Swingset Engineering

BigBody79

BigBody79

Well-Known Member
Joined
Mar 30, 2005
Location
Lumberton
I have a older municipal swingset that I got some time last year. It is about 3 sections long. Shown in the photo is only two sections. I have enough materials to make it one more section. However, I would like to only do what is shown in the photo and eliminate the middle support.

The top tube is 2.5" Pipe which has an ID of 2.0". So, a piece of 2" tubing will fit inside of it. I am thinking that if I get a piece of tubing to go inside of it and weld it all up it will be strong enough.

I have a place very local that has a piece of .053 at 10' that caught my eye. But, what wall thickness should I go to make this thing strong enough? .053, .065, .083, .095, .120, .250!,

The ladder in the picture is about 8ft for reference.

swing set.JPG
 
I think I'd leave it like it is. That's a pretty long span on just 2.5" pipe, regardless of what is put together with. You get a couple of kids swinging on it and it will be bouncing like hell if it dosent go ahead and horseshoe on you.
 
Why eliminate the middle support? If it's just to gain space for another swing, instead I'd just slightly extend both of those and squeeze in 3 across.
Rubbin' is Racin'.
 
That's a long span, and sleeving that long span is still going to make it a long span. If you internally sleeve it, you're adding material closer to the centroid where the bending stress is the lowest so the additional material isn't adding nearly as much stiffness as if you were increasing the diameter of the outer tubing. You also don't add as much buckling resistance as you would have with a single piece of tubing with the combined wall thickness, because the two concentric pieces of tubing are only attached at the weld joints and will have relative motion in bending.
You're also changing the tension and compression in the outer supports (all 3 for each side) because the added deflection of the longer span will change the length between the supports.

Yes, you can make that long span stiff/strong enough, but I don't think the proper way is to add material to the inside of an already small diameter pipe.

Why do you want to remove the center support? The way it is now is safe, and works. I'm no structural engineer, but my intuition says this is a pretty sketchy idea.
 
We need some RobbyBobby the flat biller killer action here.
Sorry @Fabrik8 you aint gonna get this, lol.

We need a Dadgum Mohawk welded on with meth smoke, that'll hold them younguns. Middle fangers!

Actually.... if you wanted to eliminate the middle support a Mohawk would work.
 
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You need something with a larger diameter to get sufficient stiffness to handle that span. Like @Fabrik8 said, adding stuff inside the tube does almost nothing for the strength. Obviously you've decided against it at this point, which is wise. Without doing any math, my gut says you need at least 5" tubing to have enough strength, and 6" for enough stiffness to match. Or use like a 12" diameter chunk of timber. I recommend oak. Here's a 5 seater I did for a friend:
10358978_10101154790931808_4974960233772158362_o.jpg

10348661_10101155457830338_911742209418415739_o.jpg
 
jeepinmatt said:
You need something with a larger diameter to get sufficient stiffness to handle that span. Like @Fabrik8 said, adding stuff inside the tube does almost nothing for the strength. Obviously you've decided against it at this point, which is wise. Without doing any math, my gut says you need at least 5" tubing to have enough strength, and 6" for enough stiffness to match. Or use like a 12" diameter chunk of timber. I recommend oak. Here's a 5 seater I did for a friend:
View attachment 266355
View attachment 266356
Click to expand...

Is that oak? Looks like poplar on my wee little cell phone screen. I like that idea a lot. I may do one of these for the kids soon.
 
josh m said:
Is that oak? Looks like poplar on my wee little cell phone screen. I like that idea a lot. I may do one of these for the kids soon.
Click to expand...
You are correct, it is poplar. Not my first choice, but I had just cut it down when a good friend asked me where to find a swingset that would hold all 5 of his kids. I said hey man, I've got a deal for you! :D
 
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