Question 9 of 10: Two Section Types — Full, Half, Offset (any two of three)

Question 9: Two Section Types — Full, Half, Offset (any two of three) (9 marks)

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.

Given. No part is supplied. A simple symmetric stepped cylindrical part (a shaft collar with a central bore) is used to illustrate full and half sections, since a half section specifically requires an object that is symmetric about its centreline — an offset or asymmetric part cannot be half-sectioned meaningfully.

Find. Two of the three listed section-view types, correctly labelled and hatched, on the same or comparable part so the difference between them is visible.

Approach. Full section: the cutting plane runs completely across the part on one straight line, and the ENTIRE resulting view is drawn as if that half of the material were removed — every interior feature the plane crosses is exposed and hatched. Half section: used only on a symmetric part, the cutting plane removes just one quarter of the material (imagine cutting in on one radius and out on the perpendicular radius); the resulting single view shows one half as a normal EXTERIOR view and the other half as a full interior section, split by a single centreline (not a solid line) down the middle — giving both the outside appearance and the inside detail in one view.

1. Full section — cutting plane. Mark a single straight cutting-plane line through the shaft collar's centreline, arrows showing the direction of sight.
2. Full section — view. Draw the entire cross-section as if the front half of the part were sliced away: the outer profile, the central bore (unhatched, open) and the solid collar material (45° hatched) both appear across the full width of the view.
3. Half section — geometry. Because the collar is symmetric about its vertical centreline, remove only the front-upper quadrant of material (a quarter, not a half, of the physical part) conceptually.
4. Half section — view. The resulting single view shows the LEFT half exactly as it would look unsectioned (ordinary solid outline, no hatching — the untouched exterior) and the RIGHT half as a full interior section (bore open, collar material hatched); the two halves meet on a CENTRELINE, never a solid boundary line, since there is no physical edge there.
5. Compare and label. Both views keep the same centreline through the bore; each is labelled with its section type directly beneath.