Using Construction Planes in Fusion 360 - Bringing your sketches to new heights Using Construction Planes in Fusion 360 - Bringing your sketches to new heights
Autodesk Fusion 360 is a powerful sketch-based CAD/CAM design tool that is FREE for hobbyist makers. The tool allows one to make two-dimensional CAD drawings and extend them into the third dimension by adding what Autodesk calls "features" to your drawings. In this blog post, we'll dive into what that process looks like in a step by step guide.

There is an upcoming Fusion 360 online class covering these and similar concepts, sign up today!

First, Fusion 360 allows one to "extrude" a 2D square into the third dimension to create a 3D cube. The extrusion extends outward at right angles to the length and width dimensions thus extending the 2D CAD drawing into the third dimension which in turn allows it to then be 3D printed or milled by a CNC machine.

Fusion 360 features like "extrude" and "revolve" applied to 2D shapes are extremely useful but they perform a very specific function and can be somewhat constrained in how they add the third dimension to your digital design. For example, the extrude feature can only extend the height of a singular outline, the outline does not and cannot change throughout the change of height so even though that feature is extremely powerful, it is limited in that particular way.

If you are looking to expand your creativity and want to connect two (or more) totally different outlines and create a smooth surface between them, you'll need to use the "loft" feature. The loft feature allows you to transition from one outline to a totally different outline and Fusion 360 extrapolates the resulting surface to connect the two. You can access the loft feature by clicking the "S" key to pull up the search box then type in loft  and clicking or by clicking create in the top menu bar then selecting loft.

The challenge becomes, how do I tell fusion what sketch to start from and which to end at? Furthermore, how do I draw sketches at different heights, this is where the Construction offset planes come in to play. Offset planes are a sub element of Construction objects and although they appear on screen, they do not show up as active objects in the design. They are simply there as guides to help you place other objects in space and are passive in nature.

For Construction Planes, you can designate a new plane in the workspace that is offset from another plane by a certain distance, in our case height. So If I have a sketch of a circle and I wanted to extend a loft to a sketch of a triangle 30 mm above it, I could create a construction plane, solely for the use of creating and placing the new sketch of the target shape.

The workflow looks like the following:
  • Create you first sketch
  • Choose any plane to sketch upon
  • Place a circle on the sketch
  • Click finish sketch
  • click "Construct" then "Offset plane" in the top toolbar
  • type S to pull up search window, type in "offset", select offset plane

  • click on the original sketch plane with the circle on it or the circle itself, you should see it highlight
  • Pull to the arrow to set the desired height OR enter the height numerically, 30mm for this example, click enter to confirm

  • click create sketch
  • click on the newly created offset construction plane as the sketch surface

  • draw a triangle
  • click finish sketch

At this point you should have two shapes on the screen, the lower circle and the upper triangle. Assuming you have clicked the finish sketch button, type "s" for the search window and enter loft in the search field. Click the loft command OR alternatively you can click on the create menu item from the top tool bar and choose loft. It will then prompt you to select the sketches to extend the loft between..

To see the final loft,
  • click the circle to select as the sketch as origin
  • click the triangle to select sketch as destination
  • you should see a preview of the new body that is created
  • make tweaks as needed, click OK to accept the new body 

The result should be a new body that smoothly transitions from one shape to the other. Experiment to see how changes to the sketches and loft attributes change the body.

Jump on the Hackerlab Discord and let us know if this worked for you. Did you successfully use the feature; show us your work and tell us about anything else you've learned.

Happy Hacking!

P.S. There is an upcoming Fusion 360 online class covering these and similar concepts, sign up today.

About Curtis Soldano: 
Curtis Soldano is a long time technologist, tinkerer and maker who wants to share his excitement for using cool tech to make cool stuff. He has been with Hacker Lab since before the establishment of the mid-town location and has volunteered his time on many occasions to help grow Hacker Lab by providing elbow grease and skilled electrical maintenance and installations. Curtis’ educational foundation is in Digital Electronics and separately he attained his California State Electrical Contractor license in 2004 after apprenticing for his father in the family business for many years. Curtis’ also worked for over 20 years as producer for top tier tech and entertainment companies like EA, Disney, Atari, Playdom, E*TRADE, GSN and Sega.

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