Bizarre Mounts!

[madrat]

I concure (thats a big word, brain must be working today)needs some kind of support half way up or in a strong wind you dish will be waving at you

[Baj1936]

During my search for a 50 mm. scaffolding pole, I discovered that there are at least three sorts, aluminium, light duty steel (with 0.2mm. wall thickness) and heavy duty steel (with 0.4mm. wall thickness). I hope you are using a heavy duty steel pole. Even with the heavy duty steel pole I think you will have problems.

I calculate that at a wind speed of 30mph. the load on your 90cm. dish will be 14 kg. or 31 lbs. This load is proportional to the square of the wind velocity; so that at a wind velocity of 60 mph. (not common but not rare either) the load on your dish will be 56 kg. (123 lbs.). The torque on the base of your 10 ft. pole at a wind speed of 60 mph. will be 171kg.m. or 1,230 lbs.ft. Imagine a 9 stone man using a 10 ft lever to lift a car - no problem for the man but a problem for your pole.

You must also bear in mind that continuous flexing of the pole in even moderate winds will result in metal fatigue and eventual failure.

If you attach your pole to your shed the load on the shed is given by:-

Shed Load = Dish Load multiplied by Length of pole divided by Distance of shed bracket to ground

So at a wind of 60 mph. and a bracket 5 ft from the ground:-
Shed Load = 56 x 10 / 5 = 112kg. (246 lbs.). Imagine installing a shelf to take the weight of a 17 stone man.

When concrete sets it shrinks slightly - this can take several weeks. There is thus the possibility that your pole will rotate in its base over time. This is something to bear in mind in the future if your dish goes out of alignment.

As has already been suggested, lower your dish, as far as possible, to the ground and provide extra support for the pole, as high up as possible.

[madrat]

Or if you cant lower it brace the main pole to form a /|\ tripod shape round the main pole.

[Robbo]

Originally Posted by BGonaSTICK

@Robbo, did you get my PM?

Yes, I have replied.Cheers!

[nousernamesleft]

Wow! Some wind force statistics! It was windy yesterday and it does move a little. I will fit some sort of bracket to the shed but will need to reinforce the inside somehow. I also have the option of a support from the fence post but I put those in so they are not too solid.. Probably doesn't need to be that high - just sort of plonked it on yesterday morning to get it out of the kitchen. Thinking of geting some sort of quick release gadget for the pole bracket so that I can lower it quickly in case of gales. Marking the pole in the right place would mean easy reallignment so thinking that would be a good idea. Maybe a quick release mountain bike wheel spindle would do..

[BGonaSTICK]

Yes, nice to see some wind-loading calcs. I've was quite frightened seeing my dishes flapping about like a hanky in the gales last year. Whatever you do, make it strong!

I got the impression before that you shed was quite sturdy. If it's quite flimsy, strapping it to the pole could be it's downfall. Literally!

Some guy-wires to the top might be better. Getting your dish/motor as low as possible is the first priority

[russzero]

that was a kool story. so what happened? did it bring joy or gloom? .. no this isnt a script from batman .. also .. why cant i see the pics? .. ive noticed this before. (im only getting a picture in my head .. & not on the screen) is something up with the IE browser? .. wouldnt put it past it.
the wind calc was very mind bogling. got me thinking that our back wall could cave in any min now!!! blimey .. ha ha

[Robbo]

Russ,
Any pictures that were in this thread have gone I'm afraid, after Satellite Help merged with Techwatch. I have not been able to retrieve them from the old forum unfortunately, just tried.

Robbo

[russzero]

ok .. im always interested in being nosey .. lookin at the pics .. but hey .. some u win! thnx

[Yorks]

If you haven't already, have a look in here.

http://www.techwatch.co.uk/forums/sa...o-gallery.html

Yorks