In my line of work I have opportunity to learn how to weld journals .Parts will come in that need repair and the the journals will need to welded and turned down to size.When they get welded there can be no pits on the finished diameter.I know you will get a laugh but all we have is a 140 Hobart mig for the job.The parts vary from a .5 in. to3.0 in . in diameter.The guy who regulary welds these parts gets it done flawlessly and I am trying to pick up the skill also.He does it with no preheat.A little more to the story we have a Miller 250 mig at my disposal and that is the machine I would like to use. What are some suggestions that would help? I do have for my use an induction coil for preheat . We normally use a circular pattern lapping over the previous weld in a upside down j.On bigger diameters I have experimented with a straight weld but that can sometimes bend the part. I know I am rambling a bit and I will try to post pictures for clarity. Thanks for all your help.