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Aluminium Tube - Reduction of weight.

  flycatcher1 19:11 08 Mar 2014

I am trying to reduce the weight of an aluminium tube, 3mm thick, 4.5 inches in diameter and 4.4 metres long. It is necessary that the tube will not twist or bend and my first thoughts are to bore innumerable holes or make slits.

The tube is for a Conservatory sunshade, the last one was wooden and lasted 25 years but I hope that this one will see me out. I am 84 and can easily lift the tube but would prefer to reduce the weight.

Any help would be appreciated.

  carver 19:28 08 Mar 2014

Drilling round holes will reduce the weight but make sure that any holes are not opposite each other or you will make a weak point in that area.

Just don't make any slits as this will have a tendency to promote twisting because of the length you have.

For what you are going to save in weight it's an awful lot of work.

Far better to buy a better grade of aluminium then you can have a thinner wall section.

  carver 19:30 08 Mar 2014

this enter link description here will give you an idea about different types.

  bumpkin 19:39 08 Mar 2014

If you can easily lift it and it is a sunshade which you are hardly ever likely to need does it matter.

  flycatcher1 19:43 08 Mar 2014

carver Thanks for your prompt response.

My suppliers were not able to obtain a thinner ally at the required diameter and length. It is already sitting in the garage with the stub axle ends ready for insertion.

My fittings will take the present weight but I would prefer a reduction. I had better get on with it with the temperature expected to be 15C tomorrow.

  morddwyd 07:35 09 Mar 2014

As already suggested, I would go for a better grade of aluminium in the first pace, perhaps aircraft grade, where weight costs money ongoing!

Any holes, even one, will set up inherent weakness and the actual drilling/cutting will initiate stress fields.

If you conservatory is anything like mine metal can get too hot to touch in high summer (hollow laugh!)and the constant expansion and contraction will exacerbate these weaknesses and stresses.

  Aitchbee 12:26 09 Mar 2014

If the long tube consisted of 2 or 3 interlinking, shorter cylindrical sections similar to the metallic extensions on some vacuum cleaners then this might make it easier and lighter for transporting and storage purposes.

PS. My birdfeeding stations work on the same principle.

  bumpkin 12:44 09 Mar 2014

It seems a rather pointless exercise, reducing the weight of something that you can easily lift anyway.

  carver 13:19 09 Mar 2014

*bumpkin *You haven't seen flycatcher1 enter link description here have you

  Forum Editor 13:35 09 Mar 2014

By the time you have drilled enough holes to appreciably reduce the weight you will have created a tube that is too weak for the job it has to do.

You could cut slits, but the effect would be the same.

  flycatcher1 09:58 10 Mar 2014

carver Very droll, if only!

bumpkin I can lift it but managing to fix it on to the conservatory roof is another matter.

morddwyd I flew in some aircraft that had holes, a friend of mine got into trouble for always wearing a raincoat when airborne. One aircraft is at Cosford.

Following advice I am going ahead with the project sans holes.

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