You will still need to preheat the CI before attempting to weld the CI. If not, you'll end up with cracks in the CI. JB Weld, works great... for certain things. I'm with Bj with this one. I wouldn't recommend using it to mount a router with.
Cast Iron is tricky and very difficult to work with. You'd be better off "brazing", (using a brass rod to weld), any pieces than trying to weld with a stick or wire welder.
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