This is my first post, and I'm a little slow on the uptake as I just read this cable welding info. So, I thought I'd add my experience welding cable:
I only weld cable that is 1"+ in dia. It seems that smaller than that, the wires often burn prior to coming to a welding temp. It is important to completely mig weld the ends to keep the cable from fraying. Most larger cable usually has grease inside. This is not a problem as it can be burned out in a less than welding heat. After burning the grease, I take the cable to the slack tub for a quick dunk, then wire brush the scale. I open the cable slightly and flux all around. After that, back into the forge at a less than welding heat, then out to the vise for tightening with a pipe wrench that has a handle welded on the opposite side of the stock handle. As mentioned, sometimes more than one heat is necessary.
I slowly bring the cable up to welding temp letting it soak and trying not to burn the wires. This is interspersed with several trips to the flux. When it's time to weld, I go straight to the power hammer and lightly forge a flat on one side, then work the other equally, ultimately squaring the cable. The cable is brushed, fluxed again, brought to a welding temp and taken to the hammer. This time I round the cable by breaking the edges, then slowly rolling and pulling the cable out toward me. I'm sure most smiths know how to do this. Then it's just a matter of cleaning up the round. I've found that this method seems to help eliminate inclusions.
After forging it flat to about 3/8" thick, I cut, stack, and re-weld, sometimes several times.
It seems to me that cable is not a good element for blades as if it is on a cutting edge, it will probably be the least noble of the other steels used in the blade, and when etched, will be somewhat ragged. It does give a nice textural look though.
I'll try to post some pics of cable and my super duper flux formula.
John