Polytechnic · Fabrication Engineering Drawing · Interactive drawing lesson

Centre line

Chain thin, through every hole and axis. Learn centre line step by step in an interactive Polytechnic fabrication engineering drawing lesson.

What you will learn

This guided practical demonstrates the construction on a drawing board and explains the method in a clear sequence.

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More Fabrication Engineering Drawing lessons

• Full size (1:1) — The drawing and the job are the same.
• Reduction scale (1:2) — Half size, with true figures on it.
• Enlargement scale (2:1) — A small part drawn twice size.
• Dual scale — Metres and feet off one bar.
• Diagonal scale — Three orders of size from one scale.
• Plain scale — Whole units and tenths.
• Stepped block in third angle — Plan above, end view on the left.
• Stepped block in first angle — Plan below, end view on the right.
• Auxiliary views — True shape of a sloping face.
• Outline — Continuous thick — the visible edges.
• Centre line — Chain thin, through every hole and axis.
• Projection line — Carries a point between views.
• Construction line — The setting out you leave on.
• Dimension line — Arrowheads, spacing and the figure.
• Leader line — Takes a note to a feature.
• Limit line — Where a partial view stops.
• Phantom line — An alternate position, in chain double dash.
• Extension line — Brings a feature out to its size.
• Break line — A long bar drawn short.
• Cutting plane line — Where the job was cut open.
• Hidden detail line — An edge behind the metal.
• Open style lettering — Upright capitals at full width.
• Condensed style lettering — Narrowed to fit a tight box.
• Sloping style lettering — Capitals leaning 15°.
• Open style lower case — x-height, ascenders and descenders.
• Open style freehand — The same hand with no straight edge.
• Sloping style freehand — Leaning letters, freehand.
• Matchstick man and woman — A freehand proportion exercise.
• Isometric axis sketch — Three axes, 120° apart, freehand.
• Most representative views — Choosing the front view and top view.
• Isometric to first angle — Read a pictorial, draw three views.
• Cylinder cut by a plane — The first template: a mitred pipe.
• Junction of equal cylinders — A tee that meets in straight lines.
• Rake of a ship funnel — A cylinder cut by two sloping planes.
• Plates for a boiler dome — A dome saddled onto a curved shell.
• Boiler to superheater pipe — One pipe, saddled at both ends.
• Overhanging boiler front — A flanged blank and its bend allowance.
• Plates of an egg-ended boiler — Barrel strakes and end gores.
• Frustum not continued to a point — A taper whose apex is off the board.
• Rise and radius of a cone — Arcs bigger than your compass.