A 3/8" (9.52 mm) IC triangular, uncoated insert with a 1/64" (.8 mm) cutting radius. Gives the best finish results when machining precision counter bores often machined in diesel engine blocks. The 1/64" (.8 mm) radius should be used when machining to a step where the mating part requires a smaller radius to eliminate an interference problem. If you are machining a long bore where the spindle must be extended towards the limits of its travel or if a long stub bar is being used, the 1/64" (.8 mm) radius will minimize the possibility of chatter. A feed rate of .002" - .005" (.05 mm - .12 mm) should be used to obtain a typical surface finish. When machining large counter bores typically found in Cummins or Cat Blocks, a feed rate of .002 - .004/rev. (.05 mm - .1 mm/rev) should be used.
When cutting nodular, ductile, or compacted graphite cast iron the speed should be in the 200 – 400 S.F.P.M. area – 300 RPM on a 4" (100 mm) diameter bore. Nodular, ductile, or compacted graphite cast iron is found most often in high performance engine blocks or sleeves. When cutting these tuff cast irons it is best to use a feed rate of between .006" and .010" (.15 mm and .25 mm) per revolution.
