Show me a little tail, please

The crimp oval on the left is done with a bit of the cable exposed above the metal, as it should be.

On the right, we have one that came-up a bit short.  To get full strength out of the crimp it must be compressed down around ALL of the cables.

Copper crimp ovals are preferred over aluminum ovals due to reports of cracks and splits in the softer aluminum.  Check your cable terminations regularly to see that they holding-up and were done correctly.

Common tool manufacturers for compression fittings are:

• Loos Company (www.loosnaples.com)
• Nicopress (National Telephone Supply Company) (www.nicopress.com)

Also notice the split link used to connect the chain back to itself.  This device is not rated for overhead lifting and, therefore, should not be used for stage rigging.

[Wire] Rope Terminations at Arbors

This picture shows a single purchase cast iron arbor top plate. The wire ropes are not supported by thimbles allowing them to deform and separate strands under load. Additionally, only one wire rope clip was used for termination, in lieu of the required minimum of two. Some of the "Crosby" clips (u-bolt cable clips) are installed backwards with the dead (unloaded) end of the cable run under the saddle (Remember: "Never saddle a dead horse").

The fiber hauling line does not have a thimble either, which acts to buffer the abrasive casting finish against the rope surface. Here is a picture of an arbor bottom plate with a plastic rope thimble (they are also available as a metal type):

This is a very old wire guided arbor with extended eye bolts for attachments (again, no thimbles to reduce the point-load on the rope bending point). You can also see that the top plate is tilted showing that the arbor has been racked and is skewed diagonally.

Here is the top of a double-width arbor (carries two stacks of weight). Again, no thimbles. It appears that the installer tied a clove hitch and then terminated the cable with just one wire rope clip. I don't know where the loose nut (partially hidden) that was laying on top of the arbor top plate came from . . .

And here is a the top of a new arbor that is properly terminated. Note that the load lines can be disconnected without cutting the cable. This makes them much easier to work on and replace if necessary. You can also see how the wire rope cables are not deformed as they bend around the thimble. Also of note is the safety wire (mousing) on the screw-pin shackle to keep it from coming apart. It's unknown why the front-most line was attached with a shackle when the other lines were looped around a through-bolt.

Wire rope cable termination gone wrong - very wrong

(Sigh) What can I say that this picture doesn't? Obviously, the proper way to terminate a wire rope was not in this person's skill set. Good intentions mean little if someone gets injured due to a rigging failure.

• Know your load.
• Know your cable strength.
• Know how to apply a safety (design) factor for live loads vs static loads.
• Know the efficiency (derating) of the termination method (Crosby's are different than Nicopress).
• Know how to install a cable thimble.
• Know how to terminate it for maximum safe load carrying capacity.

If you use cable clips ("Crosby's"):

• Know how to install them ("Never saddle a dead horse" means don't install the forged cable grip over the unloaded tail of the cable).
• Know how many you need.
• Know the spacing required.
• Know the torque of the bolts/nuts and use a torque wrench to achieve it.

If you use crimp-on sleeves ("Nicopress"):

• Know how to install them.
• Know how many you need.
• Know the spacing required.
• Know which axis of the compression oval is to be crushed (crimped).
• Know how to check and adjust the crimping tool so the die properly siezes the compression oval.
• Use a Go / No-Go gauge to check your finished crimps.

{Photo courtesy of 'Curiousbrandt' on Flicker}