I85PREP
⌘ K
Tamil Nadu HSE First Year Basic Mechanical Engineering study materials
Tamil Nadu HSE First Year Basic Mechanical Engineering study resources

Tamil Nadu HSE First Year Basic Mechanical Engineering: Hand Tools and Work Bench Operations

Tamil Nadu HSE First Year Basic Mechanical Engineering · Work through your exam, one topic at a time.

All guide sections

Hand Tools and Work Bench Operations

Hand tools and work bench operations covers the tools you select for a bench job, the way each is held, and the sequence that turns a raw bar into a finished part. Questions typically ask you to name a tool from its description, choose a file grade or hacksaw blade, or arrange operations in order.

Holding and striking

The bench vice grips the work; soft jaws (lead or fibre) protect finished surfaces. Hammers: ball peen for riveting and centre punching, cross peen and straight peen for stretching in smithy. Never use a hammer with a loose head, and hold it near the end of the handle.

Cutting tools

  • Cold chisels: flat for chipping and cutting sheet, cross-cut for keyways and grooves, half-round for curved grooves, diamond for squaring corners.
  • Files: the cut is single (one diagonal row) or double (two crossing rows, faster); a rasp is for wood. Grades from coarsest to finest: rough, bastard, second cut, smooth, dead smooth. Always fit a handle, clean with a file card, and never rub backwards on hard steel.
  • Hacksaw: 300 mm blade, teeth pointing forward. 14–18 teeth per inch remove soft thick sections; 24–32 TPI suit thin tube and hard metal so the teeth do not snag.

Sequence

Mark with scriber and steel rule or vernier, punch the centre, hold in the vice, then cut, file, drill and tap. Leave filing allowance after sawing.

Worked example

Cut a 20 mm mild-steel rod to length. Choose a 300 mm hacksaw with an 18 TPI blade, because mild steel is soft and the section is thick; a fine 32 TPI blade would clog. Clamp the rod with about 20 mm projecting, start the cut with a light forward stroke at a slight angle to form a groove, then use the full blade length at about 40–60 strokes per minute, with pressure on the forward stroke only. Rubbing on the return stroke dulls the teeth.

Traps

Teeth fitted backwards; no handle on a file, so the tang can pierce the wrist; chipping without goggles; filing across the vice jaws instead of along the work; using a bastard file where a smooth finish is specified.