Extrude & Revolve - RoboCAD Academy

Interactive 3D Model: Solid Bracket - a part built entirely from simple 2D sketch extrusions.

From Sketch to Solid

Once a sketch is fully constrained (every line black), you pull it into the third dimension. The two most common ways to do that are Extrude and Revolve.

Extrude vs. Revolve

The two most common tools to create positive mass from a 2D sketch.

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Extrude

Pushes a flat profile straight along an axis to create boxy or prismatic parts - plates, blocks, brackets.

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Revolve

Spins a profile around an axis to make cylindrical, symmetrical parts - wheels, shafts, bottles.

Extrude Options

Distance, Direction, Operation

Distance: Exact length of the push, in mm or inches. Type the number, don't drag.
Direction: One side, symmetric (both sides), or two separate distances.
Taper Angle: Optional slope on the sides - useful for draft on molded parts.
To Face / All: Let the extrusion stop at an existing face or pierce all the way through.

Revolve Options

Profile + Axis = Solid of Revolution

A revolve needs two things: a closed profile on one side of an axis, and the axis itself (a line in the sketch or an existing edge).

Angle: Usually 360° for a full round shape, but you can do partial (180°) to make a half-shell.
Axis placement: The profile must not cross the axis - otherwise the solid would turn itself inside out.
Stepped shafts: Draw the stepped outline once, revolve 360°, and you get every diameter in one feature.

Tip: If your part is round in any direction - wheels, axles, bottles, gears - try revolve first. One revolve is usually cleaner than ten extrudes.

1 Experience

2 Reflect

3 Theorize

4 Apply

Pause and Reflect

If you wanted to design a round axle shaft with multiple diameter steps, would it be faster to use multiple Extrude operations or one Revolve operation? Why?

What happens if you set an Extrude's distance to "All" instead of typing exactly "10mm"? When is each option better?

✓ Your reflections are saved automatically

Apply What You Learned

Use your CAD software to build a custom spacer block and a round standoff.

Sketch a fully constrained square, centered on the origin
Extrude it 10mm to create a solid plate
Sketch the side profile of a stepped shaft (two diameters, two lengths)
Revolve 360° around the axis and confirm both diameters are correct

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