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CE En 112 Engineering Drawing with CAD Application

CE En 112 Engineering Drawing with CAD Application. Manual Drafting Supplement (Lecture C) Engineering Geometry and Construction. Lecture Outline . Engineering geometry (3.1, p.192) Coordinate spaces (3.3, p.194, we will refer to this one when we learn UCS), Geometric elements (3.4, p.200)

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CE En 112 Engineering Drawing with CAD Application

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  1. CE En 112 Engineering Drawing with CAD Application Manual Drafting Supplement (Lecture C) Engineering Geometry and Construction

  2. Lecture Outline • Engineering geometry (3.1, p.192) • Coordinate spaces (3.3, p.194, we will refer to this one when we learn UCS), • Geometric elements (3.4, p.200) • Points, lines, surfaces & arcs (3.5, p.202) • Conic curves (3.6, p.207) • Surfaces (3.10, p.218) will be covered as part of AutoCAD 3D lectures We cannot cover all materials in this chapter in one lecture. But, some of the definitions and concepts have been covered in your education up to this point (from elementary school). We place emphasis on quickly constructing necessary geometric elements. Terms you learn from this chapter have direct relevance to CAD.

  3. Engineering Geometry (Supp. 3.1) • Geometric construction: Act of constructing a geometry, especially using hand tools • Engineering geometry: Basic geometric elements and forms used in engineering design e.g., dividing a line Points, Lines, Surfaces, and Solids

  4. Geometric Elements (Supp. 3.4) • Manual drafting • AutoCAD

  5. Points, Lines, Surfaces, and Arcs (Supp. 3.5) • Point: Theoretical location that has neither width, height, nor depth and describes an exact location in space

  6. Line: Geometric primitive that has length and direction but not thickness May be straight, curved, or a combination Points, Lines, Surfaces, and Arcs (con’t)

  7. Points, Lines, Surfaces, and Arcs (con’t) • Tangencies: Exists when a straight line is in contact with a curve at a single point; that is, a line is tangent to a circle if it touches the circle at one and only one point

  8. Circles: Single curved surface primitive, all points of which are equidistant from one point, the center Points, Lines, Surfaces, and Arcs (con’t)

  9. Center Circumference Radius Chord Diameter Secant Arc Semicircle Minor arc Major arc Central angle Sector Quadrant Segment Tangent Points, Lines, Surfaces, and Arcs (con’t) • The elements of a circle are as follows (outlined in previous slide): • The slides that follow provide examples of manual drafting points, lines, surfaces, and mostly, arcs

  10. Points, Lines, Surfaces, and Arcs (con’t) Constructing arcs tangent to two lines

  11. Points, Lines, Surfaces, and Arcs (con’t) Constructing an arc tangent to a line and another arc

  12. Points, Lines, Circles, and Arcs (con’t) Constructing an arc tangent to two given arcs or circles

  13. Points, Lines, Circles, and Arcs (con’t) Constructing an arc tangent to two given arcs Please note that we should avoid this kind of reverse curve in highway alignment design.

  14. Points, Lines, Circles, and Arcs (con’t) Observe the signs carefully to place the center of a new circle that contacts the two existing circles. Constructing an arc tangent to a given arc

  15. Points, Lines, Circles, and Arcs (con’t) Constructing lines tangent to two circles or arcs, using a straightedge (a trial and error method)

  16. Conic Curves (Supp. 3.6) • Parabola: Curve created when a plane intersects a right circular cone parallel to the side (elements) of the cone

  17. Conic Curves (con’t) Parallelogram Method of Drawing Parabolas Engineering Applications of Parabolas

  18. Conic Curves (con’t) • Hyperbola: Curve of the intersection created when a plane intersects a right circular cone and makes a smaller angle with the axis than do the elements

  19. Ellipse: Single-curved-surface primitive – created when a plan passes through a right circular cone at an angle to the axis that is greater than the angle between the axis and the sides (a circle when viewed at an angle appears as an ellipse) Conic Curves (con’t)

  20. Conic Curves (con’t) Constructing a Foci Ellipse

  21. Next Class • Pictoral drawings • Next Week, Midterm 1 at the Testing Center (25 AutoCAD questions, to be answered on the bubble sheet, and manual drafting related questions – up to dimensioning). Bring your drafting tools. • Midterm 1 is a timed exam. 120 min. But anticipating a few minutes differences between your watch and Testing Center’s clock, actual max time allowed is 125 minutes.

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