On 6/20/2011 1:35 PM, Dennis M wrote:
In , "Stormin Mormon"
wrote:

Maybe make a letter H, with a very long center
|--------------------|
between the trees, out of two by sixes. Lag bolt them on, so
you can trim the boards as the trees grow. Hang the swing
from that.

Or use two big screw eyes, and a cable. But, since the trees
are only about five feet apart, the boards are a better
idea.

I'm sort of hesitant to make a direct connection between the trees at the
top with something like a 2 x 6 because these are really tall trees and
I've noticed they can sway slightly in a very strong wind. I think just
dropping a chain to the seat using eye bolts would work better.

You don't need a hard connection on both ends, or even one of them,
really. Lag some blocks to the tree, and rest a floating box frame beam
that encircles the trunk on the blocks. Unless trees really sway, it
doesn't even have to go all the way around- a frame like a section of
ladder would work. As a kid, we did floating supports for multi-limb
treehouses like that. Tree could still flex with no problem, and the
treehouse never got overstressed. For ease of construction, a couple
long 2x6s or 2x8s in parallel, with cross-pieces to make them nice and
stiff, maybe slanted in alternating directions so they make box sections
but still drain well. Viewed from side, minus top and bottom edges,
since I suck at ASCII art: I / \ / \ / \ / \ I . Put the
beam together with deck screws, and hang swing from threaded rod run
through both sides of beam, or from short 2x6s run flat across the top.
As long as trees never sway so much that they spread enough to make
the beam fall off the blocks, it should hold up longer than you do.

Legal disclaimer- use at your own risk. If you kill somebody with this
design, remember what you paid for it. I am not an engineer or
architect, blah blah blah.

--
aem sends...