How to Construct a Zip Line

Zip lines can be fun, but they should be carefully constructed for safety.

Zip lines can be amazingly fun for individuals of all ages, but they come with a certain amount of risk. Some of these risks can be managed with intelligent design and construction of the line itself; some cannot. Adult supervision and the installation of a safety surface beneath the zip line are the most important ways to mitigate the risk of injury. That said, zip lines are relatively easy to install anywhere with sturdy trees. Avoid taking shortcuts during installation, and you'll ensure the best experience possible for any riders.

Things You'll Need

• 1/2-inch diameter steel cable
• 3/4-inch steel turnbuckle
• (2) 5/8-inch eye bolts (three inches longer than the diameter of the trees you select)
• 5/8-inch steel washers
• Rubber mulch
• Steel cable clamps (1000-pound rated or more)
• Zip line handlebars
• Pulley (1000-pound rated or more)

Instructions

1. Choose the anchor trees. They need to be sturdy, mature trees (minimum 15-inch diameter or more) that don't show signs of rot or disease. They can be as far apart as you wish, but you'll have to clear a 6-foot (or wider) path between them.

2. Tie a length of colored string or rope to each tree at the height you want to put the zip line. Use this as an aid while clearing overhanging branches, nearby trees, and other obstacles.

3. Take one eye bolt and a power drill to one of your anchor trees. Attach the 5/8-inch extension bit to the drill and make a level hole straight through the center of the tree. Place the 5/8-inch washer over the hole on the back side of the tree and trace a circle around it. Remove the washer and pry away the bark within the circle.

4. Use a mallet to drive the eye bolt through the hole so that the eye faces the other anchor tree. On the back side of the tree, slide the washer over the bolt and then screw on the bolt. Tighten the bolt as much as possible without crushing the tree wood.

5. Repeat steps 3 and 4 for the other anchor tree.

6. Install the turnbuckle to the lower zip line eye bolt. Make sure the piece has not yet been tightened.

7. Take one end of your length of steel cable and loop it through the eye bolt in the higher anchor tree. You'll want at least three feet of cable to double back on itself after passing through the eye bolt. Use your cable clamps according to the manufacturer's instructions to fasten the cable to the eye bolt.

8. Repeat step 7 at the lower anchor tree. The cable will actually attach to the ring end of the turnbuckle here, since the turnbuckle is already attached to the eye bolt. Hand tighten and fasten with cable clamps. Trim away any extra cable.

9. Use a large wrench to turn the turnbuckle bolt, tightening the line progressively. Carefully test the run at slow speeds to make sure the cable is holding weight appropriately. If it sags, tighten the turnbuckle more.

10. Mount the zip line trolley bar to the cable, making sure to follow all of the manufacturer's instructions to prevent the trolley from "hopping" off the line during use.

11. Spread a safety material like rubber or finely chipped wood mulch in a six-foot wide path along the zip line. It should be at least 6 to 12 inches deep to provide padding in the event of a crash.

References

• Dangerously Fun: Zip Line
• Outdoor Fun Store: How I Put Up Our Zip Line