Conventional Machine Tool Setup and Operation (Milling, Turning, Grinding, Drilling)
This domain covers setup and operation of milling machines, lathes, surface and cylindrical grinders, and drill presses. The exam tests speeds and feeds, workholding, cutter and wheel selection, and the geometric checks that decide whether a part comes out square and to size.
Milling
Up (conventional) milling is the default on machines with backlash; climb (down) milling gives a better finish and longer cutter life but only on machines with backlash eliminators or ball screws. Calculate spindle speed from RPM = (3.82 × SFM) ÷ D, where D is cutter diameter in inches, then feed from chip load per tooth. Set the cutter as close to the spindle nose as possible to limit deflection; use an arbor support for slitting saws.
Turning
Set spindle speed from the same formula based on work diameter. Roughing depth of cut is limited by rigidity, not by the insert; finishing passes of 0.25–0.5 mm control size and finish. A three-jaw chuck self-centres but has low repeatability; a four-jaw chuck with a dial indicator is used when concentricity matters. Thread cutting requires correct gearing and engagement of the half-nut on the thread dial.
Grinding
Wheel selection balances grit, grade and bond. A softer grade (later letter) suits hard materials and small contact areas; a harder grade suits soft materials and wide contact. Dress the wheel to open the face and restore form; balance wheels above 150 mm. Spark-out - passing with no infeed - removes deflection and improves finish. Flood coolant prevents burning and cracking.
Drilling
Clamp work rather than holding it by hand, start with a centre drill, and reduce feed as the drill breaks through. Peck drilling clears chips in deep holes.
Worked example
A 20 mm (0.787 in) HSS end mill machines mild steel at 90 SFM. RPM = (3.82 × 90) ÷ 0.787 = 437 rpm. With a chip load of 0.10 mm/tooth and 4 teeth, feed = 0.10 × 4 × 437 = 175 mm/min. Reasoning: speed comes from cutter and work material, feed from chip load and tooth count; lowering either without reason wastes time, raising speed burns the cutter.
Traps
Climb milling on a worn leadscrew; exceeding the wheel's rated speed; leaving the chuck key in the chuck; measuring a turned diameter with the spindle running; and not accounting for cutter deflection on deep slots.