Rant: my feed and speed chart was off by 20 percent and a guy in Dayton showed me why
I ran 4140 steel at the same numbers for 6 months because the chart on the wall said 800 rpm and 12 ipm, and I never checked it against anything else. A machinist in Dayton named Ray pulled up the insert maker's online calculator and showed me the wall chart was printed for a different coating. My tool life went from 2 hours a part to 5, and I felt pretty dumb about the scrap pile. Anyone else ever find out their shop chart was just plain outdated?