Build Zip Line with Steel Tubing: 500lb Load Bearing

[vagajdbond]

I am looking at building a zip line in my back yard and using steel tubing as my end anchors with the following specifications

75' span / support 500lbs at the center / 1/4" steel cable / anchoring the tubing into a 8"x6' masonry wall and encasing it is concrete with an additional 4' of tubing exposed.

I was considering 2x2x.250 but I am starting to believe that might be to small for this. Would 3x3x.375 be able to handle this type of load? If not what size and type (round or square) would handle this. Appreciate any advise on this. - JD

 

[Grinkle]

I haven't ever thought of this kind of design before. Why will you use tubing? Why not attach an eyebolt to the masonry wall and then loop the line through the eyebolt, fold it back on itself perhaps between 12 and 24 inches and use a crimp type fastening to hold the loop made by the cable?

If I picture your design correctly, you are asking if the tubing will bend along the horizontal due to the downward load and resulting moment between the end of the tubing and the point at which the tubing goes into the wall? If this is a concern, why not just make the tubing flush with the wall? Why are you exposing 4' of tubing?

I am probably missing all sorts of design considerations, never looked very closely at zip line attachments.

 

[vagajdbond]

Grinkle - Wow that was a quick response thanks! The wall is only 6' high so I need to extend it up to cover the slope needed to get the trolley moving. That being said I did plan on using eyebolts with the fold back you mentioned but I will be attaching them to the tubing at approximately 10' on one side and 8' at the other. So my concern is the downward load on the tubing and what sizing I would need to support approx 500lbs. Not that I would ever have that much on the line but I would like to beef it up.

 

[Grinkle]

Ah- the tubing is vertically extended - I get it. Use the thickest tubing you can find. The cost won't differ by much. Gross overdesign is the way to go with this project, imo.

 

[berkeman]

We don't discuss dangerous projects here on the PF. You shouldn't be asking for advice like this on the Internet. Please try to find a local professional resource to help you with designing and building your Zipline. Thread is done.