Breaking Edges in Google SketchUp 7

Bonnie Roskes
Independent Writer and Consultant

One of the new features in SketchUp 7 is its ability to break edges in 2D. This may seem like a minor improvement, but for those used to the “old” way, this new feature will cause us to do things a little differently.

Consider this example: a house that needs a roof. The yellow face is a cross-section for the roof, and this face needs to be driven along the top edges of the walls.

Let us first look at how you would complete the roof in SketchUp 6.

The yellow face is needed on both sides of the house, so make a copy of it and the top edge of the front wall (this edge is needed for reference when moving the copied face back into place). Use the Scale tool to turn the copy inside-out (using a scale value of -1).

To create the roof on one side of the house, first select the two edges shown below.
 

Activate the Follow Me tool, and click the roof face.

For the roof on the other side, start by moving the copied roof face and edge into place. The face remains whole—you can select the whole thing with one click.

Use Follow Me to create the second half of the roof.

Use Intersect with Model to create intersection edges, then erase edges and clean up as necessary to get the final roof.

Let’s now look at how to create the same model in SketchUp 7.

Start with the same roof faces, and use Follow Me to create half of the roof.

Move the copied face into place, and here’s what happens—the original roof face breaks the new one into three separate faces.

If you use Follow Me on this new roof face, only part of it is driven along the house.

In Version 7, if you want to prevent a face from being broken by other faces or edges, you need to protect that face within a group or component. Going back to this step, make the copied face and edge into a group.

Move the group into place. Here’s how to use Follow Me on a face inside a group—first select the edges to use as the path.

Activate Follow Me, then right-click on the group and choose Edit Group.

Click the roof face, which is driven along the path, still within the group.

After you close the group, you need to explode it before it can be intersected and trimmed.

Intersect and trim to get the result shown below.

This roof example showed a case in which the new “Break Edges” feature requires you to add a few extra steps, but in other cases, this feature will save you from extra work. Consider a window, on which you add a vertical and horizontal edge between midpoints.

In SketchUp 6, you would have to trace half of one of these lines to divide it in half. In SketchUp 7, the edges divide each other, and the window is divided into four faces, with no tracing needed.

About the Author

Bonnie Roskes is the author of Google SketchUp 7 Hands-On: Basic and Advanced Exercises, which is her sixth release on SketchUp. She has also authored the Google SketchUp Cookbook, published by O’Reilly media. In addition to pro-level books, Bonnie also has a Student Coursebook on SketchUp, as well as design project books and geometry project books for kids in K-12. For info on all of Bonnie’s books, as well as free resources for teachers and parents, go to www.3dvinci.net.

Bonnie has also authored books on Piranesi and OneCNC, as well as reference manuals, user guides, and tutorials for other CAD applications. She has a BS and MS in structural engineering, and worked for several years in bridge design and analysis before moving to tech writing.

Contact bonnie@3dvinci.net for info on any of her materials.

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