Machines and Powered Equipment
Machines and Powered Equipment tests safe setup and operation of workshop machines, especially the pedestal drill and centre lathe, together with speed selection and guards.
Drilling
Clamp work to the drill table or in a machine vice; never hold it by hand. Centre-punch first, then drill a pilot hole for large diameters. Use cutting fluid for steel. Spindle speed depends on material and drill diameter: N = 1000S/(pi x D), where S is cutting speed in m/min. For HSS in mild steel, S is about 25 m/min. An 8 mm drill therefore runs at about 1000 x 25 / (3.14 x 8), which is about 995 r/min, rounded to the nearest available speed. Remove the chuck key before switching on.
Lathe work
The work is held in a chuck or between centres, and the tool is set at centre height. For facing and turning, keep hands clear, do not wear gloves, tie back hair, and never measure or clear swarf while the spindle turns. A roughing cut removes more metal; a finishing cut gives accuracy and finish.
Other machines
Power hacksaw: clamp the work, select the blade pitch, and let the machine complete the cut. Grinder: stand to one side when starting, keep the tool rest close to the wheel, and wear goggles. Sheet-metal shear: keep fingers clear of the blades and do not cut hardened steel.
Worked example: speed choice
A 10 mm drill in aluminium, with S about 60 m/min, gives N = 1000 x 60 / (3.14 x 10), about 1910 r/min. Aluminium cuts faster than steel, so a higher speed is correct; too slow a speed causes rubbing and a poor hole.
Traps
Forgetting the chuck key, wearing gloves at the lathe, using a blunt drill or forcing a drill are common mark-losers. Do not change speed while a machine runs unless it is designed for it, and never leave a machine running unattended.