Hello All, I build model steam engines from casting kits, the castings are un machined, and I work to drawings. Some kit suppliers cut their tolerances pretty fine making a bit of an adventure, now I do not know much about the different types of cast iron but this stuff leaves me looking like a coal miner. If you put in a search for ''corncrake'' my Photobucket album should appear, the large 10'' cast iron flywheel had a skin on it that had to be under cut with an angle grinder, very hard to get through, but turned fine otherwise. I used a combination of Glanze insert tool and tipped tools...how would you guys approach machining castings like these. All the best for now, John.