This instructable will show you how to design, laser cut, and build a stacked bowl quickly and easily. These bowls waste very little material during manufacturing. They can be made from a variety of matrials like: plywood, solid wood, and acrylic. The instructions assume that you have CorelDraw available to use. I'm using version 14, but most any recent version should work fine. You can also use other drawing software, but the process of creating the concentric rings may not be as easy.
You can find pictures of a variety of bowls that I have made at http://www.flickr.com/photos/tinkerology/sets/72157630041137092/
Supplies and Materials
Plywood to laser cut (size depends on your design and laser cutter)
CA Glue (http://www.amazon.com/CA-Adhesive-Thin-4-oz/dp/B001I9R0ZK)
Thanks and Acknowledgement
Special thanks to Mark Plaga (@mark_in_raleigh) for helping me learn to use the blend tool in CorelDraw.
Thanks also to Todd Hartzell for teaching me about CA glue wicking.
And finally, thanks to the wonderful staff at TechShop in Raleigh, where I do all my laser cutting.
Step 1: Draw a Polygon
Draw a polygon. I chose a pentagon since it is easy to work with a smaller number of points to deal with when you are just getting started. This will serve as the base shape for our bowl, but you will be able to modify it later to suit your taste. It doesn't matter what the size is, we'll change that it in the next step.
Step 2: Resize the Polygon
Select the polygon. Go to Arrange->Transformations->Size and change the size to 3.0 inches in both directions. Click Apply. You can also bring this window up by selecting Windows->Dockers->Transformations->Size (ALT+F10). This docking window will allow you to quickly change the size of the object and/or create duplicate shapes of varying sizes.
Step 3: Convert Polygon to Curve
Select the polygon again. Select Arrange->Convert to Curves. Then, select Shape Tool (F10). Select all points in the curve with a lasso rectangle. Click on "Convert Line to Curve" in toolbar.
Step 4: Make the Curves Smooth
Click on "Make node smooth" in toolbar. Now we have the basic shape which we can modify to create an interesting bowl. If you want to draw simpler shapes like circles or simple polygons, you can skip some of these steps.
Step 5: Resize the Shape
Select the shape. Select Windows->Dockers->Transformations->Size (ALT+F10). This will bring up the docking window which will allow you to quickly change the size of the object and/or create duplicate shapes of varying sizes. Make sure the size is a round number in increments of .5". So, say your shape is 3.04" by 2.56", you should change it to 3.0" by 3.0". This is not absolutely necessary, but it makes the math a lot easier when you are sizing all the layers of the bowl. Verify you still like the shape. If not, tweak the shape or size until you do.
Step 6: Copy the Shape
Copy the shape and move it beside the original shape. Give a good bit of spacing so that you can create several concentric rings around the shapes.
Step 7: Offset the Sizes of the Shapes
Select the copy of the original shape. Make sure "Non-proportional" is checked in the dock. Add .25" to width and height and select "Apply"
Step 8: Create the Outer Ring
Now select the copy of the original shape. Increment width and height by 5" and select "apply to duplicate". Select the 3.25" and the 8.25" shapes that you just made (leaving the original unselected). Now you have two concentric shapes which you can blend together with appropriately sized shapes between them.
Select Effects->Blend. This will bring up the Blend dock which allows you to blend two shapes. Change the number of steps to 9 (8.25"-3.25"=5"; 5"/.5"=10; 10-1=9). This will create 9 steps shapes between the two selected shapes. Press Apply. Now, you have 11 concentric shapes evenly spaced between 3.25" and 8.25".
Step 10: Create the Other Outer Ring
Select the original shape. Then, increment width and height by 5" in the Transformation dock and select "Apply To Duplicate". Select the 3" and the 8" shapes that you just made. Now you have two concentric shapes which you can blend together with appropriately sized shapes between them.
Step 11: Blend to Make Concentric Rings
Go to the Blend dock. Change the number of steps to 9 (8"-3"=5"; 5"/.5"=10; 10-1=9). This will create 9 steps shapes between the two selected shapes. Press Apply. Now move the sets of shapes to the upper left corner of your document, leaving only a little bit of space between them.
Step 12: Prepare the Laser Cutting
Select all objects. Go to Object properties. Set the line width to hairline and color to red. Hairline width tells the Epilog laser cutter driver I use to cut that part of the design. If your laser cutter needs something else, do the right thing. I change the color to red on hairline width lines so that I know I've set them up correctly.
Save your design.
Now you are ready to laser cut your shapes!
Step 13: Stack Up the Laser Cut Pieces
Stack up the laser cut rings starting with the largest and working to the smallest. Align the rings so that they leave a symmetric border around the outside of the ring. You can put whichever side you like down depending on how you want the bowl to look. In general, I prefer to have the top of the laser cut rings stacked down so that the smokey side of the wood shows from the top of the bowl. You can stack one or both of the inner pieces of the ring as the base.
Step 14: Glue the Bowl Together
Once you have the rings and bases all stacked up and aligned how you like them, you'll want to glue them up. Use the CA glue referenced in the first step and place as small a drop as possible in the corner of each ring in a line going top to bottom. Press down slightly on the base of the bowl to compress the rings as you do this and hold for 30 seconds or so at the end. If you have a small weight that will fit on the base of the bowl, you may want to use that.
Then, repeat the drops in the corners of the bowl for several points around the perimeter of the bowl. Give the glue some time to set up and you are done!
Once you get comfortable with the process, you can make all kinds of bowls, jugs, urns, etc...
Step 15: Finished Bowl
Here's one of my favorite bowls. I like the shape and size of the bowl. It's large enough to hold fruit or other substantial items.