A new ₹350 carbide insert is supposed to give you 30 to 60 minutes of cutting time per edge across four edges, which is two to four hours of useful machining for a hundred-and-fifty-rupee per-edge cost. On a well-set-up lathe, that is exactly what you get. On the average MSME lathe in central India,

Walk through a typical MSME machine shop in central India (Jabalpur, Indore, Pithampur, Nagpur, Raipur) and you will find a tool drawer with thirty different inserts in twenty different boxes, most of them part-used, none of them clearly catalogued, and at least half of them used on materials they w