Saturday, October 25, 2014

Designing a Project in 3D: Sketchup

Every project I've done so far started with a design. While some opt to use good ol' paper and a pencil to do their designs, I prefer to use Sketchup to do my designs. This fantastic (and free!) tool is one of the easiest applications I've found for 3D modeling of this caliber. I can easily create my surfaces, shapes, and even joinery and hardware choices to scale.

Early rendering of the chair. I added a model
of a person the same height as my wife for
For the rocking chair, there's lots of curvy parts — the back crest, the rockers, the seat, the arms. I could probably create these templates by hand, but I've already got the dimensions for them all set up and ready to go from the model.

Happily, Sketchup makes creating these templates fairly easy. The simplest of the templates was the rockers.  To make them, all I did was:

  1. Select one of the face surfaces. This forms the shape of the template.
  2. Copy and paste it to another part of the model space.
  3. Align the pasted face with one of the model axis (red, green, or blue).
  4. Switch the camera view into Parallel Projection.
  5. Highlight the face again, right click, and choose Zoom Extents. Next, repeat, clicking on Align View. This will align the camera to face your template straight-on.
  6. Resize your window and zoom / pan to center the template in the window with as little surrounding space as you can. This view is what will ultimately be printed.
  7. Print your template. Make sure that Fit to Page and Use Model Extents are both unchecked, and that Scale is set to 1 in both "in the printout" and "in sketchup", with the same units. To ensure the printout is accurate, click through both numbers there (the dimensions to the left won't be right until you do).
Printing a template for the back crest.
OK, so it's not all that easy, certainly not as easy as clicking a face and clicking "print." But once you get the hang of it, you can rattle off printouts of templates really quickly.

Another great feature is the X-Ray function. I used this frequently when figuring out how the (many!) spindles in the chair fit together, and how the dimensions should be. It's also easy to use this when creating the joinery, as you can see where each piece intersects and trace around them to create the joinery surfaces.

X-Ray view of the chair seat in Sketchup.
There's lots of plugins available for Sketchup as well. One I use quite frequently is Cut List, which will take your model and generate a diagram and list of wood to buy to complete the project. It even takes into account plywood boards and saw kerf size when making its calculations, and will split apart large pieces into smaller ones for glue-ups.

Beyond all of this, I take my measurements straight off the model as I'm cutting. Need to know how big a spindle should be? Just use the measurement tool! Need to figure out an angle? Measure that too with the protractor tool!

This certainly makes designing my projects a lot easier, and gives me more confidence that the project will come out successfully in the end. ■

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