Concept reference for common 3D modeling objects used in functional part design.
Object Definition and Uses – Torus and Sweep
This reference defines what a Torus and a Sweep are , what they are typically used for , and how to decide
which one to use when modeling functional 3D‑printed parts.
A torus is a 3D shape created by revolving a circular profile around a perfectly circular path .
In practical terms:
A torus is a round tube bent into a perfect circle .
Path: Perfect circle
Cross‑section: Perfect circle
Cross‑section size: Constant everywhere
Common real‑world uses
O‑rings and round gaskets
Sealing rings
Rubber bumpers
Circular hoses or tubes
Rounded protective rings
Bearing race concepts
Why torus is preferred when possible
Simple geometry
Fewer constraints
Very stable models
Easy to edit later
Uniform compression for seals
When not to use a torus
Flat or rectangular gaskets
Non‑circular paths
Variable thickness parts
Organic or asymmetric shapes•
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A sweep is a modeling operation where a 2D profile is carried along a path to form a 3D object.
In simple terms:
A sweep means drag this shape along this path .
Required elements
Profile – the cross‑section (circle, square, custom)
Path – the route the profile follows (line, arc, spline, helix)
Common real‑world uses
Pipes and hoses with bends
Wiring and cable routing
Handrails
Weatherstripping
Non‑round gaskets
Any extrusion following a curved or irregular path
Strengths
Works with any path shape
Supports custom profiles
Can follow complex geometry
Tradeoffs
More complex to constrain
Easier to break
Harder to edit later
Relationship Between Torus and Sweep
A torus is a special case of a sweep : - Path = perfect circle - Profile = perfect circle - Cross‑section =
constant
Because of this, a torus should be used instead of a sweep whenever its constraints are met.1.
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Decision Tree – Torus vs Sweep vs Extrude
Step 1 – Is the path a perfect circle?
Yes → go to Step 2
No → Sweep
Step 2 – Is the cross‑section round and constant?
Yes → Torus
No → Sweep
Step 3 – Is the shape a flat ring or washer?
Yes → Extrude + Cut
No → continue
Step 4 – Does the cross‑section change along the path?
Yes → Sweep
No → Torus (if circular) or Sweep (if not)
Quick Cheat Sheet
Geometry Goal Best Tool
O‑ring / round gasket Torus
Rectangular gasket Extrude + Cut
Circular tube Torus
Bent tube or hose Sweep
Cable routing Sweep
Flat washer Extrude
Organic or variable profile Sweep
When to Use a Torus vs a Sweep
This section explains why and when designers switch between a torus and a sweep , and why this is
usually a design replacement , not a literal CAD conversion.•
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Sweep → Torus (Uncommon)
Replacing a sweep with a torus is uncommon and usually happens during cleanup or refactoring.
It occurs when the designer realizes that: - The path is a perfect circle - The cross-section is perfectly
round - The cross-section never changes
At that point, the sweep is doing extra work with no benefit. The correct move is to delete the sweep and
replace it with a torus .
Typical reason: the original model was over-complicated.
Torus → Sweep (Common and Intentional)
Replacing a torus with a sweep is much more common and usually intentional as the design matures.
This happens when any of the following become true: - The cross-section is no longer round (D-profile, bulb
seal, flat face) - The path is no longer a perfect circle (oval, offset, segmented) - Orientation matters (profile
must stay flat or rotate intentionally) - The design shifts from exploration to production-quality intent
A sweep allows the designer to express how and why the shape follows the path.
Mental Model
A torus is a shortcut — precise, simple, stable
A sweep is a statement of intent — flexible, expressive, controlled
Designers often: - Start with a torus to validate geometry - Move to a sweep only when requirements
demand it
Practical Rules of Thumb
If it’s round, constant thickness, and perfectly circular → Torus
If any of those conditions break → Sweep
Don’t "convert" — replace the feature with the correct one
Key Takeaway
Use a torus for pure geometry. Replace it with a sweep when the design becomes
engineered.•
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