At $15 each for the machined kingpin end, I don't even think I would mess around cutting up a stock axle. Just buy the ends and get a tube and go to it
. You'll spend more time cleaning up the junk you cut off and on consumables than it is worth
I've got a lathe, and by the time you get the material and spend the time making them it is pretty much a wash if you ask me to just buying those ends from EZBucket.
Good thread, now I know how I'm going to do it. I was considering cutting up a truck I beam but now I'm not even going to bother. New ends + new tube = nice welds and nice results.