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Spin Tool

BEGINNER
📖3 min read
Blender - Spin Tool

Introduction​

The Spin Tool is a powerful direct modeling feature in Blender that allows you to extrude selected geometry (vertices, edges, or faces) in a circular arc around a specific point. It is essentially a "rotational extrusion."

This tool is indispensable for creating curved structures such as:

  • Pipes and Cables: Creating smooth 90-degree bends.
  • Architectural Details: Arched windows, curved walls, or circular staircases.
  • Lathed Objects: Creating round objects like vases or columns from a profile (similar to the Screw modifier, but destructive/direct).

Key benefits:

  • Precision: Define exact angles (e.g., 90°, 180°) and the number of segments for smoothness.
  • Interactive: Use on-screen gizmos to adjust the spin axis and angle in real-time.
  • Continuous Topology: Automatically connects the spun geometry to the original mesh.

Documentation

Official Blender Manual: Spin Tool.

Workflow / Usage​

The Spin Tool works relative to the 3D Cursor by default. Placement of the cursor is critical for correct results.

Step 1: Set the Pivot Point​

The spin operation revolves around the 3D Cursor.

  1. Select the geometry you want to spin.
  2. Move the 3D Cursor to the center of rotation.
    • Tip: Select a vertex at the "hinge" point, press Shift + S, and choose Cursor to Selected.

Step 2: Activate the Tool​

  1. In Edit Mode, find the Spin tool in the left-hand Toolbar (icon looks like a pie chart).
  2. Alternatively, keep the Select tool active and use the Spin settings in the "Adjust Last Operation" panel (though using the active tool gizmo is often clearer).

Step 3: Configure Axis and Extrude​

  1. Ensure the correct Axis is selected in the top bar (X, Y, or Z). This depends on your viewing angle (e.g., if looking from Top View, use Z-axis).
  2. Click and drag the "+" gizmo that appears.
  3. Drag to define the angle.
  4. Open the Adjust Last Operation panel (bottom left) to fine-tune:
    • Steps: Number of segments (resolution).
    • Angle: Exact degree (e.g., 90, -180).
    • Auto Merge: Check this if you are spinning a full 360° to simple weld the first and last vertices.

Documentation for Methodology​

What to document when using the Spin Tool

In Your Method Section​

Describe that curved geometry was creating using the rotational extrusion method (Spin Tool) to ensure consistent segmentation. Mention the profile used.

In Your Decision Log​

Record the following when using this technique:

  • Segment Count: How many steps were used to approximate the curve (e.g., "16 segments for 90-degree bend").
  • Reference: If the curve was matched to reference footage or specific measurements.
  • Pivot Placement: How the center of rotation was determined.

Verification​

Check that the spun vertices align with reference imagery. Ensure no duplicate vertices exist if spinning 360 degrees (use "Merge by Distance").

Common Limitations​

The Spin Tool creates geometry destructively. If the curvature needs to change later, the geometry must be deleted and re-spun, or manually edited. For non-destructive workflows, consider using the Screw Modifier.

Example Methodology Statement​

"The 90-degree pipe bend was modeled by extruding the circular profile using Blender's Spin Tool. The operation was centered on the corner vertex with 12 segments to match the smoothness observed in the CCTV footage."

Summary​

Key Takeaways:

  • Always place the 3D Cursor first; it acts as the hinge.
  • Check your View Axis before spinning to ensure rotation happens in the correct plane.
  • Use the Steps parameter to control the poly-count of the curved section.