Question 4 of 5: Section view of a stepped plate with a counterbored boss
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
National Exams, 04-BS-15 Engineering Graphics & Design Process, 2017-Dec. Closed-book, no calculator; five questions constitute a complete exam paper, and all sketches must be freehand (no straightedge).
[Figure not reproduced: Exam figure, page 5: TOP and ISOMETRIC (upper), FRONT and RIGHT-SIDE (lower) views. See the official exam paper or the cited reference text.]
Exam figure, page 5: TOP and ISOMETRIC (upper), FRONT and RIGHT-SIDE (lower) views.
Reading the part. Proportions from the views, overall 100 long × 50 deep:
Stepped plate. The left half is full thickness (≈24). The right half is a thinner flange (≈12), flush with the top, so there is an open step underneath. It shows in the front view and as the notch in the isometric; the dashed line in the top view is the step, hidden below.
Boss. A cylindrical boss (⌀≈25, ≈24 high) on the left half, centred in the depth.
Counterbored hole through the boss. The three concentric circles in the top view are the boss outline, a shallow counterbore (⌀≈20, ≈5 deep) and a through-hole (⌀≈10) down to the bottom face. The hidden lines in the front and side views show the step between them.
Two mounting holes (⌀≈12.5) through the thin flange, placed symmetrically about the centre line.
The hidden-line clutter is inside the boss, so the section must pass through the boss axis.
Choice of section: offset section A–A, in the front-view position.
The cutting plane runs along the boss centre line, cuts the counterbore and through-hole, then jogs within the thin flange to pass through the rear mounting hole.
One view then shows the counterbore diameter and depth, the through-hole, the full-thickness and thin portions, the step, and a mounting hole, with no hidden lines.
A full section on the centre plane is also acceptable. It shows the boss detail but misses the mounting holes, which are simple through-holes already clear from the top view.
Conventions applied:
The cutting-plane line is a thick chain line in the top view, with arrows showing the line of sight (toward the back for a section placed as the front view) and labelled A–A.
Solid material cut by the plane gets thin 45° hatching, uniform for the one part. The holes are left unhatched.
The jog is not drawn in the section; an offset section is drawn as if on a single plane.
Visible edges beyond the plane are drawn, for example the counterbore step line across the bore. Hidden lines are omitted.
Centre lines are drawn on the hole axes.
Fig. Q4 — top view with offset cutting plane A–A (arrows = line of sight) and SECTION A–A: counterbore, through-hole, step and mounting hole shown without hidden lines.
