Creating Turned Models with SketchUp
Part 2
By Sean Headrick
San Jose, California
In last month's article, you saw how to use SketchUp to model a turned bowl and then use that model
to create a a template to use when turning on the lathe. [I am aware that there are instances where
the print out dosen't come out as expected. Sometimes the model would print over several pages even
when the print settings are set to print to scale on a single page. The issue seems to be random and
despite searching for a reason for this problem, I could not find an explanation.]
This month you will learn how to modify your design by adding feet and handles and alter the
proportions to find a design that is just what you imagined. I will also start a new monthly feature
in this article explaining a tool or technique. This month we will take a look at Hidden Geometry.
Basically all the geometry in a SketchUp model is comprised of flat faces, so when you create a
curved face, it is actually made up of a bunch of polygons. Most of these edges are hidden so give
the illusion of a curved face. By choosing
VIEW>Hidden Geometry
you are able to see all these edges
Furthermore you can select the individual faces and modify them with the move, scale,
push/pull, or any other modifier tools.
If you would like, you can download the completed model from last months article
here
. First we
are going to see how you can erase sections of the bottom ring on the bowl to create individual
feet. This process is similar to the way you would sculpt a turned piece to create feet. Start by
enabling the hidden geometry view of your model.
The standard circle is made up of 24 sides – you
will want to
keep this in mind when dividing the ring into sections. I am making two feet on each side of my bowl,
so I begin by erasing portions of the bottom and leave behind only the sections that make up the feet.
You will probably find the undo button (or Ctrl-Z) very handy during this stage as it is
easy to accidentally erase parts you need.
You will notice that the faces made up of the edges you
erased are now gone. To reestablish the faces, use the pencil tool to reconnect the edges you erased.
Being able to see the hidden geometry in your model makes this step easier. Once you have
reestablished the faces, you will want to hide the edges you drew in. To hide edges or lines in your
model, hold down the shift key while clicking on the lines using the "erase" tool.
Adding a lid is basically the same process as making the bowl itself. First you will want to make
your bowl a group. This is a locked set of geometry that is grouped together and can be moved as a
group. This is a technique you will want to use often to keep different parts of your model separate
from one another. To make the bowl a group, triple click on the bowl. All the geometry of the bowl
should be selected. Right click on the bowl, and click "Make Group" from the drop down menu.
To make a lid, start by creating a construction guide at the center of the bowl's diameter. If
you are not yet familiar with construction guides, as a woodworker or designer, you should learn how
to use them. A construction guide is simply a temporary line by which you define a distance. By
choosing the tape measure tool either from your tools menu or from your toolbar, click one time on
the blue axis or any vertical line in your model, then click a second time at the center of your
bowl. You may have a problem finding the center point of your bowl. Use the tape measure tool to
create two construction guides. Click once on a point on one side of the base, then click a second
time on an opposing point on the opposite side. Repeat this process so the two guides cross. You
will end up with an "X" where the two lines intersect, indicating the center point of the bowl.
Now that you have a center line, follow the same steps to create a lid. Start by drawing a
rectangle you will use to draw your lid profile on. You will probably find it easiest to use the
"pencil" tool for this step, inferring to the red and blue axis to draw a rectangle with the bottom
edge sitting on the lip of your bowl. Draw the profile of your lid to fit onto the bowl. Next draw a
circle that will be the path that your "follow me" tool will use. Erase the rest of the face you
drew the lid profile on. Select the circle for your path. Using the "follow me" tool, click on the
profile of the lid to finish the process.
Assuming everything worked as expected you, should now have a snug-fitting lid for your bowl. You
should go ahead and select the lid by triple clicking on it and making it a group.
Once you have gotten to this point in your model, you could explore some variations to your design
using the "scale" tool. Click once on the bowl to select the group. Choose the scale tool from
TOOLS>Scale
or just use the "S" key on your keyboard as a shortcut. Learning the shortcuts to your
frequently-used tools can really increase your efficiency when modeling. If there is not a shortcut
for one of the tools, you can program your own in
WINDOWS>Preferences>Shortcuts
.
Using the different
grips, you can scale your model in different ways. Try grabbing the grip in the top center and
lifting it up a few inches. You will want to raise your lid in the blue axis out of the way first.
Try moving a few of the grips to see how it affects the model. Using the "shift" key with the scale tool
makes the scaling uniform. In other words the whole thing gets bigger. The "control" key makes the
scaling occur from the center as opposed to the opposite side.
To finish I want to show you how to modify the bowl by adding handles. While there are many ways
to do this, we are going to use the "move" tool to move a few sections of the bowl's surface out from
the body. I would like to take a moment to explain two ways to use this tool.
The first, choosing
the "move" tool from your tools menu or selecting it from your toolbar, you can hover over a group,
component or geometry. As you do, those parts will be selected and you can move them by clicking
once to move and clicking again to finish the move. Another way, which I prefer, is to select the
geometry first and then use the move tool along the direction you want the movement to occur. For
example, select the lid and then use the move tool along the blue axis or any vertical line in your
model to move your lid in the blue axis direction. You can also enter a value and click enter to
move that distance. NOTE: Any time you use a tool you can immediatly input a value for that tool and
hit "enter" (i.e. line = length, circle = radius, move = distance, polygon = sides)
To make the handles, start by double clicking the bowl. This will open the group for editing. You
should notice the rest of the model is faded out. You will need to have the hidden geometry enabled
for this step. Now select the faces that will make up the handle. You will want to create a
construction guide perpendicular to the faces you selected so you can pull the handle out from the
face. With the sections selected, use your move tool along the guide you created. Enter a value for
the distance. Entering a value here will let you make your handles uniform. You can continue to
select edges and faces of your handles , moving them around to fine tune the shape of your handles.
Don't hesitate to try anything. That's what the "undo" button is for.
Next month, whether your shop space is the spare bedroom or the perfect warehouse space, we will
explore some techniques for laying out an efficient work space using SketchUp and the wealth of
power tools, work benches, and just about anything else you could want from the 3D Warehouse. We
will even set up a vacuum system.
Sean Headrick, a former Atlantan once seen frequently at Highland Woodworking, now lives
in San Jose, California where he does woodworking and design.
His website is
www.headrickdesigngroup.com
.
Sean was
interviewed by Wood News
in 2007.
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