Simulic
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Sectional views – movable cutting plane, full, half and local sections

Design & TechnologyEngineering Drawing & DesignAges 15–16

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A 3D machine part (flanged bushing, flange with bolt holes, bracket with counterbored holes) is cut by a movable cutting plane; the front part slides away to reveal the cut surface hatched at 45°. Next to it, a first-angle drawing builds the full, half or local section automatically from the 3D part, with the cutting-plane line (chain line, thick at the ends, arrows and letters A) in the top view, the section labelled A–A and the hatched area updated as the plane moves.

Lesson: Sectional views: full section, half section and local (broken-out) section; cutting plane, cutting-plane line and hatching

What it shows

A sectional view shows the inside of a part as if it had been cut by a plane and the part nearer the viewer removed. Only the material lying in the cutting plane is hatched, with thin lines at 45°; edges behind the plane are drawn as visible outlines and hidden lines are usually left out. Here the section, the edges behind it and the top view are all computed from the same 3D model, so the drawing always matches the part. A full section cuts the whole part, a half section suits symmetrical parts, and a local section opens just one feature.

How to use

Choose a part and a section type, then drag the c slider or drag the A–A line in the top view to move the cutting plane. Watch holes appear, narrow and vanish in the section. Tick Show removed part to see the imagined cut-away piece, press Cut again to replay it, and rotate the 3D view to compare the cut surface with the drawing. In Local section, drag the break-out area across the section.

Parameters you can change

  • Part Flanged bushing, Flange with bolt holes, Bracket with counterbored holes
  • Type of section No section (view with hidden lines), Full section, Half section, Local section
  • Position of the cutting plane c (from the plane of symmetry) -40–40 mm
  • Show removed part (faint)

Questions to explore

  1. Why is the cutting plane of the flanged bushing usually placed through its axis of symmetry?
  2. Where must the cutting plane be placed so that the section of the flange shows the bolt holes?
  3. When is a half section better than a full section, and why does the bracket suit a local section?

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