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Thread: Anyone built a zip line for the kids...??

  1. #11
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    Jan 2003
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    On the Oil Coast,USA
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    Quote Originally Posted by DR View Post
    This afternoon we cobbled together a test zip line. Looks promising so far.

    My favorite hardware store had a 28' rem of galvanized, 1/4" cable for 4 bucks (rated 1400 pounds). That was enough length to do testing stretched between 16' spaced trees with come-along for tensioning. The kids had already scrounged a 2" diameter stamped, no bearing, Home Depot pulley.

    The pulley is a problem, the cable has a bumpy surface because of the twisted wire construction so under load with no bearing and small diameter it doesn't zip along the cable freely. Tomorrow off to look for a better pulley.
    You need something with a 3-4" diameter sheave with a sealed ball bearing in it.The sides of the block need some UHMW liners to resist the cable wearing into them.
    I just need one more tool,just one!

  2. #12
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    Sep 2012
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    Australia
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    Food for thought - a 30-something mother riding a well established backyard zipline with multiple braking devices a few suburbs away from me, broke her neck and will never walk again after hitting a tree when the brakes failed last weekend.

    Now I don't presume to say that constructing your own zipline is unsafe and you shouldn't do it, but given you're asking questions a second-year mechanical engineering undergrad should be able to answer, and you intend to allow your children to use such a device, perhaps it might be a good idea to evaluate whether such a device is realistically within your capabilities?

  3. #13
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    May 2006
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    East Sussex UK
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    I set one up when the kids were young from a tree in the garden. They had great fun, but one night I had a nightmare when one of them had had a terrible accident with it - illogical as dreams are - the rope was caught round his neck.

    First thing in the morning I took it down !

  4. #14
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    Sep 2007
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    North Carolina
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    I'll second or third that if they will get up some speed on this that you put in some method of slowing them down before they hit the stop. Plenty of videos on YouTube of hitting the stop and sending the person flying. Something mechanically like an arresting cable on a carrier.

    Steve

  5. #15
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    Jan 2003
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    Quote Originally Posted by Sun God View Post
    .................................................. ..............................................


    Now I don't presume to say that constructing your own zipline is unsafe and you shouldn't do it, but given you're asking questions a second-year mechanical engineering undergrad should be able to answer, and you intend to allow your children to use such a device, perhaps it might be a good idea to evaluate whether such a device is realistically within your capabilities?

    I appreciate your concerns about my engineering capabilities. Let me assure you the concerns I have as to cable size have nothing to do with any thing that was covered in my mechanical engineering curriculum.

    My cable concerns are related to cable stiffness, weight, ease of coiling and how much the kids can help with installation/takedown. The zip line will not be in my yard, the kids are my grand kids and it'll be in their yard. Their parents don't want it to be so permanent that the kids can't play a role in handling the hardware. As it is with 1/4" cable it was all the 5 year old could do was get up the ladder a bit and re-position the harness on a tree (any stiffer cable and she would have been out of luck).

    The pulley was a bad choice, but it was something the kids had found by themselves and were proud of that. We had to actually try it for the kids to see it wasn't a good choice. Likewise they came up with a way to use a dog harness as a sling type seat, that didn't work well either. Live and learn.

  6. #16
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    Jan 2013
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    Michigan
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    I bought an entire 828 foot spool of 1/2" elevator wire rope at auction for $40. Unfortunately it is not galvanized, so ziplines are pretty much excluded. Haven't decided what to do with it yet. I'm sure if I sell it then I will immediately need it to capture Godzilla or similar.

  7. #17
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    Mar 2008
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    Barrie, Ontario, Canada
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    I can't (or won't) advise you on cable diameter, but 5/16" diameter seems about right.--Now it's time for a story. I had a cottage up in the Muskoka Lakes region of Ontario, and I always remember this. There was a high cliff on one side of the lake, (about 80 feet) and about 200 or 300 feet off shore there was a small island with one big tree on it. Some enterprising kids (I assume it was kids) had rigged a zip line from the top of the cliff out to the top of the tree on the island. At the sag in the lowest part of the cable, it was about eight or ten feet off the water. Their pulley was the front rim off a small bicycle, still attached to the forks (inverted) and the handlebars were what you hung onto. I never seen anybody actually use the thing, but I remember thinking that you'd have to be a pretty damn ballsy kid to take a trip on it.
    Brian Rupnow

  8. #18
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    Mar 2004
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    northern indiana, usa
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    BudB

  9. #19
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    Oct 2014
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    There are many different types of cable construction all with different degrees of flexibility. A stiff cable, 1x7 or 1x19, ( one strand made up of 7 or 19 wires) will be stiff and is made for applications where it doesn't need to flex. Like guy wires. Other more flexible constructions such as 7x7 or 7x19 (or finer) are made to flex, 7x7 less than 7x19. The more and finer the strands and wires in the strands the more the rope will tolerate flexing. Running over a pulley or sheave is flexing. The larger the dia. of the sheave the better and it varies with the dia. of the wire rope and it's construction. The groove in the sheavae should be just slightly larger in radius than the radius of the cable. For 5/16 cable a guess would be .005" to .010". There are too many variables here to make recommendations. Try looking at the Loos and Co. web site for sheave diameters, groove specifications, etc.

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