I'm making a steel bar fence and on a whim purchased these post caps that are made of cast iron. http://www.kingmetals.com/Pages/Page5-6.htmlI'm wondering if anyone knows if MIG would work to weld them onto the 2" square .0625" steel post. I have been migging the whole thing so far and would like to continue the same way but an not sure of the results. I also have a buzz box with some nickel rod but is it necessary? If a preheat is in order, what temp and are the crayons necessary? How would a fence installer normally get these things on? Thanks in advance.