04-BS-15 · December 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Reference texts: Bertoline & Wiebe, Technical Graphics Communication; Giesecke, Mitchell, Spencer et al., Technical Drawing / Engineering Graphics (ASME Y14.5 dimensioning practice, CSA B78.1 Canadian drafting conventions).
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 view: C-slot bracket with rounded end and two holes. See the official exam paper or the cited reference text.]
[Figure not reproduced: Given front view: stepped/wedge profile with hidden lines. See the official exam paper or the cited reference text.]
CSA/ANSI dimensioning practice places size dimensions on the feature that shows it true-shape (diameters on the circular/side view, the slot width on the view where it reads as a true rectangle) and location dimensions from a consistent datum edge, avoids duplicate/chain dimensions, and keeps dimension lines outside the object outline wherever possible.
Approach. Establish the left edge of the C-slot as the horizontal datum and the centreline through the two holes as the vertical datum; dimension the overall length and width once each, the C-slot as a location + two size dimensions, the two holes by a centre-to-centre spacing plus one hole-to-datum location, and the rounded end with an “R” radius callout equal to half the part width (tangent, so no linear dimension is needed for it) — a set that covers every feature without a single redundant (over-defining) dimension.
| Dimension | Value (mm) | Type |
|---|---|---|
| Overall length | 120 | size |
| Overall width | 50 | size |
| C-slot depth (from left edge) | 28 | size |
| C-slot opening width | 18 | size |
| C-slot vertical location (from bottom edge) | 16 | location |
| Hole diameter (2 places) | ⌀12 | size |
| Hole spacing (centre-to-centre) | 30 | location |
| First hole from datum edge | 75 | location |
| Rounded end radius | R25 (= half width, tangent) | size |
