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View Full Version : OT: How to attach swing between two trees?



winchman
03-12-2009, 05:43 AM
I've always enjoyed swinging. I want to put a swing in my yard, but I don't want one with a bunch of pipes to mow around. There are no trees with a limb big enough at the right height.

However, there are two good-sized pine trees in a good place, and they're about eight feet apart. I know from experience, that the chains need to be parallel for the swing to move correctly, so I need to have a rigid support between the trees for the chains to hang from.

Since the trees move around a bit in a random manner when the wind blows, the connection between the trees and the support must accommodate some movement. I'm thinking the centers of the trees probably move around at least two inches in every direction at the height where the support needs to be.

The rigid support can be either metal pipe or a wood beam. I can attach stuff to the trees with several stainless steel lag screws.

I don't want the support itself to swing or rotate. All the swing motion will be handled with regular hangers, pendulums, and chains secured to the middle of the beam. See: http://byoplayground.com/hardware.html

So, what should the attachment that goes between the trees and the ends of the support look like?

Roger

Spin Doctor
03-12-2009, 07:47 AM
Yuo ever see the old cartoon about the tire swing. One picture how engineering designed it, one how safety/legal approved it, the final one what the customer wanted. Eight or ten pictures in all.

http://www.google.com/imgres?imgurl=http://www.jacobsen.no/anders/blog/archives/images/project-thumb.jpg&imgrefurl=http://www.jacobsen.no/anders/blog/archives/2004/05/17/the_tire_swing_cartoon.html&h=262&w=350&sz=23&tbnid=-0hK48WYPVRIZM::&tbnh=90&tbnw=120&prev=/images%3Fq%3Dtire%2Bswing%2Bcartoon&hl=en&usg=__7Dln3GWgo4bYOB2Q3WQx8vmJWxg=&ei=A-i4SaDmAYugtwe1osmhBg&sa=X&oi=image_result&resnum=3&ct=image&cd=1

Circlip
03-12-2009, 07:51 AM
Chain from each tree, seat between the two ends and then a joiner the same width of the seat higher up the chains to give a parallel drop. Like a letter Y but with two vertical legs spaced by the seat and the joiner.

Regards Ian.

BigBoy1
03-12-2009, 08:06 AM
If I understand the question, couldn't a horizontal support be placed between the trees, using the crotch of a large limb on each tree as the support point? Put something on the each end of the support bar to keep it from sliding out of the crotch such a round disk attached to each end of the support bar.

If there are not two limbs at the same height, use the limb crotch on one tree and mount a bracket to the limb that is lower one the second tree to make a support that will raise the level of the support point of the second tree.

This bracket could be something as simple a piece of wood with a semi-circular cut in the bottom and placed over the lower limb and the upper end of the piece of wood be the support for horizontal bar. Long metal (stainless steel) hose clamps couls be used to hold the wooden piece to the trunk of the tree.

Evan
03-12-2009, 08:12 AM
Careful you don't infringe this patent: Method of Swinging on a Swing (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6368227.PN.&OS=PN/6368227&RS=PN/6368227).

:D

Your Old Dog
03-12-2009, 08:52 AM
Make sure to make a small roof over top of the swing seat to catch all the pollen, needles, cones and bird do that falls. The kids will be sticking to your couch after a minute or so of swinging outside when the season is right. Our pine trees are messy as hell :D

digger_doug
03-12-2009, 09:53 AM
May I degress a bit?

2 pressure treated post's set in the ground where you want them.
No questions about strength/integrity, no questions about harming
the trees.

Get creative, and camoflauge the post's to look like tree's.

Doozer
03-12-2009, 12:17 PM
Cable the trees together with 1/2" steel cable. Slip on a 2 foot or so pipe for chain spread. Attach swing chains on the sides of the pipe. Swaying trees will NEVER break a 1/2" steel cable. Swing away.

--Doozer

Roy Andrews
03-12-2009, 12:57 PM
make a beam or pipe that will fit between the trees and then put a long u fork on each end that will easily fit around the tree with a little room for tree growth and movement. this will keep the tree from growing over and killing it where it encapsulates the beam. then cable or chain the beam up to the next branch/ crotch. on each side. the cables/ chains will grow into the tree but will not kill it in my experience. when younger i built a very large tree house this way and it still hangs to this day. although it is about 10' higher the last i checked. if you lag beams to the tree it will either push the lags out with growth or encapsulate the beam which will probably kill that section of the tree.

dp
03-12-2009, 01:48 PM
The rule of trees: Anything you affix to a tree will eventually become integrated into that tree.

http://www.museumofhoaxes.com/hoax/weblog/permalink/bicycle_eating_tree/

http://www.museumofhoaxes.com/hoax/weblog/permalink/motorcycle_eating_tree/

But - first you sling a yoke between trees. Make the swing with a rigid cross member at the top to keep the hangers parallel, and attach both hangers to a common point centered on the yoke. The swing will swing true so long as the length of both sides of the yoke are equal. You need to add a couple short stabilizers between the ends of the cross member and the yoke to keep the thing from spinning.

G-forces will cause the swing to dip closer to the ground unless the limbs are pretty substantial.

TreeSpike
06-21-2010, 02:24 PM
3/16 inch steel cable is cheap and will support 1/2 ton of weight, more than most branches.
Feed the cable through the top links in the swing chains and keep the chains from coming together by using 2 cable clamps inside the chains. Then
wrap the cable ends around two trees and secure with two cable clamps for each tree. You're done!

Your Old Dog
06-21-2010, 04:09 PM
If the trees are close enough, I'd use a 10foot pressure treated 4x4. I would chain each end to a tree. Each end of the 4x4 would have a hole drilled through it, a bolt would go through the chain, the 4x4, wrap around the tree just above a convenient branch and then bring the chain back to the other side of the 4x4 and slip it over the other end of the bolt and put a washer and nut on it. The swing would move normally but yet the trees would be allowed to move seperatly in high winds.

Evan
06-21-2010, 04:54 PM
A few more observations:

A swing is a pendulum. As such, for it to swing properly it must not be suspended by two parts with different periods. In other words, the best swing is one that has a pair of lines that swing from a rigid support.

Another important consideration is that it not be too tall or too short. Too tall is a common error and it makes the swing impossible to pump. The longer the lines are the slower the period of swing and the more that air resistance has a chance to slow down the swingee. No more than about 16 feet at the most and 12 to 14 may be better.

Safety: The swing should have a sand pit where those that like to jump off a swing will land. This will also save injury if somebody loses their grip and flies off the swing at altitude.

lynnl
06-21-2010, 09:34 PM
How big are the two pine trees?

I nailed a pressure treated 2 x 10 onto two sweetgums about 6 or 7 ft apart, and hung a kids' swing from the cantilevered end of the 2 x. It lasted at least 10 or 11 years, until I took it down last year. The trees were growing around the board and were holding it pretty securely on one end, but I could tell the nails were rusting away. ...and despite the PT, there was some decay in the board where the nails were, as if the tree sap hastened decay.

These trees were probably at least 16"-18" dia at breast height when I initially did it. I'm sure there's some relative motion between them due to swaying, but at the height involved it's probably very little. Most of the swaying is in the upper parts of the trees. The last 2 or 3 years the board warped a little and some of the nails loosened, but I'm confident the swaying never compromised the sturdiness of my arrangement.

(added) I probably had that board mounted about 12 ft above the ground, and it seemed just about right for that child's swing.

spkrman15
06-21-2010, 10:28 PM
Loved the Cartoon...too funny :) thanks for the laugh

Rob :)

tdmidget
06-21-2010, 11:01 PM
Not with pine trees. Any injury to the bark will bleed turpentine and make a mess to say nothing of the health of the trees.