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Lesson 3-05 – Sweep and Loft

🌪️ Lesson 3-5: Sweep and Loft

Create smooth, flowing, and custom 3D forms by sweeping profiles along paths and blending multiple cross-sections.

📚 What You’ll Learn

By the end of this lesson, you’ll be able to:

  • Use the SWEEP command to extrude shapes along paths
  • Use the LOFT command to create solids between multiple profiles
  • Understand when to use Sweep vs. Loft for organic or linear designs
  • Control twist, scale, and alignment during solid generation
  • Visualize and modify swept and lofted objects

🧰 Tools You’ll Use

Tool / CommandDescription
SWEEPProjects a profile along a path to create a 3D solid or surface
LOFTGenerates a 3D solid between two or more shapes
PATHGuiding line or curve used in Sweep
ALIGN / UCSEnsures profile orientation along path
3DORBIT / VIEWRotate and visualize created forms

❗ Why It Matters

SWEEP and LOFT allow for the creation of highly custom and complex 3D forms—such as handrails, pipes, handles, ducts, or organic contours—that can’t be built easily using basic extrusions or revolutions. These tools are essential for both mechanical parts and architectural modeling with smooth transitions and flowing geometry.

🌀 Sweep vs. Loft Comparison

FeatureSWEEPLOFT
Base ShapeSingle profileMultiple profiles
GuideRequires a path (line, arc, spline)No path required (optional guides)
OutputSolid or surfaceSolid or surface
Ideal ForPipes, rails, wiresShoes, sculptures, smooth transitional forms
ExtrasControl twist, scale along pathAdd guide curves for precision

🔧 Using the Commands

SWEEP Example

  1. Draw a 2D closed profile (e.g., circle or rectangle)
  2. Create a 2D or 3D path (line, polyline, arc, spline)
  3. Type SWEEP, select the profile, then the path
  4. Result: The profile is extruded along the path

💡 You can use 3D polylines, splines, or helixes for paths!

LOFT Example

  1. Draw at least two closed profiles (e.g., two different ellipses)
  2. Type LOFT, select profiles in order
  3. Optionally, add guide curves or path curves
  4. Press Enter – the lofted solid blends between profiles

💡 Loft is ideal when shapes vary from one end to another!

🛠️ Practice Activity

Objective: Model a decorative table leg using Loft and a pipe using Sweep.

Instructions:

Part 1: Lofted Table Leg

  1. Draw three concentric profiles (e.g., large circle, mid taper, small foot) on vertical planes
  2. Use LOFT to connect them smoothly
  3. Rotate model using 3DORBIT

Part 2: Swept Pipe

  1. Draw a circle (pipe cross-section)
  2. Draw a curving spline as a 3D path
  3. Use SWEEP to extrude the circle along the spline
  4. Change visual style to REALISTIC

🛠️ Best Practices

TipWhy It’s Useful
Keep profiles perpendicular to path (Sweep)Ensures smooth and correct orientation
Use consistent alignment (Loft)Prevents twisted or unexpected geometry
Use guide curves (Loft)Adds control for asymmetrical or irregular lofting
Clean geometryClose shapes and avoid duplicates to ensure clean modeling

🗺️ Visualizing and Editing

ToolUse
3DORBITRotate to check flow and alignment
SECTIONPLANEAnalyze cross-sections of the solid
SLICECut object for part inspection or visualization
PROPERTIESView and edit sweep twist angle or loft settings

📌 Quick Review

CommandDescription
SWEEPMoves a 2D profile along a path to create a 3D solid
LOFTBlends between multiple profiles to create complex forms
PATHRequired for SWEEP, optional for LOFT
GUIDESOptional for LOFT, to control shape transition
UCSAligns your view and drawing planes