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Once the hole has been drilled, pull the drill straight out until the twist drill is completely withdrawn from the hole before shutting off the motor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 Decimal-fraction equivalent sizes
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 ” (A) and increase to ” (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 Twist drills also come in various lengths
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 Power tool safety precautions 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