POWER TOOLS

1. POWER TOOLS • Electric drills • Common electric drills have the capacity for drilling holes from 1/16” up to 3/4” in diameter • The size of an electric drill is usually determined by the capacity of it’s chuck • A 1/2” drill is equipped with a chuck that will take a twist drill 1/2” in diameter and no larger • Once the hole has been drilled, pull the drill straight out until the twist drill is completely withdrawn from the hole before shutting off the motor

2. POWER TOOLS • Drill press • Used for large and medium type work • The two common types are floor and bench-mounted • The size of a drill press is based on the maximum thickness of work it is capable of drilling (i.e. a 10” drill press can drill to the center of a 10” work piece)

3. POWER TOOLS • The drilling speeds may vary and may be as high as 5000 rpm • Proper drill press operation • Ensure the drill speed is correct for the material being drilled; normally, the harder the material, the higher the drill speed • Set the drill table at the proper height (about chest high) • Select a sharp bit of the correct size and center it in the drill chuck ensuring that no cutting edge of the twist drill is located in the chuck jaws

4. POWER TOOLS • Lower the drill bit to where the point will just clear the work and set the stop nuts at that position • After marking a pilot point with a center punch, attach the drill bit and secure the work • Apply power and lower the drill to the work • Once the bit begins to enter the material, raise the bit to recheck the alignment and adjust if necessary • Continue drilling until the bit is completely through the material, raise the bit, turn off the drill press and remove the work • Clean the drill press after use (do not remove shavings with your bare hands)

5. POWER TOOLS • Twist drills • Commonly called “drill bits” • Available in a wide range of sizes, shapes, and materials • Come in four size categories: • Fractional-inch sizes • These sizes begin at 1/64” and increase to 4” or more • Smaller bits increase in size by 64th’s • Mid sized bits increase in size by 32nd’s • Larger sized bits increase in size by 16th’S

6. POWER TOOLS • Wire-gauge numbers • These sizes run from No. 80 (smallest) to No. 1 (largest) • All sizes are less than 1/4” and correspond to standard wire sizes • Used where precise hole dimensions are required (i.e. tapping threads) • Decimal-fraction equivalent sizes • Begin at 0.2340” (A) and increase to 0.4062” (Z) • The largest size is smaller than 7/16” • Allow for sizes in between common fractional sizes • Used where exact hole dimensions are required

7. POWER TOOLS • Metric sizes • Use metric numbering system rather than decimal system • Allows for smaller sizes without complicated numbering or lettering system • There are many conversion charts showing how metric numbers compare to decimal • Twist drills also come in various lengths • Length will depend upon purpose • “screw machine” is the most common length and is what you will most likely use

8. POWER TOOLS • Common twist drill materials include: • High speed steel (HSS) • Suitable for drilling most materials • Excellent for metal cutting because it will stand up to high temperature • Carbon steel • Specially ground for drilling wood • Should not be used for metal because they tend to be more brittle and less flexible • May have special coatings to increase hardness or add self-lubricating properties

9. POWER TOOLS • Bench grinder • Used for grinding operations such as sharpening chisels, screwdrivers, drill bits, and punches • Usually has both a medium and fine-grain abrasive wheel • May also have a wire brushing wheel, buffing wheel or polishing wheel • Each wheel has an eye shield over the work area and a work rest in front of the wheels • The rest serves to stabilize the work held against it and should be kept about 1/8” from the wheel

10. POWER TOOLS • Bench grinder precautions • Before applying power to the grinder ensure the grinding wheels are securely attached to the shaft • Ensure the wheel is free of cracks and breaks • Ensure the grinder is mounted securely • Adjust the work rest to the proper angle for the work being done making sure the work cannot be placed between the work rest and the grinding wheel

11. POWER TOOLS • Bench grinder operation • Hold the work securely and do not push it against the wheel • Be sure the wheels are completely stopped before touching them • As often as possible, cool off the edges of the work being ground to prevent drawing of heat • Power tool safety precautions • Use personal protective equipment (PPE) such as eye and ear protection, gloves, and/or safety shoes • Dress properly for the occasion – no loose fitting clothing, long sleeves, ties, jewelry, etc • Attach work to a bench or vise if possible

12. POWER TOOLS • Never handle the cutting edge of any tool • Ensure power switches are turned off before plugging in a tool • Ensure that a portable tool has stopped running before laying it down • Never remove safety shields or disable safety features • Always ensure you have adequate room to work • Turn power off and unplug a tool to clear jams or clean debris from the work area • Ensure the area around the work area is free of oil, grease or other loose material that could cause poor footing