Dealing with cast iron / stress?

[claudef]

Many years ago (20), I was in England at a machine rebuilder. They had an old large planer and were machining the ways for a machine they were rebuilding. My first observation was, if they are so good a machine rebuilding, why would they not have a nice gantry mill for this type of machining. After voicing my opinion they explained that any type of milling operation naturally induced stress into the material surface. Planers, on the other hand, remove a small amount of material on the full length of the part in minuscule steps and does not induce stress. Take this for what it’s worth but if you have access to a planner, I would plane the surfaces then do your scraping.
Claude