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| This is fine if tou need to add a tiny amount of tension to a belt, but it will kill you if you use it to zip line. |
With my dad's zip line out of commission, there was a danger vacuum in our yard that I was longing to fill. The tragedy of the zip line being cut down because that girl broke her neck fresh on my mind I decided to build my own. I was going to build it from the top of our fort, which was fourteen feet above the ground, to a tree that was about 60 feet away. I was not as versed in the ways of mechanical engineering as I should have been to attempt a project like this.
I thought to myself what are the basics? What is essential to a zip line? How would Frank Loyd Wright design this? Just kidding on that last one, Wright is a hack. I knew this you need a wire, you need a high place, you need a lower place and a pulley of some sort. I just put that stuff together and I would have a zip line.
For my cable, I got a copper wire from a roll of stranded 12 gauge copper wire. Copper wire is generally more known more for its conductivity then its load bearing capacity, which is none. It is the type you would find in standard household wiring. Perfect if you need to run a light switch or a socket but instant death in the load bearing capacity I was using it for. I affixed one end to the tree above the top of my fort and the other to the tree at the alleged landing site.
For the pulley, I used a belt tensioner salvaged from a whirlpool dryer. Once again way off the mark when it came to the required capacity. Did I give it a test run with a weight more or less the same as my own? No, no and heck no. A dry run, in retrospect, may have been the more sound course of action, but then this story would not have a punch line. rejecting the timid path of a more sensible engineer, I decided to jump right into it, literally.
My little brother was at the bottom watching me and I jumped off, putting all my weight on the undersized cable and pulley all at once. I plummeted to the ground. I don't think that wire provided even a nanosecond's worth of resistance toward breaking my fall. I went straight down flat onto my bottom knocking the wind out of myself. I jumped up and rubbed my butt and said, 'Ow, ow, ow, ow, ow.'
As soon as I gathered my thoughts I told Matt not to tell mom, which is the main concern of all great engineers. Do you think the Wright brothers mom knew what they were up to? No way, she would have nipped that nonsense in the bud. All great engineers don't tell mom.
I figured that this spectacular, unmitigated and even catastrophic failure was a sign that I should stop building zip lines. Resigning myself to walking around on the ground like regular poor people.
