Question 5 of 9: Dimension an orthographic projection

Question 5: Dimension an orthographic projection

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.

The part is a stadium-ended plate with a rectangular notch cut from one end and two round holes on its centreline, shown in top view, plus a ramped side profile. Full CSA/ANSI dimensioning requires: overall size dimensions (never duplicated across views), a size dimension for each distinct feature (holes, notch), location dimensions referenced from a consistent datum/centreline, and no redundant or missing dimensions.

Approach. Dimension each feature once, at the view where it shows in true shape/size: the stadium length and width, the notch width/depth, the two holes by diameter symbol and their centre-to-centre spacing (located from the same datum edge), and the ramp length/heights on the side view. Centrelines mark the hole axes; extension and dimension lines follow standard offset/gap conventions (no dimension line crosses an object line).

1. Overall size. Length and width are given once, off the plate outline, not repeated on both views.
2. Feature sizes. Each hole is called out once with the diameter symbol ø and a "2×" note since both holes share the same size; the notch gets its own width and depth.
3. Locations. Hole spacing is referenced from the first hole’s centreline to the second’s, avoiding a chain of small dimensions that could accumulate tolerance error.
4. Ramp profile. The side view is dimensioned by its overall length; the ramp start location is implied by the hidden line already shown, so it needs no extra dimension.