Cots and Bunks Question

Anything to do with mechanical, construction etc

Postby bobhenry » Tue Aug 02, 2011 11:39 am

The bending would be deminished because you now have a tensioned member. The wood fiber in the pole is now tensioned much like a guitar string. You have transfered the load somewhat into the walls themselves.
I agree that the load could tear out the pole support sides as the pin is also being side loaded and is attempting to bend with the pole so it could lever the fibers in the support block and split it like a wood wedge in a log.

Always something to think about huh?
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Postby StandUpGuy » Tue Aug 02, 2011 11:49 am

bobhenry wrote:The bending would be deminished because you now have a tensioned member. The wood fiber in the pole is now tensioned much like a guitar string. You have transfered the load somewhat into the walls themselves.
I agree that the load could tear out the pole support sides as the pin is also being side loaded and is attempting to bend with the pole so it could lever the fibers in the support block and split it like a wood wedge in a log.

Always something to think about huh?


a clothes line stretched to a bent nail on a tree is a tensioned member too until the nail bends.

The wooden pole is a lever and the edge of the "cradle" is a fulcrum. From the middle of the pole where it is bending to the edge of the cradle is a long distance and from the edge of the cradle to the pin is a short distance. The lever action of the pole on the little pin is tremendous. If there is not a lot of bending of the pole then there will not be a lot of force on the pin. If there is a lot of pole bending the the lever is being pushed down and there will be a lot of force on the pin to bend.
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Postby bobhenry » Tue Aug 02, 2011 1:00 pm

yep !

That' kinda what I said !
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Postby StandUpGuy » Tue Aug 02, 2011 3:51 pm

The photo of the two children on the one cot shows there is some bowing of the wooden pole. It does not seem excessive however. If that is all the bowing it will do then what he has going should be fine. It would seem no increase of pole diameter or reinforcing or pins is necessary.
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Postby Deryk the Pirate » Tue Aug 02, 2011 6:02 pm

Forget round....a pair of 2x3's could have the edges rounded a bit and would easily support a kid's weight
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Postby CarlLaFong » Tue Aug 02, 2011 6:57 pm

StandUpGuy wrote:Well I fail to see how the pins would stop the poles from bowing. I would think the bowing would still happen and simply bend the pins and or tear the hole the pins are dropped into on the cradle.

You're talking about a child, not a hippopotamus. If you drill the cradles and the poles and use 7/16 or 3/8 steel pins, they will not bend. Period. They will also not tear out of the sides unless the cradles are made of some cheepo thin material. I never cease to be amazed, when given a simple effective solution to a problem, the number of naysayers that will emerge and predict doom and death and suggest various expensive, heavy, cumbersome and Rube Goldberg solutions. To those folks I say, "Fine, whatever works for you."
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Postby StandUpGuy » Tue Aug 02, 2011 7:13 pm

CarlLaFong wrote:
StandUpGuy wrote:Well I fail to see how the pins would stop the poles from bowing. I would think the bowing would still happen and simply bend the pins and or tear the hole the pins are dropped into on the cradle.

You're talking about a child, not a hippopotamus. If you drill the cradles and the poles and use 7/16 or 3/8 steel pins, they will not bend. Period. They will also not tear out of the sides unless the cradles are made of some cheepo thin material. I never cease to be amazed, when given a simple effective solution to a problem, the number of naysayers that will emerge and predict doom and death and suggest various expensive, heavy, cumbersome and Rube Goldberg solutions. To those folks I say, "Fine, whatever works for you."
Your pin idea is a fine suggestion.
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Postby S. Heisley » Tue Aug 02, 2011 7:16 pm

This thread has developed a life of its own! :noyes: :dead:

I'm outa here!
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Postby StandUpGuy » Tue Aug 02, 2011 7:20 pm

Deryk the Pirate wrote:Forget round....a pair of 2x3's could have the edges rounded a bit and would easily support a kid's weight
Yep that would do it. I am thinking the OP is going to see how it goes as is because he already has the cradles complete and the poles purchased and cut. He could always later switch it out.
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Postby CarlLaFong » Tue Aug 02, 2011 8:50 pm

[/quote]Your pin idea is a fine suggestion.[/quote]
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Postby bobhenry » Wed Aug 03, 2011 8:42 am

And no one mentioned the possibility of a fire !

:laughter:
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Postby StandUpGuy » Wed Aug 03, 2011 12:00 pm

bobhenry wrote:And no one mentioned the possibility of a fire !

:laughter:


That would only happen if it does not have trailer brakes... but you know that. 8)
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Postby boatyardgirl » Wed Aug 10, 2011 7:21 pm

WOW I learned exactly what I am going to do here! I did a search just for canvas bunks and here was the answer :worship:

I love the idea of the pin and the 2 by 3 (square end)
BUT my daughter is 100 lbs( & 17 years old) so I think I will go with 2 by 4s set in pins and a square cut in the cradle (wont roll out). I will be using heavy duty outdoor grade canvas set with pounded grommets. I hope to be able to pick up the edge roll it up and fasten it to the wall when we dont need it. If I thought I needed it I could" hang" the edges with wire. Thoughts? Amanda
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Postby StandUpGuy » Wed Aug 10, 2011 7:39 pm

boatyardgirl wrote:WOW I learned exactly what I am going to do here! I did a search just for canvas bunks and here was the answer :worship:

I love the idea of the pin and the 2 by 3 (square end)
BUT my daughter is 100 lbs( & 17 years old) so I think I will go with 2 by 4s set in pins and a square cut in the cradle (wont roll out). I will be using heavy duty outdoor grade canvas set with pounded grommets. I hope to be able to pick up the edge roll it up and fasten it to the wall when we dont need it. If I thought I needed it I could" hang" the edges with wire. Thoughts? Amanda
Sounds like a plan.
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Postby S. Heisley » Thu Aug 25, 2011 10:13 am

[quote="S. Heisley"] ...It is just a couple inches shy of 5' long. The diameter of that pole is 1 ¼â€
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