04-BS-15 · December 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Basic Studies / 04-BS-15 — Engineering Graphics & Design Process, December 2018. Closed-book, no calculator, 3 hours, 100 marks; five questions constitute a complete exam paper (answer ALL five). All sketches are freehand technical drawings following third-angle projection (CSA B78.1 / ASME Y14.5) unless the question calls for isometric pictorial or sectioning conventions.
Reference texts: Bertoline & Wiebe, Technical Graphics Communication (4th ed.) — orthographic projection, isometric pictorials, auxiliary/section views, third-angle projection; Giesecke, Technical Drawing / Engineering Graphics (15th ed.) — ASME Y14.5 dimensioning, CSA B78.1 drafting practice, sectioning conventions, glass-box projection theory.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
[Figure not reproduced: Given top, front and right-side views. See the official exam paper or the cited reference text.]
Given. Read the three views together. In third-angle projection TOP sits above FRONT and RIGHT SIDE to the right of FRONT. TOP and FRONT share widths, FRONT and RIGHT SIDE share heights, and the depth in TOP (measured up from its front edge) equals the depth in RIGHT SIDE (measured right from its front edge). The part is a rectangular block, about 60 wide × 42 deep × 40 high in proportion, with four features. (1) A 45° chamfer along the whole top-left edge: the sloped line at the top-left of FRONT and the vertical line near the left of TOP. (2) A 45° chamfer along the top-front edge of the left portion: the sloped line at the top-left of RIGHT SIDE and the horizontal line across the left part of FRONT. These two chamfers meet in a mitre, which is the short diagonal at the front-left corner of TOP. (3) A rectangular notch in the front-right, open to the front, top and right faces. It runs back about 60% of the depth and has its floor at half height; the front edge of the floor is bevelled 45° down to the front face. This gives the two horizontal lines in the right part of FRONT, the rectangle at the lower right of TOP, and the step and sloped line at the lower left of RIGHT SIDE. (4) A 45° chamfer along the top-right edge behind the notch: the sloped line at the top-right of FRONT, the short vertical line at the top-right of TOP, and the horizontal line at the upper right of RIGHT SIDE. When this solid is projected it reproduces every printed line. The printed RIGHT SIDE view leaves out one hidden line, the foot of the top-left chamfer, which the notch’s left wall hides. That omission does not change the solid.
Start from the enclosing box: lay off the overall width, depth and height along the three isometric axes, with the receding axes at 30° to the horizontal. View from the front-right-top so that the notch, its bevelled floor, the front chamfer and the rear-right chamfer all face the viewer. Then remove the features one at a time. Every point is located by measuring along isometric lines only. Each sloped (non-isometric) edge, such as the chamfers, the bevel and the mitre, is drawn by plotting its two end points and joining them, never by measuring along it. From this viewpoint the top-left chamfer’s normal is perpendicular to the line of sight, so that face is seen edge-on and appears as a single line. Its edges still bound the top face and the left face.
No hidden lines are drawn in an isometric pictorial sketch; only visible outlines and visible internal edges (the chamfer, bevel and notch edges) are shown, which is standard freehand isometric-sketching practice.
