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Ryan Allen
PostPosted: Sun Apr 30, 2017 9:21 am 
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Can I use long AN3 bolts (that would go all the way through the tube) to attach the end pieces to the elevator push pull tube instead of rivets?


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James Grahn
PostPosted: Sun Apr 30, 2017 10:16 am 
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Ryan Allen
PostPosted: Mon May 01, 2017 6:58 am 
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As a point learning here, what's the issue?


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James Grahn
PostPosted: Mon May 01, 2017 9:11 am 
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I'm not a structures engineer, but I know the rivets have to pinch each side of the tube. A bolt straight through will not do that.
Any structures guys out there want to sing out?
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ljkrume
PostPosted: Mon May 01, 2017 3:02 pm 
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Just like he says. Rivets swell to fill the hole too. Ensures tight connections and also removes worry about things coming loose... Les


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Ryan Allen
PostPosted: Mon May 01, 2017 5:52 pm 
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James Grahn wrote:
I'm not a structures engineer, but I know the rivets have to pinch each side of the tube. A bolt straight through will not do that.
Any structures guys out there want to sing out?
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Oh, makes sense. I hadn't considered that. I was only considering the end pieces being pulled out of the tube by a push/pull force. Thanks.


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jrevens
PostPosted: Tue May 02, 2017 12:05 am 
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With bolts the shear forces are concentrated in fewer areas (holes) than with the multiple rivets, as per design. Even an AN-3 bolt would probably have plenty of shear strength, but the issue is that the relatively thin aluminum will have much less. It's better to distribute the properly sized fasteners around the perimeter of the structure, and those rivets will also weigh less than even a single bolt.

Correction - I was thinking about the machined "cone" that I made for one end of my tube, that I attached with blind rivets. With the end fittings as per John's design, my honest thought is that AN-3 bolts could probably have adequate edge hole distance, and the "forked" end thick and stiff enough, to probably be fine structurally, but again - more weight. I wouldn't recommend it. It's always best to go "as designed" with important structural parts like this.

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