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trampoline Before redesign
Before

The Eccentric Trampoline Project

Robert Walsh

trampoline After redesign
After

This project improves an old round trampoline by replacing the existing pipe legs with a wood platform that supports the frame and prevents distortion. The frame actually rests on the wood framework to prevent horizontal distortion. The wood framework also holds the frame perfectly round. The end result is a very solid trampoline with a pleasantly smooth demeanor.



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Why do this?

Within the first year of owning my trampoline, it became damage from the stresses of jumping on it. Springs were overstretched, welds broke, and the frame as a whole became quite deformed. Every jump caused the frame to buckle in and out. As the frame joints became looser, the shape of the frame became more distorted. This caused uneven stresses on the springs causing them to fail. Further , the distorted springs were damaging the connecting loops on the mat which was causing distortion in the mat as well.

Trampoline Flex Frame distortion from jumping was distroying my trampoline

This modification eliminated all frame flex and gaurantees the shape of the trampoline will stay true. It also made the trampoline very quite and rock solid. Every jump is smooth, even, and predictable. I started this project to fix my trampoline and improve upon some inherent design flaws. The improvement to my trampoline was beyond my expectation.

Trampoline Project

1. The photo to the left shows the project near completion. It may look complex but is really quite simple. It is just 16 wood squares bolted together to form a circle. I wanted the height of the trampoline lower than stock. So, I dug a pit in the center of the frame.

Trampoline project

2. Each section of the frame requires 2 legs cut square and 2 horizontal supports cut at an angle. I decided to lower the height of my trampoline by about a foot. So, the legs are each 20 inches long. The horizontal supports are 33 inches at the long edge and cut at a 11.25 degree angle. To compute the legth of the support multiple pi by the diameter of the trampoline and divide by 16. Or, (3.1415 x 168 inches)/16 = 32.9858 inches. The angle is computed by dividing the number of degrees in a circle by the number of edges that require an angled cut. Or, 360 degrees / 32 = 11.25 degrees.

Trampoline project

3. Using 3 inch wood screws, I screwed the sections together. It is hard to tell from the picture but the wide edge of the legs are flush with the angled edge of the support. I also used wood glue at the end of every leg to add a bit of strength.

Trampoline Project

4. The finished frame section has 2 screws and some glue at every joint. I prefer joining wood with wood instead of metal because metal eventually will rust but screws are so much faster. I cut all the angles with a Dewalt compound miter saw. This is a fast and precise way to cut angles.

Trampoline Project

5. Here are four of the sections. Just 12 more to make then they can be bolted together!

Trampoline Project

6. I want the top of the frame to be perfectly level and the outer edge to be perfectly round. To get the least amount of deviation, I clamped the top edge flush with a 2x6. The legs were held flush with a clamps as well.

Trampoline Project

7. With the clamps in place, I drilled a 3/8 inch hole about 2 inches from each end of the leg. Then I put a 3/8 x 3 inch bolt in each hole and tightened it down with a bolt and washer before removing the clamps. After getting a few sections bolted together I could see my project taking shape!

Trampoline Project

8. After bolting all 16 sections together, I cut off the legs of my trampoline with a hack saw and placed the legless frame and mat on the wood structure. It was a perfect fit!

Trampoline Project

9. I positioned the trampoline on the wood frame so that the place where the steels pipes are joined together is centered on each wood section. I then screwed a short 1x1 to the wood section so that the outer edge of the steel frame is flush with the outer edge of the wood frame. Doing this ensure that the frame will stay round by preventing it from flexing inward.

Trampoline Project

1 0 . I orginally intended to use clamps to hold the mat down. However, went with bungee cords instead because they allow the mat to be removed without tools. It also prevents unnecessary drilling into the wood supports.

Trampoline Project

1 1 . The finished project works great and looks cool!

Copyright © 2005, Robert Walsh, All Rights reserved.