Dave Richards is an expert woodworker, contributing author to Fine Woodworking magazine, author of SketchUp Guide for Woodworkers – The Basics (DVD), and writer on the Design. Click. Build. blog. He has taught SketchUp to people all over the world, including sessions at SketchUp’s 3D Basecamp. The following is adapted from Chapter Three of his SketchUp Guide for Woodworkers – Advanced Techniques (eBook & DVD). If you've been hungry for a step-by-step SketchUp project to sink your teeth into, this is it!
SketchUp model of a Queen Anne-style table (rendered with Kerkythea).
The pad-foot leg is an interesting example of multi-axis turning. In the shop, you turn the foot and pommel with the blank held on its true centers; you offset the blank to a new set of centers to turn the tapered section. To draw the leg in SketchUp, you need to break it down in much the same way; draw the foot, the tapered section, and the pommel as three separate parts, which you then combine. And as in real life, the tapered section is aligned on an offset centerline.
Figure 1. The key dimensions for the pad-foot leg. The true centerline is shown in green; the offset centerline, in red.
Begin with a simple layout and make a component of each section as you draw it. To make it easier to see what you’re doing, use layers to control the visibility of the sections. I based the layout for this leg on Jon Siegel’s article, “Turn a Pad-Foot Leg,” in the January/February 2009 issue of Fine Woodworking. Constructing the model will be easier if you use these extensions:
Figure 1 shows the layout for the leg. The green line is the centerline of the blank, used to turn the foot and the transition at the base of the pommel. The red line is the centerline for the long, tapered portion of the leg. The two centerlines cross at the base of the pommel.
Make layers and a drawing surface
Begin by setting up four layers to control the visibility of the elements in the model space. You can see them in the Layers window on the right in Figure 2. I’ve named them Foot, Leg, Pommel, and Setup. Once you have finished the leg, you will delete layers and their contents. Remember, always keep Layer0 as the active layer, as shown by the radio button to the left of the layer name. This ensures that the edges and faces you create always remain on Layer0. Only the components will get assigned to other layers.
Ed. note: Read more about the importance of Layer0 here: SketchUp Layers: Part One – The Sacred Layer0
Figure 2. Set up layers for the parts of the leg, and create a face on the red-blue axes to serve as a drawing surface.
Create a drawing surface. This makes it easier to keep all the lines and curves for each section of the leg on plane. Use the Line or Rectangle Tool to draw a vertical face on the red-blue axes. Make the face the full height of the leg, or 24". The width isn’t important, but you’ll want to make it wider than the leg. This will give you a drawing surface.
Add layout lines. Place a horizontal line 6" down from the top. This marks the bottom of the pommel. Add a vertical line on the blue axis, as shown in Figure 2. Select all the geometry, make it a component, and assign it to the Setup layer. To do that, go to Window > Entity Info to open that dialog box; select the component and change the layer setting to Setup. Delete any guidelines you might have used to make the drawing surface.
Create the pommel
Begin drawing the leg with the pommel. There are two ways to make this component, depending on which version of SketchUp you have.
Figure 3. The newest version of SketchUp makes it easy to use the Polygon Tool to create the top face of the pommel and position it on the top edge of the drawing surface.
For SketchUp 2015 or newer. Use the Polygon Tool, which makes it easy to center the top of the pommel on the centerline of the drawing surface. Select the tool and set the number of sides to 4. Hover over the ground plane so the tool is oriented correctly (the cursor will turn blue) and hold the Shift key to lock that orientation. With SketchUp 2017, you can press the Up Arrow key to set the orientation properly. Click at the top of the drawing surface and on the centerline of the leg. Drag outward along the edge of the rectangle. Hit Control (Option on the Mac) to make the square circumscribed about a circle (see Figure 3). Type 7/8" and press Enter.
Use the Push/Pull Tool to make the pommel a little more than 6" long (you’ll want the extra length when you shape the transition from square to round). Delete the face at the bottom of the pommel. Make it a component and assign it to the Pommel layer.
Figure 4. To complete the drawing of the leg, rotate the drawing surface so it intersects the diagonal corners of the pommel. This ensures that the finished leg will be properly oriented.
Angle the drawing surface
For the rest of the leg, you’ll want to work across the diagonal of the blank. Rotate the drawing surface 45°, as shown in Figure 4. To keep from rotating the pommel component at the same time, select the drawing-surface component first and use the Rotate Tool. Rotate the drawing surface about the centerline and click the cursor on a corner of the pommel to stop the rotation. Turn off the Pommel layer by unchecking its Visibility box in the Layers window.
Lay out the foot profile
Draw the foot profile at the bottom of the drawing surface; align its right edge with the blue axis. Follow the dimensions shown in Figure 5. You’ll need a path for the Follow Me Tool, so draw a 48-sided circle, centered on the blue axis and below the layout, as shown. Select the profile face and the circle. Make a component of that geometry and assign it to the Foot layer. Turn this layer off.
Lay out the long tapered section
Begin this part of the model by drawing the offset centerline. To calculate the offset, subtract the radius of the ankle from the radius of the foot. In this case, the offset is 7⁄16".
Place a guide point. Choose the Tape Measure Tool and click at the origin. Drag the tool along the bottom edge of the drawing surface, type 7/16", and press Enter.
Figure 5. Lay out the profile of the foot and add a circle for a Follow Me path.
Figure 6. Place guide points and guidelines to locate the offset centerline on the drawing surface.
Locate the offset centerline. The offset centerline has to pass through the true centerline at the base of the pommel. Use the Tape Measure Tool to place a guideline between the crossed lines on the drawing surface and the guide point at the bottom. Use the Line Tool to trace over the offset guideline from the top edge of the drawing surface down and off the bottom edge a little way (see Figure 6). If you want to know the top offset for layout in the shop, measure it now with the Tape Measure Tool.
Mark the top of the tapered section. Set a guide point along the horizontal line that defines the bottom of the pommel. Place the guide point 3⁄4" from the centerline.
Figure 7. Place guidelines to mark the radius of the ankle and foot, then outline the tapered section of the leg.
Place guides for the ankle and foot. These guidelines, for the ankle and foot radius, are placed from the offset centerline, not the true center. Click the Tape Measure Tool on the offset centerline and drag the cursor across the bottom edge of the drawing surface. The ankle radius is 7⁄16"; the foot radius, 7⁄8". Place two more guidelines from the bottom of the drawing surface to mark the height of the ankle (3⁄4") and the height at the top of the foot (11⁄4"). Use the Line Tool to outline the tapered section of the leg, as shown in Figure 7.
Add a curve. Use the Classic Bezier Curve Tool from the Bezier Spline tool set to draw a curve for the transition from the tapered section to the tip of the toe; see Figure 8. (In this instance, the 2-Point Arc Tool won’t give you the desired curve.) When you draw this curve, make sure none of the control points cross the guidelines. If they do, the extruded shape will be undercut.
Finish the leg profile. Draw a vertical line part-way down from the end of the curve toward the bottom of the drawing surface (see Figure 8). Draw another line back to the offset centerline. Turn the Pommel layer on and place a guideline along the component’s left edge. Then turn off the Pommel layer. This guideline will help you draw the pommel transition. Use the 2-Point Arc Tool to draw a curve that begins where the edge of the leg intersects the line representing the bottom of the pommel and extends beyond the guideline you just placed. Changing the size of the arc and the position of the upper endpoint will affect the shape of the pommel transition. The shape of the curve isn’t critical, as long as it looks pleasing to your eye. However, the curve must extend beyond the guideline marking the corner of the pommel. Close the loop of lines and curves to create a face by drawing a line from the top of the arc over to the centerline.
Figure 8. Add lines to finish the bottom portion of the leg.
Add a path. Next, add a path for the Follow Me Tool; that’s the reason for the extra line at the bottom of the leg. The path circle needs to be perpendicular to the offset centerline. The easiest way to accomplish that is to use the Perpendicular Circle Tool from the Perpendicular Face Tools extension. Set the radius of the circle to 1" or so; the exact radius isn’t important. Click at the end of the offset line and presto! A circle perpendicular to the line will appear.
Smooth the circle. Explode the group containing the circle; open the Entity Info window and change the number of sides of the circle to 48. If you omit this step, the leg and foot may not intersect properly. Make a component of all of this geometry and associate it with the Leg layer.
Figure 9. Copy all the parts of the leg, move them away from the originals, and scale the copies to finish shaping them.
Begin assembling the parts
Turn off the visibility for the Setup layer and turn on the visibility for the Pommel and the Foot layers. You should have something that looks like the collection of components on the left in Figure 9. A few of the upcoming operations will result in some very short edges and tiny faces. Although these small edges and faces can exist, SketchUp won’t create them at that small size. If you run a routine such as Follow Me with the model at its normal size, you’ll find you’re left with holes that you don’t want. One way to work around that is to scale the model up, run Follow Me and whatever other operations you need, then scale back down afterward. I have developed a slightly different method.
Since you’ve been making components here, you can leverage the fact that editing one instance of a component in a model results in all other instances of the component being edited in the same way. So make a copy of the components, scale the copies up, run Follow Me and whatever else is needed. Then close the large copies to exit edit mode and delete them. Zoom Extents will return you to the original component where you left it with all the geometry intact.
Select the pommel, leg, and foot components and use the Move Tool to copy them and move them to one side. Choose the Scale Tool and scale the selected copies up by a factor of 100. Use the Zoom Extents Tool as needed so you can see the large copies of the components. Turn off the visibility for the Leg and Pommel layers.
Figure 10. Begin with the foot to extrude the parts of the leg. Use the Follow Me Tool to make the parts round.
Extrude the foot
Open the foot component for editing. Select the edge of the circle, choose the Follow Me Tool, and click on the foot profile to extrude it (see Figure 10). Correct the face orientation if necessary to get the white, front face color on the outside. (Go to Edit > Component > Reverse Faces) With the Select Tool, double-click on the top face. Use the TIG-weld extension to join the segments of the edge into a single continuous line. Use the Push/Pull Tool to pull the top face up at least 50". Soften the edges as needed and delete the top face. It’s not needed. Delete the circle for the Follow Me path. Click in space to close the foot component, and turn off the visibility for the Foot layer.
Figure 11. Delete the top face of the tapered portion as well as the circular face at the bottom.
Extrude the leg
Turn on the Leg layer and open the leg component for editing. Run a Follow Me routine and correct the face orientation if necessary.
Delete the face on the top of the leg section, as shown in Figure 11, as well as the cylindrical surface and bottom face at the bottom of the leg. Also delete the circular path for Follow Me and the line segment at the bottom.
Intersect and trim
Begin by turning on the Pommel layer. Open the Pommel component for editing. Triple-click on a face with the Select Ctrl to choose all the geometry. Go to Edit > Copy or press Ctrl-C (Command-C on the Mac) to copy the geometry to the clipboard. Click in space to close the Pommel component; turn off the visibility for its layer.
(As an alternative, you could explode the Pommel component, select all the geometry, and use Edit > Cut instead of Copy. I chose to copy the geometry because that leaves me with the pommel component intact in case I need it or in case things go pear-shaped.) Open the leg component for editing and use Edit > Paste In Place to restore the pommel geometry.
Keep the pommel geometry selected. Hold Ctrl (Option on the Mac) and select the inverted bell shape of the pommel transition (see Figure 12). Right-click on the selected faces and choose Intersect Faces > With Selection. After SketchUp completes the intersection, you will see edges where the faces cross. Use the Select and Eraser Tools to delete unneeded surfaces and edges. That should leave you with a pommel transition like the one shown in Figure 13.
Figure 12. Select pommel geometry and curved face, then intersect them.
Figure 13. Erase the waste to produce a smooth transition like this one.
Intersect and trim again
Repeat the process for the foot. Turn on the Foot layer, open the foot component for editing, and copy the geometry to the clipboard. Close the component, turn off the Foot layer, and open the leg component for editing. Paste the foot into the leg component using Edit > Paste In Place.
Figure 14. Select the faces shown here to check that the intersection command worked properly.
Select the surfaces of the leg and foot components, then go to Edit > Intersect Faces > With Selection to intersect the two.
After SketchUp completes the intersect operation, select the surfaces shown in Figure 14. If you get more faces selected, such as the surface of the leg above the foot, look closely for gaps in the lines at the intersection. If you find any gaps, there are a few ways you can try to remedy that. First, undo the surface selection and try scaling the model up even more than you already did. Try the Intersect Faces command again. You can also try manually tracing over the edges of the gaps to fill them in.
After deleting the waste, you should be left with the pad foot on the bottom of the leg (see Figure 15).
Finish the model
Click in space or hit Esc to close the leg component. Turn on the Foot and Pommel layers and zoom back so you can see everything. You no longer need the large copies of the leg, foot, and pommel components, so you can delete them all. Click on the Zoom Extents Tool to return to the original copy of the leg. Delete the pommel and foot components. Turn on the Setup layer and delete the drawing plane.
Figure 15. The completed foot. With all the waste removed, you can delete this scaled-up copy. The original will be identical.
Finally, do a bit of cleanup to get rid of unused layers and components. In the Layers window, click on the Details button, the arrow immediately above the Color column. Click on Purge. That should delete the Foot, Pommel, and Setup layers. Then go to the Components window and set it for the In Model library. Click on the house icon to the left of the search window. Open the Details window and choose Purge Unused. Your pad foot leg is now ready for use.
Check out Dave’s SketchUp Drawings Flickr album to see more of his work.