AutoCAD 3D exercise: a pulley

Model this pulley by revolving its half section round its axis, in millimetres: a bore of 20, a hub 30 long and 40 across, a web 10 thick and a rim 24 wide from 90 to 110 across, centred on the hub. The section is drawn as distances from the axis, which runs up the Y axis, so each diameter is drawn as its half.

• Exercise: Intermediate · Mechanical · 3D solid
• Commands: PLINE, -VIEW, VSCURRENT, REVOLVE, ZOOM
• In the editor: Open it with its drawing, dimensioned beside where you draw yours

The drawing

Step by step

The engine draws each step and writes its history as you would type it: the prompts in AutoCAD 2027's order, with the same option letters. After a command's first point, a typed point is measured from the last one, as dynamic input measures it, and the history writes it with @; # measures from the origin.

1. Draw the half section

On the Outline layer, one closed PLINE from 10,0, each point after it a step from the last: 10,0, 0,10, 25,0, 0,-7, 10,0, 0,24, -10,0, 0,-7, -25,0, 0,10 and -10,0, then Close.

2. Turn the view

-VIEW and SEIso look at it from the south-east and above; VSCURRENT and Conceptual shade the faces, which shows a turned part best.

3. Revolve it

REVOLVE: pick the section and press Enter, then Y: the Y axis is the pulley's. Enter takes the default angle, a whole turn. ZOOM Extents frames it, and a scale of 0.8x leaves room round it.

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