What is a Sectional View? Definitions and Examples of Sectional Drawings for Students

Sectional drawings show what an object looks like as if it had been cut open or sliced through.

  • Show what an object looks like as if it has been sliced through
  • Should be ‘cut’ in a place that shows the most internal detail
  • A ‘section line’ is drawn to show where the item has been cut
  • Useful for showing how things are put together or assembled
  • Cut surfaces have diagonal ‘hatching‘ (angled parallel lines)
  • Pins, dowels, bolts, nuts etc are not sectioned (because the purpose of a sectional drawing is often to show where these items go)
  • The ‘cutting plane‘ shows where the object is cut (the arrows show the direction the section is viewed from)
  • Label both the section line and the section with the same letters, i.e. Section ‘A-A’
  • Show what would be seen if you look in the direction of the arrows
  • Do not show hidden detail
Section drawing lesson

Hatching guidelines for cut surfaces

  • Hatching lines should be parallel & evenly spaced
  • Lines can be on any angle (common to start with 45° lines) but must not be same angle as edge of object
  • Avoid having hatching that is parallel to one edge of the area
  • Hatch different areas on different directions
  • Hatching lines should be thin and approximately 2-4mm apart
  • Do not hatch any thin items like pins, dowels, bolts, nuts etc
  • When thin surfaces are cut through, they can be coloured black. This should only be for thicknesses less than 1mm
Section hatching rules
The left-hand example is incorrect because the hatching lines are on the same angle as one of the sides (this makes the drawing more confusing)
Section hatching rules
The left-hand example is incorrect because the hatching lines on the two separate components go in the same direction
  • If hatching really large areas, hatching can only be partially drawn, near the edges

Half Sections

  • Sections lines in which only half of the object is cut away
  • Usually used when the object is symmetrical
  • Allows both the external and internal view to be shown within one drawing

Part Sections

  • These are used when only small areas need to be cut away in order to show important details
  • The line where the part section ends is simply a thin wavy continuous line (as if part of the surface has been ‘torn’ away)

Revolved Sections

  • Shows a cross section rotated so that it can be seen
  • It is drawn in place on the normal view
Revolved section examples

Removed Sections

  • Removed section are revolved sections that have been moved away from the main view

Offset sections

  • The cutting plane can change directions and turn corners so that the most detail is shown (this is called an offset section)
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