Cutting Speeds. Determine the spindle speed for turning, milling, drilling, and reaming with these charts and cutting speed calculators. Turning speeds are adjusted to the feed rate of the mini lathe (0.004/rev.), a depth of cut of 0.040, and a tool life of 180 minutes. 6061-T6, 5000, 6000, and 7000 series. 6061-T6, 5000, 6000, and 7000 series.