Engineering Graphics & Elements of ME
From transcript: 20ME110 Elements of Mechanical Engineering (C) · 20ME220 Engineering Graphics and Design (B)
Cheat sheet
Formulas
Definitions
- Orthographic projection
- Parallel projectors ⊥ to plane — multi-view engineering drawings
- Isometric
- Axonometric with equal foreshortening ~30° axes — pictorial
- Hidden line
- Dashed edge not visible in that view
- Centerline
- Axis of symmetry / path of hole — long-short dash
- Dimensioning
- Size + location from datums; avoid closed chains
- Tolerance
- Allowed variation; bilateral/unilateral/limit
- GD&T
- Geometric tolerances controlling form/orientation/location/runout
- BOM
- Bill of materials — part balloons on assembly drawing
- Section view
- Cut plane reveals internal features
Topic-wise short notes
Projections & dimensioning
- Six principal views; usually 2–3 suffice with sections.
- Auxiliary views for true size of inclined faces.
- Development of surfaces for sheet metal (patterns).
- Fits: hole-basis H7/g6 etc. — clearance/transition/interference.
- Surface finish symbols and machining allowances on drawings.
Elements of mechanical engineering
- Energy conversion overview: IC engines, turbines, boilers, refrigerators.
- Basic machine elements: shafts, bearings, couplings, belts, gears — recognition.
- Material selection cues from application (strength, corrosion, cost, fab).
Orthographic & section views
- Full, half, offset, broken-out, revolved sections — pick clarity.
- Aligned sections for spokes/ribs conventions.
- Detail views for small features; broken views for long parts.
Drawings as contracts
- Ambiguity → scrap/rework — drawings are legal/manufacturing contracts.
- Revision block, ECO trail, material & heat-treat notes matter.
- Ballooned assemblies must match BOM item numbers.
Exam traps & quick notes
- Readable drawings beat pretty ones — dimension from datums.
- Elements of ME: intro to thermodynamics, fluid machines, power plants, IC engines at survey level.
- Bridge to CAD: same projection rules in SolidWorks drawing sheets.
- Projection symbol in title block settles first vs third angle disputes.
- Dimension to finished surfaces/datums used in manufacturing.
- Don’t dimension hidden lines if a visible view exists.
- Section preferred over hidden-line spaghetti for interiors.
- CAD drawings still follow the same projection & dimensioning rules.
Comprehensive notes
Projections & dimensioning
Hidden lines, centerlines, cutting planes. Dimensioning standards avoid redundancy; use baseline or ordinate for CNC.
External: Engineering Drawing basics (NPTEL) ↗ ISO GPS overview ↗
Elements of mechanical engineering
Survey of energy conversion, boilers, turbines, pumps, refrigeration cycle overview — vocabulary for later thermo/fluids courses.
External: Britannica Heat engine ↗
Orthographic & section views
First-angle vs third-angle; India commonly first-angle. Hidden lines, centerlines, cutting planes. Dimension from datums; avoid redundant chains that fight CNC.
External: NPTEL ↗ Engineering Toolbox ↗
Drawings as contracts
Title block, tolerances, notes, BOM balloons. Ambiguous drawings create scrap. Bridge to CAD: same projection rules in SolidWorks drawing sheets.
External: NPTEL ↗ Engineering Toolbox ↗
Interview Q&A for this subject
Q: First-angle vs third-angle?
A: Relative placement of views vs object; symbol in title block — always check which standard the company uses.
External: ASQ / quality ↗ MIT OCW ↗