Get Smart With Fusion 360 Part 4: What’s the Difference Between Loft vs. Patch?

In Part 3 of this series, we learned the difference between Loft with Guide Rails and Loft with Centreline. In Part 4, we’ll learn the difference between Loft vs. Patch, and how we can apply that knowledge.

What is a Loft?

When we ask Fusion 360 to ask Autodesk Shape Manager (ASM) to generate a surface using the Loft command, ASM will create a four-sided surface. It will then ‘fit’ the surface to the geometry we have provided.

For this reason, Loft works well when creating four-sided surfaces. Loft also works pretty well when creating surfaces that have more than four edges. In this case, however, Loft will just divide the shape up into four-sided surfaces for us. This is why your Lofted surfaces will always have at least one visible edge.


What is a Patch?

The Patch tool also allows us to create surfaces from multiple profiles. The Patch tool can also  ‘Warp’ surfaces, allowing us to set curvature continuity on its boundaries (Read Part 1 of this series for a definition of Curvature continuity).

A Patch is also a four-sided shape, but instead of fitting the patch to its inputs, ASM will trim the patch surface to the inputs.


When should I use Loft instead of Patch?

Loft is great for covering large areas. Loft creates a ‘ruled surface’, meaning the shape goes directly from one profile to another without dips.

When should I use Patch instead of Loft?

Patch is best used for surfacing a non-four-sided edge chain. Patch is the only tool that will fill a single entity shape (a circle!). It also has an excellent ‘Tolerance’ feature, meaning that the edge chains don’t have to join perfectly at the corners for the Patch tool to return a result.


Get Smart With Fusion 360 Part 5: Filleting Best Practices

Stay tuned for ‘Get Smart with Fusion 350. We’ll take a closer look at how the 3D modeling tools in Fusion 360 work under the hood. You’ll also learn what to do when your fillet operations fail.

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credit-Paul Munford via Autodesk

Get Smart With Fusion 360 Part 2: What is a Sweep in Fusion 360?

When is a feature a sweep?

What do the following Fusion 360 3D modeling commands have in common?

  • Extrude
  • Revolve
  • Coil
  • Pipe
  • Rib
  • Web
  • Hole
  • Primitives (Box, Cylinder, Sphere, Torus)
  • Ruled surface
  • Sweep

The answer is that they all create features with a consistent cross-section. This is known as ‘translation.’ The cross-section is translated along a path. In Fusion 360, this cross-section is called a ‘profile.’

Under the hood, ASM (the Autodesk Shape Manager) uses the same algorithm to create all these features.

The difference between a swept form created with the Sweep command and a swept shape created with commands such as Extrude or Revolve is that a Sweep path is explicit. We create it ourselves. The other commands translate a cross-section along an implied path. For example, an extrude path is implied as perpendicular to the sketch plane, whereas a revolve path is implied as an arc around the axis.

The path is implied by Fusion 360. Fusion 360 passes the Profile (cross-section) and the path to ASM, which generates a 3D shape. It then passes it back to Fusion 360 to display on the screen.

Therefore, I know you created a sweep today – even if you didn’t use the Sweep tool to create it!

What can I do with a sweep?

The one rule of sweeps is that they must have a consistent cross-section. However, we do have some additional controls for sweeps.

You can scale the cross-section (think ‘Taper’ in the Extrude or Sweep command), and you can rotate the cross-section (think ‘Twist’ in the Sweep command).


What can’t I do with a sweep?

The sweep algorithm accurately maintains a cross-section along a path, so swept forms can only have one profile.

How can I sweep between multiple profiles?

Well, you can’t. At least, not with the sweep command! If you need to create a shape using multiple profiles, you’ll need to use the Loft command.

Loft with centerline

The ‘Loft with Centerline’ command uses a hybrid algorithm that can sweep multiple profiles along a path and ‘warp’ the shapes between the profiles simultaneously.


How does a guide rail control the shape of a sweep?

You can use guide rails and surfaces to control the rotation (twist) of a profile along a path. When sweeping a guide rail, imagine lines drawn between your path and your guide rail. As these imaginary lines rotate around the path, the profile will rotate with them.


How does a guide surface control the shape of a sweep?

A guide surface is similar, but this time the twist is in relation to the surface normal. ‘Normal’ can be thought of as perpendicular to a surface.


When should I use a sweep?

Since a sweep must maintain a consistent profile, we can’t create sweeps that are curvature continuous to other geometry. For this reason, it’s usually a good idea to start with swept features (for example, extrude or revolve) as your base features. Then, use Loft or patch to create features that are curvature continuous with the base features.

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credit- Paul Munford via Autodesk

Get Smart with Fusion 360 Part 1: 3D Modeling Terminology

Part 1 of this series will cover the Autodesk Shape Manager and some key 3D modeling terminology to have in your vocabulary.

In this series, ‘Get Smart with Fusion 360 Modeling’, we will find out how Fusion 360 generates shapes for us. As a result, we’ll gain a better understanding of how we can achieve the geometry we want. For example, Did you create a sweep with Autodesk Fusion 360 today? That’s a trick question! I know you did, but you may not have used the sweep command to do it. Stay tuned to find out what I mean.

In the meantime, Part 1 will cover the Autodesk Shape Manager and some key 3D modeling terminology to have in your vocabulary.

Introducing the Autodesk Shape Manager (ASM)

To generate 3D shapes, Fusion 360 calls on the Autodesk Shape Manager (A.S.M). ASM is a modeling ‘Kernel’ – a software component that calculates 3D shapes. Fun Fact: ASM is also used by AutoCAD and Autodesk Inventor (among others).

ASM uses the Boundary Representation (Brep) method of calculating shapes. Breps are shapes based on Vertices. Two vertices can define an edge. A loop of edges can define a face. A collection of edges defines a volume (a 3D shape).

When we create 3D forms In Fusion 360 from commands such as Extrude, Sweep, or Loft – we are using the Fusion 360 user interface to pass coordinates to ASM, which calculates the Brep and passes it back to Fusion 360 to be shown on your screen.

Important terminology

Let’s make sure that we are all using the same language when we talk about shapes inside Fusion 360.

Geometry & Topology

Geometry can be thought of as the shape we want to create. Topology is how we get there.

The same geometry can be created using different topology. The same topology can be used to create very different geometry.

  • Geometry – the mathematics that describes the shape.
  • Topology – The vertices, edges and faces that form the shape.


‘Perpendicular to an edge or surface.’ For a solid model, the normal must always point ‘outwards’ from the solid volume. In Fusion 360, the back of a surface is indicated by a ‘Golden’ color.

Curvature Continuity

When we would like to create a smooth transition between two surfaces, we can describe the condition as ‘Curvature Continuous’.

Curvature continuity is the process of matching properties across two surfaces. We describe these properties using the letter ‘G’.

The properties are accumulative – G3 continuity includes G2, G1 & G0.

  • G0 Continuous: The edges meet (also known as ‘Touching’ or ‘Position’).
  • G1 Tangent: The surface normals match along the meeting edges (A fillet).
  • G2 Curvature: The amount of curvature matches along the meeting Edges.
  • G3 Acceleration: The rate that the curvature changes is equal, leading into the meeting edges.

Note: Mathematically, you could describe additional levels of ‘G’ (G+), but they won’t help us create awesome models.

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credit- Paul Munford via Autodesk



North West manufacturers are starting to integrate Fusion 360

According to a recent article on “Manufacturers in the North West are being urged to accelerate technology adoption to adjust to the economic challenges.

Made Smarter, the movement connecting UK manufacturing industries to digital tools, conducted a survey of 200 SME manufacturers in the North West and the results highlighted that achieving growth by improving productivity and adopting digital technologies are key drivers for SMEs.

Manufacturers revealed they had plans to adopt new technology in the next two or three years including integrated digital technology.”

One such form of integrated digital technology currently being embraced by many SMEs is Autodesk’s Fusion 360, a cloud-based 3D modelling, CAD, CAM, CAE and PCB software platform for professional product design and manufacturing.

In this blog we’re going to focus on the 3D CAD/CAM aspect of Fusion 360 and it’s benefits.

Fusion 360 enables the user to quickly create or import designs from other platforms and then either create new features or edit existing ones. Workholding devices can be designed or inserted into the workspace within the integrated CAD/CAM platform.

Once the model and workholding has been defined, Fusion 360 makes it easy to translate the part to a CNC program ready for manufacture by changing the work environment, thus doing away with the need for exporting the file to a third-party CAM package. In doing so, the time to market the product can be reduced by considerably, all within one CAD/CAM solution. By using Fusion 360’s CAM environment, programming, cycle and inspection times are all reduced.

Fusion 360 has a vast array of manufacturing features which can speed up the manufacturing process considerably, such as:

2D and 2.5D machining: Set up jobs and create 2D and 2.5D toolpaths. Integrated CAD simplifies design revisions, reduces programming times, and helps avoid mistakes.

3-axis machining: Create high-quality NC code using powerful 3-axis machining strategies. Rough and finish 3D parts with intuitive workflows.

Multi-axis positional machining: 3+1 and 3+2 (positional) machining creates parts with fewer setups, using shorter, more rigid cutting tools to improve part accuracy and faster cycle times.

4 and 5-axis simultaneous milling: Uses specialised 4 and 5-axis toolpaths to achieve superior surface finish.

Turning: 2D turned parts can be programmed using a suite of dedicated turning strategies. Verify turning toolpaths with stock simulation and identify errors or collisions with the model, stock, tools, and workholding device.

Turn-Mill: Produce more complex parts by combining milling and turning operations. Generate NC code for multi-tasking hardware, capable of supporting both styles of machining.



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