Tips and Tricks: Working with Motion Skeletons for Top Down Modeling

Recently, we posted some tips on top-down modeling and skeleton models. Today, we’ll take a closer look at motion skeletons. (Am I the first to notice that this would be a wicked cool name for a death metal band?)

Fortunately, you don’t have to glue cornflakes to your face to rock motion skeletons.

Motion skeletons are used as a design framework for mechanized assemblies. Parts are attached to body skeletons and assume their motion definition.

Image: This elliptical machine is a great example of a motion skeleton model. With PTC Creo Parametric, you canquickly bring an initial design skeleton to life by simulating the assembly’s motion.

Getting started

Motion skeleton models are subassemblies that contain design skeletons (standard skeletons or internal sketches) and body skeletons. You create standard skeletons using curves, surfaces, and datum features. They can also include solid geometry.

Before you create your motion skeleton, you need to create geometry for the skeleton. To do this, you create geometry references and design the mechanism and the body skeleton—simply sketching several connected curves can be enough.

Image: This model shows the mechanism and body skeleton (the thin blue lines/circle).

Creating the motion skeleton model

After you create your design skeleton’s geometry references, follow these steps to create a motion skeleton model:

  1. In an open assembly, click Model > Create. The Component Create dialog box opens.
  2. Accept the default name or enter a new one.
  3. Select Skeleton Model from the Type list and Body from the Sub-type list.
  4. Click OK. The Creation Options dialog box opens.
  5. Select a Creation Method:
  • Copy from existing—Copy the motion skeleton geometry from an existing skeleton model. Click Browse to select the model to copy.
  • Empty—Create a motion skeleton with no geometry. Geometry is added after the motion skeleton is created.
  • Create features—Create a motion skeleton with no geometry. The motion skeleton is active when you quit the dialog box.
  1. Click OK.

From there, you can add geometry and parts to your skeleton model.

To learn more about motion skeletons, register for free Learning Exchange credentials, and then log in and watch this video.

You can also check out the PTC Creo Help Center page About Motion Skeleton Models.

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