I got my hypertherm 1650 G3 the other day and decided to take it for a spin. Once I had it all set up (I am using a trailer generator for the 3 phase) The nearest piece of scrap near me was some 4" used cast iron from a sewer replacement we just finished. I know cast iron has a high carbon content and can be hard to weld but figured my g3 had the extra power to cut it. Well it did not cut it, it just got hot and sparked. I tried 50 amps and 80 but it made no difference. Now this was rusty ugly been buried in the ground for 50 years pipe. I reached over grabbed a piece of 1/2" plate steel and it buzzed right through it. My question is there a special procedure or tip that does make cutting cast pipe a possibility? I tried it on 2 different pipes and cut plate steel in between with no machine changes so I know the machine was right. Maybe a bad ground since the pipe was so ugly and pitted and rusty?