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Aluminium tube battens - dimensions of spigot joint

  • 27 Sep 2017 07:36
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    Reply # 5281723 on 5271370
    Anonymous member

    I've done what Paul suggests and it has worked for me.  Rivet and glue the split inner tube.  The polyurethane glues seem pretty good in this application.
  • 25 Sep 2017 20:06
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    Reply # 5278794 on 5271370
    Anonymous member

    A simpler method that I have used before is to take a piece of the same diameter tube, of the suitable length, then cut a slot down the length of the joining section of just over twice the wall thickness. This gap can then be closed in a vice so the two tubes can be driven on, one at a time and riveted. 
  • 25 Sep 2017 18:09
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    Reply # 5278549 on 5271370
    Deleted user

    Many thanks for all your contributions. Regarding using engineering plastics such as Nylon 6.6 I had considered such options but after calculating relative strengths of plastic materials vs aluminium using yield strength values for the materials, I found aluminium tube (6082 -T6 grade) to be over 3.5 times as strong as the plastic spigot. I want the joint to be at least of equal strength so I think it would be unsuitable material in this case. 

    The discussion has given me another idea which is to have the solid rod spigot bored out, for at least part of its length to reduce weight. The wall thickness could be around 6mm without compromising the required strength of the spigot.

    Thanks again 

    frank
  • 23 Sep 2017 02:35
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    Reply # 5275532 on 5275460
    Anonymous member
    Annie Hill wrote:
    Darren Bos wrote:

     Perhaps I'm just being a weight-weenie....

    What about using one of these clever plastics, if you're bothered about the weight?
    Indeed. Nylon 6.6 is my current choice for conical hinges, so it will do equally well for a straight spigot, if you're not looking for articulation. Roughly half the weight of aluminium.
  • 22 Sep 2017 23:12
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    Reply # 5275460 on 5275124
    Anonymous member
    Darren Bos wrote:

     Perhaps I'm just being a weight-weenie....

    What about using one of these clever plastics, if you're bothered about the weight?
  • 22 Sep 2017 17:55
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    Reply # 5275124 on 5271370
    Anonymous member

    Agreed.  I had two alternative scenarios in mind.  First, if you lived in a location where you had access to tubing that can sleeve, such as available from some amateur radio sources.  The other case would be where you can mix pipe and tubing to find two sizes that nest neatly.  Even using heavy wall pipe for the plug and then turning it down seems like it would be more efficient than using a solid aluminum spigot.  Perhaps I'm just being a weight-weenie....
  • 21 Sep 2017 09:00
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    Reply # 5272853 on 5271370
    Anonymous member

    The problem, as ever, is finding two tubes that will sleeve neatly together. If you can, I suggest that it will be more weight-efficient to make a joining sleeve 300mm long for two tubes of 50mm diameter. A common scenario might be that you can find two tubes of which the larger is 0.250" greater in diameter than the smaller, and the wall thickness is 0.128" or 10SWG. This would require boring out to a sliding fit - possible for a length of sleeve of 300mm, working from each end; but would require a very large lathe to work on a long tube. All in all, the solid spigot, turned to fit, is the easier way to go.
  • 21 Sep 2017 05:05
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    Reply # 5272649 on 5271370
    Anonymous member

    Is it really necessary to use solid aluminum for the spigot?  If you were joining 50mm tube, you would need spigots of 300mm.  50 x 300mm is a pretty heavy chunk of aluminum and seems unnecessarily heavy.  Might the weight be better used by using a larger diameter tube on the forward section of the batten and sleeve a smaller diameter tube into the aft section?
  • 20 Sep 2017 15:58
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    Reply # 5271419 on 5271370
    Anonymous member

    Yes, three times the diameter of spigot within each tube, so a length of spigot of six times the diameter is satisfactory. It's the length I use for my double-cone hinges. 
  • 20 Sep 2017 15:29
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    Message # 5271370
    Deleted user

    I plan to join two lengths of tube together to make a batten of sufficient length. I aim to have a spigot made up from solid aluminium rod to create the joint. I have been searching web for advice as to how much overlap there should be within the tube sections but so far have been unable to find anything useful. 

    I think recall reading several years ago on the Yahoo hosted Junk Rig Group postings regarding construction of aluminium tube masts, by joining sections of progressively smaller diameter, that the overlap should be 3 times the tube diameter. Perhaps the same would apply to the design of the spigot joint?

    Has anyone practical / theoretical experience to offer on this matter?

    Many thanks

    frank 
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