Clevis or quick link?
January 17, 2011 6:34 PM   Subscribe

What is the ideal way to attach steel cable to an eye bolt?

I'm building a suspension-style treehouse, and I don't have a lot of construction experience. I've noticed that both clevises and quick links are cheap and provide tons of strength. Is there a reason to use one or the other? (And if not, why are there two surviving designs to do the same thing?) Or maybe there's some other kind of connection that would be better?

For bonus points, aim me at any good on-line resources for working with wire cable/building suspended structures. My searches keep getting overwhelmed by shopping sites.

(Other advice, comments and suggestions would be super great, as long as they're not, "Don't do it unless you're an expert.")
posted by nathan v to Home & Garden (15 answers total) 6 users marked this as a favorite
Best answer: Quick links aren't ideal for something like this that is more of an installation. You want something more permanent. They are good for temporary things because they are easy to open and close but not as strong as other options. Also you don't want something that could possibly work its way undone. The better way of doing a more permanent installation is running the cable through the eye bolt with a thimble and secure it with cable clamps (also called crosby clamps I think by some people) or a crimp a sleeve on there or both I guess. There are lots of other ways of doing something like this - look at shackles for a strong, permanent, but removable option.
posted by Fred Wesley at 6:55 PM on January 17, 2011 [2 favorites]

Cable Clamps
posted by HuronBob at 6:55 PM on January 17, 2011 [2 favorites]

Cable and thimble, with wire rope clips.

Install your eye bolt. Run the cable though, install the thimble. Clamp a short end 8"-12" length from the eyebolt (depends on cable thickness - I am just guessing here what you'll be using). U-bolt goes on the short end side, the saddle goes on the load bearing side of the cable. Use two wire rope clips.

Install turnbuckles to adjust tension.

Clevises have specific applications, not suited for basic cabling I think. The quick links are not for permanent construction. Besides, you still need an eye and thimble, so just attach the cable to the eye (or with a turnbuckle) and skip the clevis/quick link idea.

Tree bracing uses "tree grips". These are good for trees, but I would not use them in an application where you have a live load. They work like Chinese handcuffs, best under constant tension or little load.
posted by Xoebe at 6:55 PM on January 17, 2011 [4 favorites]

This is what I mean by a shackle.
posted by Fred Wesley at 6:57 PM on January 17, 2011

Xoebe - much clearer than my rambling thoughts.
posted by Fred Wesley at 6:59 PM on January 17, 2011

I know riggers and safety should be your utmost concern, all 3 folks have provided good answers, the thimble is must for wear, the clamps for proper seating etc.

You should be very aware of the weight load any cable system can handle including the clamps.

In safe construction overkill never hurts.
posted by Max Power at 7:03 PM on January 17, 2011

Response by poster: Thank you all for the helpful advice.

I am thimbling my cable terminations (which are created with clamps). I am overbuilding significantly, in terms of weight ratings vs expected load.

While I could build my eyes directly into my eye bolts, there are a couple of reasons I'd rather not. First is that it's pretty much impossible to spin a lag with a thimbled cabled, and trying to clamp/terminate a cable while hugging a ladder twenty feet above the ground doesn't strike me as a lot of fun. Second is that it seems smart to build easy points of adjustment/replacement into my system.

What exactly is the difference between a shackle and a clevis? Wikipedia has pages for each, that don't reference each other, and even share a picture.
posted by nathan v at 7:19 PM on January 17, 2011

First is that it's pretty much impossible to spin a lag with a thimbled cabled

this is where a turnbuckle comes into play, it allows you to increase or decrease tension without spinning the lag bolt or the cable.
posted by Fred Wesley at 7:29 PM on January 17, 2011 [1 favorite]

some different types of turnbuckles

The third one in has a pin which you could attach to the eye of the bolt. Then you could put a shackle through the thimble at the end of your cable and and attach it to the other end of the turnbuckle.
posted by Fred Wesley at 7:32 PM on January 17, 2011

My brain seems to be working in fits and starts so the information continues to trickle in...
This is just a general tip but as you said other advice or comments is welcome - when using shackles is not necessary to tighten them with a wrench, just finger tight is fine. Then you want to mouse them. Mousing wire is a thin piece of wire that you loop through the hole on the pin of the shackle, then around the bell and just kind of crimp it off. It prevents it from ever spinning open. Thats all it needs.
posted by Fred Wesley at 7:39 PM on January 17, 2011


Also, when reading that it refers to the pin of a shackle as the clevis pin. So perhaps a clevis and a shackle are one in the same? Just different names. There are many different styles so come could be called by a different name.
posted by Fred Wesley at 7:41 PM on January 17, 2011

From wikipeda: The combination of a simple clevis fitted with a pin is commonly called a shackle, although a clevis and pin is only one of the many forms a shackle may take.
posted by d4nj450n at 7:49 PM on January 17, 2011

Best answer: Just to add a little on what others have said:
A quick link, rated appropriately, would most likely be fine, and better than a clevis; the clevis has a threaded part on one of the load-bearing ends, where the quick link has the loads at the ends of the oval with no chance for moving the threaded closure.
I believe three cable clamps per termination is what's recommended, spaced at four times the cable diameter, I think. Certainly thimbles are important.
Turnbuckles are probably what you want, but make sure they're rated adequately. Everything you use should be rated with a safe working load.

If you're building a treehouse, then in order to overbuild, DO NOT USE LAGS. Use through eyebolts with washers. But also be aware, every bit of hardware you put into a tree creates a wound, and with it, an entry point for decay. The species of tree you're installing in can really make a difference. Where you install in a tree makes a difference, as well as whether or not you're putting it between two (or more) trees or stems, because they will move independently and exert forces on the structure. If it's between stems, create movable joints. Don't put any cables girthed around branches or stems, it will girdle the bark and kill tissue. Try not to create a bunch of pressure points on the bark, because the pressure will kill the tissue beneath, especially as the tree expands with annual growth. You say you're building it suspension-style, which I think can be great, but you've also got to keep it from banging against tissue. You might stabilize it somehow against the tree with minimal touching. I've thought about a long lag to keep space and room for growth.

As far as building tips, instead of searching for treehouse techniques, look for "rope course" techniques, because besides the carpentry of the house, most of what you're doing would use those techniques.
posted by Red Loop at 8:18 PM on January 17, 2011

Best answer: nathan v writes "What exactly is the difference between a shackle and a clevis? Wikipedia has pages for each, that don't reference each other, and even share a picture."

Varies from place to place and among trades. To me a clevis is a piece of metal with a hole in it designed to accept the clevis pin of a shackle. Undoubtedly that definition will grate on someone like the clip vs magazine grates on gun enthusiasts.

Don't use quick links for anything load bearing. A (WLL rated) shackle, a coupling link should be used instead or (and here is where my naming convention breaks down) a double clevis which is like two shackles back to back. Anything used for overhead lifting or to support humans needs to be constructed with a safe working load 10X greater than expected supported weight. Also be aware that when you have more than two cables supporting any particular load that each cable needs to be able to support half the load as the other cables often are only steading the load bearing cables.

Also your eyes (whether screw or bolted) should be forged and not just looped.

Wire rope clips generally need to be spaced at 6 cable diameter intervals. Sometimes only two clips are required but it only costs money to use three clips at each loop back. Also the nuts on wire rope clips need to be properly torqued (IE: with a torque wrench) gradually tightening the nuts sort of like torquing down a head. The first clip should be as close to the thimble as possible and the dead end of the cable should be looped back such that the cable extends one saddle width past the last clip. Clips should be retorqued after you perform a maximum expected load test on the completed cable. And if it was me I'd make sure I was spending the cash on forged clips.
posted by Mitheral at 7:17 AM on January 18, 2011

Lots of good advice here already. Thimbles to protect the cable, use cable clips or nico press sleeves. For something permanent I always go with nico, hell even when I'm rigging for theater once I've got the scenery where I want it I nico it.

If you use clips make sure you have them oriented correctly never saddle a dead horse. Also Crosby Group has lots of information on their web site on how to use them.

Shackles are great, just remember as pointed out above, to mouse them. Also look for domestic Chicago or Crosby Shackles, avoid Chinese shackles. They use a lower safety factor in rating their rigging gear.

I can get you more rigging resources later if you need, but I'm leaving the office here shortly. I'll check back in on this thread.
posted by MrBobaFett at 10:56 AM on January 18, 2011

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