Line Types and What Each One Claims
≈ 38 minLine Types and What Each One Claims
In EGD the kind of line carries meaning, not just its position. Four types do most of the work:
- Continuous thick — a visible edge. You could touch it.
- Short dashes — a hidden edge. It exists, but material is in front of it.
- Long-short-long chain — a centre line. It marks an axis or symmetry; it is not an edge at all.
- Continuous thin — construction, projection and dimension lines: the working that got you there.
Worked example. A block with a drilled hole through it: in the front view you see the hole's opening as a continuous thick circle. In the top view, where the hole runs into the material, the same hole appears as two short-dashed lines, with a chain line marking its axis. Three different line types describe one hole, and each says something different about it.
Core checkpoint: Before drawing any line, decide what you are claiming — visible, hidden, or axis — and use the line type that makes that claim.
A line drawn as short evenly-spaced dashes on a working drawing means:
What is the name of the long-short-long chain line used to mark the axis of a hole or the symmetry of a part?
A learner draws the axis of a drilled hole as a continuous thick line. What has this drawing now claimed about the object?
In the top view of a block with a hole drilled through it, why do the sides of the hole appear as dashed lines rather than continuous ones?