Now that I have a few more minutes of time I can go into some more detail.
things done wrong:
1) didn’t use the tool correctly to compress the fitting. As mentioned before it looks like the person didn’t compress the outside, or circumference of the fitting, but rather used the space between two openings of the jaws of the tool to “press” the fitting between the two parts of the wire rope.
The way a swage fitting works is by getting a certain amount of surface area of the fitting into contact with the wire rope at a certain pressure. This is achieved by using the correct size tool to compress the fitting to a pre-determined size, verified by using what is known as a go-nogo guage. This is why one manufacturer might say 4 compressions for a certain size fitting, and another might say 3. Let’s say tool 1 has a jaw .25” wide, tool 2 has a jaw .50” wide, and the fitting requires 1” of compressed surface area along the fitting. Tool 1 would require 4 compressions to get the required 1” of surface area needed, while tool 2 would only need 2 compressions.
2) Using 2 fittings for an eye. A properly used fitting to form an eye is 100% efficient, meaning that it does not reduce the strength of the wire rope at all. That means that a single fitting compressed properly on a wire rope to form an eye using a 5:1 df (the standard for slings, while for running rigging it’s 8:1) will only have a maximum of 20% of its capacity used. Adding a second fitting does not gain you any further capacity or security. Now the minutia. When you form an eye the wire rope is coming out of the fitting at a angle off the centerline of the fitting. This angle adds friction and thus increases the capacity of the fitting. On a lap splice the wire rope is coming out parallel to the centerline of the fitting and there is no inclrease in friction and hence no increase in capacity, which is why you use 2 fittings for a lap splice.
Now back to your regularly scheduled thread.
Regards,
Ethan
