8.3 Hand & Power Tools: Identification, Uses & Fasteners

Hand & Power Tools: Identification, Uses & Fasteners

Mastery of shop tools, hardware, thread cutting, and mechanical fasteners is a foundational skill for automotive technicians, military mechanical specialists, and craftsman engineers. Using the correct tool for the specific material and job ensures work quality, prevents fastener damage, and eliminates serious shop injuries.

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Striking, Chiseling & Punching Tools

Striking Tools (Hammers & Mallets)

• Ball-Peen Hammer (Machinist's Hammer): Features a flat face on one side for driving punches and cold chisels, and a hemispherical ball end (peen) on the other for rounding over metal rivets and shaping sheet metal.
• Claw Hammer: Designed for woodworking. The curved claw is used to pull nails out of timber.
• Sledgehammer: Heavy two-handed hammer (4 to 16 lbs) used for heavy demolition and driving stakes.
• Rubber / Soft-Faced Mallet & Dead-Blow Hammer: Soft-faced hammers (rubber, plastic, brass, or lead) deliver firm impact force without marring delicate machined surfaces. A dead-blow hammer contains internal steel shot that moves forward on impact, absorbing bounce-back vibration and delivering solid kinetic force.

Chisels & Punches

• Cold Chisels: Hardened steel cutting tools struck with a ball-peen hammer to shear or cut metal.
  • Flat Cold Chisel: Used to cut rivets, split frozen nuts, and cut sheet metal.
  • Cape Chisel: Has a narrow blade designed for cutting keyways and narrow grooves.
  • Diamond-Point Chisel: Used for cleaning out square corners and V-grooves.
• Punches: Cylindrical steel tools struck to mark locations or drive pins.
  • Center Punch: Features a heavy 90° conical point. Struck to create a deep dimple in metal, preventing drill bits from "walking" across the surface.
  • Prick Punch: Features a sharp 30° to 60° point used for fine layout marking.
  • Pin Punch (Drift Punch): Has a straight cylindrical shaft used to drive out roll pins, dowel pins, and rivets after they have been loosened.

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Holding, Clamping & Pliers Identification

• Combination (Slip-Joint) Pliers: Feature an adjustable two-position pivot pin allowing the jaws to open wider for grasping different-sized objects.
• Needle-Nose Pliers: Long, tapered jaws designed for grasping tiny electronic components or reaching into narrow enclosures.
• Diagonal Cutting Pliers ("Dikes"): Angled cutting jaws designed exclusively for shearing electrical wire, cotter pins, and small fasteners.
• Locking Pliers (Vise-Grips): Feature an adjustable screw mechanism in the handle that toggles over-center, locking the serrated jaws tightly onto workpieces with high clamping force.
• Tongue-and-Groove Pliers (Channellocks): Adjustable arc-joint pliers with multiple parallel grooves, providing wide jaw capacity for gripping large pipe fittings and plumbing components.
• Snap-Ring Pliers: Specialized tips designed to expand external retaining rings or compress internal retaining rings.

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Cutting, Filing & Threading Tools

Hacksaws & Tooth Selection

A hacksaw consists of a metal frame holding a thin steel blade under tension. Blades cut on the forward stroke (teeth must point forward away from the handle).

Files & Filing Techniques

Files feature sharp parallel teeth used to remove small amounts of metal. They are designated by shape (flat, round/rat-tail, half-round, triangular/three-square) and tooth coarseness:

1. Rough Cut / Bastard Cut: Coarse teeth for rapid metal removal.
2. Second Cut: Medium tooth spacing for general shaping.
3. Smooth Cut: Fine teeth for producing smooth surface finishes.

Shop Safety Rule: Never use a file without a securely attached wooden or plastic handle! The exposed sharp file tang can puncture the palm or wrist if the file slips.

Taps & Dies (Thread Cutting)

• Taps: Cut internal threads inside a pre-drilled hole.
  • Taper Tap: Features 7 to 10 chamfered starting threads at the tip. Used to start thread cutting easily.
  • Plug Tap: Features 3 to 5 chamfered threads. General-purpose tap used after starting with a taper tap.
  • Bottoming Tap: Features only 1 to 1.5 chamfered threads. Designed to cut full-depth usable threads all the way to the bottom of a blind hole.
• Dies: Circular or hexagonal hardened steel tools used to cut external threads onto cylindrical rods, studs, or pipe ends.

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Wrenches, Sockets & Precision Torque Application

• Open-End Wrench: Has U-shaped openings on both ends set at a 15° angle. Contacts fastener heads on two flat sides. Fast to position, but can slip under high torque.
• Box-End Wrench: Encloses the fastener head completely with a 6-point or 12-point opening. Applies force without slipping.
• Combination Wrench: Has an open-end opening on one side and a box-end opening of the exact same size on the other.
• Socket Wrenches & Ratchets: Sockets attach to ratchet handles via square drive studs (1/4", 3/8", 1/2", 3/4" drive sizes).
  • 6-Point Sockets: Contact the flat faces of hex bolts. Recommended for high-torque applications to prevent rounding bolt corners.
  • 12-Point Sockets: Easier to slip onto bolt heads in cramped quarter-turn spaces, but contact near fragile corners.
• Torque Wrench: Precision measuring tool used to tighten threaded fasteners to exact manufacturer torque specifications (measured in foot-pounds [ft-lbs], inch-pounds [in-lbs], or Newton-meters [N·m]). Available in clicker, beam, and digital electronic types.

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Fasteners, Hardware & Thread Specifications

Threaded fasteners are classified by diameter, thread pitch, length, and strength grade.

Imperial (SAE) vs. Metric Fastener Designations

• Imperial (SAE) Example (3/8" - 16 UNC x 1-1/2"):
  • 3/8" = Nominal bolt shank diameter.
  • 16 = Thread pitch expressed as threads per inch (TPI).
  • UNC = Unified National Coarse thread series (UNF = Fine thread).
  • 1-1/2" = Overall length under the bolt head.
• Metric Example (M8 x 1.25 x 30):
  • M8 = Nominal diameter in millimeters (8 mm).
  • 1.25 = Thread pitch expressed as distance between adjacent threads in millimeters (1.25 mm per thread).
  • 30 = Length under head in millimeters (30 mm).

Fastener Strength Grade Identification

Formula for SAE Grade: Count the radial lines on the bolt head and add 2. (e.g., $3 \text{ lines} + 2 = \text{Grade 5}$). (e.g., $6 \text{ lines} + 2 = \text{Grade 8}$).

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Summary Checklist & Study Tips

• Ball-peen hammer = metalwork; Center punch = 90° drill locating dimple.
• Hacksaws cut on the forward stroke; maintain at least 3 teeth in contact with metal.
• Bottoming taps cut threads to the bottom of blind holes.
• 6-point sockets prevent rounding high-torque bolt heads.
• SAE Grade = Radial lines + 2 (3 lines = Grade 5; 6 lines = Grade 8).