Conventional Representations: A Working Summary

Conventional Representations: A Working Summary

Three years of conventions, gathered into the set you must be able to apply without hesitation.

Line types. Continuous thick — visible edge. Short dashes — hidden edge. Long-short-long chain — centre line or axis. Continuous thin — construction, projection, dimension. Irregular thin — break line.

Not hatched in section when the plane runs along their axis: shafts, bolts, nuts, screws, washers, keys, pins, rivets, ribs and webs. All are solid, and hatching them merges them with the parts they join.

Threads. Crest continuous thick, root continuous thin. External and internal are mirror conventions of each other.

Repeated features. Draw one or two fully, mark the rest with centre lines, add a note stating quantity and spacing.

Springs and knurling. Springs: a few turns with a chain line through the omitted middle. Knurling: a small patch of cross-hatching, not the whole surface.

Assemblies. Adjacent components hatched at different angles or spacings so their boundary reads.

Core checkpoint: A convention is an agreement. Applied correctly the reader loses nothing; applied wrongly, the drawing states something false.