.
(It probably also adds rigidity to the pole. (which is a hard thing to write without thinking of a slightly different topic.))
(And funny how it's called a cement mixer when you are making concrete... ??)

But... what if the pole is mounted on T-K brackets or similar?
Should we concrete that stuff up too? and giving the add in weight, should we consider a scenario where the pole is not actually concereted into the ground, but resting on, say, a garden slab, to take the load, but still filled with concrete?

 

[Analoguesat]

Vipersan filled his steam pipe mounting pole with oily sand when he was repairing the damage to his big "Christina" dish a couple of years ago to keep the damp out. The previous mast rusted through at ground level & snapped in a storm.

 

[purplemarina]

i used waxoyl (car rustproofing product) that i had left, for protecting the interior of my ground mounted pole. the wall thickness is 3mm so it dosent flex it also has brackets supporting midway. the cm. polar mount wraps around the pole and clamps over a large area so no chance of distorting the pole by over tightening. i have filled a pole with sand to try and reduce motor noise before, it helped but it still resonated.

 

[Captain Jack]

I have filled my ground/concrete mounted pole with concrete many years back for rigidity more than water ingress and would do it again. I like VS's idea of filing it with oily sand too - perhaps for next time.

Sten, what's your reasoning behind wanting to fill a wall mounted (be it resting on the ground or not) pole with concrete? Stability can be improved with extra brackets - unless the top of the pole is high above the last bracket (say over the roof gutter). And water will just leave at the bottom of the pole as it would have nowhere to pool.

Waxoil is a good idea - probably not needed if the pole is galvanised or stainless steel but always good to have belts and braces approach.

 

[TJExcalibur]

Bloody hell. Bit risky filling a wall mounted pole with concrete. It would be bad enough if it came adrift without adding extra weight. Pour some oil through it to prevent rusting as I did with my 1.2 dish and added a plastic top cap.

 

[Terryl]

I would not fill a wall mounted pole with concrete this may exceed the manufactures spec's on what the mounts can hold, if you have rigidity problems then a second pole could be inserted up through the main one, or a thicker pole should be used.

But filling a ground mounted pole (one that is in-bedded into a hole the ground) is almost a must, this helps with offsetting the weight of the dish and polar mount and give rigidity to the pole it's self.

For a 3 inch (76 mm) or 4 inch (100 mm) pole I use nothing smaller then a scheduled 80 rated pipe, for the smaller 3" pipe the wall thickness is .3o inches (7.6 mm) for the 4 inch pipe it's .34 inches. (8.6 mm)

This type of pipe is very very hard to bend, but could sway at the top if not filled with concrete.

If you going to fill the pipe then mix the concrete soupy, this will help you pour it in, and be sure to tap on the pole with a hammer as you fill, this drives out any air that may have been trapped, do not mount anything to the pole for at least 72 hours after the last bit of concrete is poured.

 

[Lazarus]

I'm so glad I'm not good at spotting euphemisms.

 

[TJExcalibur]

I'm so glad I'm not good at spotting euphemisms.

Isn't a euphemism one of those strap on things that women use to think they are with a man?

 

[thecaretaker]

I have tried various types of pole (TK brackets mounted on a wall not ground mounted), I've ended up using a thick galvanised scaffold pole with a plastic end cap on the top. No movement in the pole and I get a really solid grip on the dish bracket. It has been up several years now with no signs of rust even though I live next to the coast with salty sea air. Chat up a friendly scafolder, it won't cost you too much.;)

 

[Terryl]

What I use for larger antennas is 2" or larger ridged conduit, it's galvanized and is very very hard to bend, can be found at most larger hardware stores.(along with mounting hardware)

The bigger stuff comes with a threaded coupling if you want to go taller the 10 foot, but what I do is sue a 2-1/2 inch base pole then a bell reducer to an 1-1/2 both are ridged conduit.

Here is my setup for kU band, it's a 1 meter dish and motor.



The bottom 2" mast is fixed to a base of concrete, then the 2" to 1-1/2 bell reducer, a wall mount then the top mast is cut to 5 feet, a standard chain link fence cap tops it off

 

[archive10]

Sten, what's your reasoning behind wanting to fill a wall mounted (be it resting on the ground or not) pole with concrete? Stability can be improved with extra brackets - unless the top of the pole is high above the last bracket (say over the roof gutter). And water will just leave at the bottom of the pole as it would have nowhere to pool.

The only pole I have concreted into the ground is in Sweden, and I *didn't* fill this with concrete after putting it up.
Have been wondering ever since...
Nevertheless it is fully galvanised, so even if rain did get past the Channel Master mount head, it would probably make no difference.



I hope to soon be remounting some dishes here in frosty old Denmark (probably when spring comes!) and one of them may be mounted on a 3" pole that will be firmly attached to a a wall using T/K brackets (which BTW are impossible to come by in DK - will have to order in UK).

One of these is going to be an above gutter job on a 3m pole, but I reckon 2xK + 1xT will do the job.
This will most likely be resting on the ground in a concrete "foot", but not actually concreted into the ground (I hate digging, especially next to lovely and very expensive foundations of my newly built terrace + garden house).

So I was wondering what the purpose of the concrete-in-the-tube was - but seeing the answers above, I think rigidity is as much a part of it as the moisture-avoidance...

TBH I was not thinking of filling a purely wall-mounted pipe with concrete. That would be overdoing it, I think ;)

 

[archive10]

Here is my setup for kU band, it's a 1 meter dish and motor.
The bottom 2" mast is fixed to a base of concrete, then the 2" to 1-1/2 bell reducer, a wall mount then the top mast is cut to 5 feet, a standard chain link fence cap tops it off

Looks good, and sounds convincing, but doesn't it flex wildly in gale force winds?

 

[beavs2112]

I'm not really sure why the manufacturers specify to add concrete into the pipe. I think filling the pipe that is embedded in the ground is a waste. I really don't think the concrete adds much rigidity. I think if you want more rigidity get a thicker walled pipe. The reason I say this is I read in an issue of Coops Satellite Digest (Bob Cooper is one of THE American pioneers in home satellite systems from the '80s) that all the concrete did was cause the pipe to fail at the seam or elsewhere. He installed several different types of sat dishes (mesh/fiberglass/steel) in various sizes from 8 to 20 feet in diameter on an island in the Caribbean where he had a residence before hurricane Kate. Then after the hurricane passed he surveyed the resultant damage to the antennae. The results are in the January 1986 issue of Coops Digest magazine starting on page 36. I'll put the pertinent quotes from the article below.

"We also thought that if you take a 3 or 4 or 5 inch piece of pipe and fill it with concrete, allowing the concrete to harden and stiffen the pipe, you will add considerable strength to a pipe mount. Not true. Calculations suggest that if you fill a piece of pipe with concrete, you are gaining between 10 and 12 percent additional pipe-stand strength at the most. Pipes filled with concrete tended to split along vertical seams or where stresses simply made seams. Concrete filled pipe was ultimately not measurably stronger nor more resistant to wind collapse than pipe left alone. We won't bother filling any more pipe with concrete"

"Filling pipe (mounts) with concrete is a waste of time in most situations; you are far better off spending the same money and time bracing the pole back to the ground with three rugged support legs"

As far as rust prevention coating the inside of the pipe with something is a good solution.
I put a small amount of concrete in the tops of my ku dish poles to stop the pipe crushing when you tighten the bolts on the ku diseq motor brackets. it doesn't add too much weight. I wouldn't advise filling the whole pipe with concrete however.

Kevin

 

[Channel Hopper]

All the Channel Master and Prodelin manuals have a section on making a suitable concreted-in pole for mounting the dish on.
(Interestingly - the text and diagrams are almost identical, to the degree that one would think it's the same guy writing for both companies!)

That is because neither company produces the king posts or non penetrating mounts, these are supplied by Baird of Iowa.

 

[Terryl]

Well the reasoning behind putting concrete in the pole is to add rigidity to it, think of it this way.

Ttake a pole that is 10 to 15 feet long (3 feet or so underground embedded in concrete) now add the 100 to 200 pounds of dish and polar mount to the very top and offset it to one side and you have a big load on the base, now take a look at the sail area of this dish it can be 10 to 15 square feet or more, and it moves back and forth, even more in the wind.

At the very base of the pole where it first enters the concrete base is where all the action is going on, with the offset load and the motion of the dish as it pans plus any severe wind loads this adds up to a lot of stress at this point, over time the stress can cause micro fractures and it very well could fail if it is also attacked by water from both inside and outside.

On some of the very large dishes I have installed there is an extra thick collar around the last ten to twelve inches of mast for support for the motors if it is a movable dish, and we still fill it to a point above this collar for extra support.

Now you could use a thicker walled pipe, but how many of you have tried to lift a 10 foot 4" schedule 80 pipe up to drop it into a hole 24 to 36 inches deep?

It's not a one man job.