Introduction: Scroll Sawed Wooden Bowls!

Hey everybody!

I was disappointed recently to find that there are no instructables on making wooden bowls with a scroll saw, even though there are lots of books published on the subject.  So I've decided to fill the gap.

All you'll need is a scroll saw and a few other tools to get started.  I like this project because it minimizes the amount of wasted wood (unlike bowls made with a lathe) and the bowls produced have very interesting designs.  It's also surprisingly easy, as long as you have the patience to sand it to perfection...  So let's get started!

I also wanted to thank my wife Trish, who inspired and helped me to tackle this project.

Step 1: Materials

The following tools are mandatory:
These tools are optional, but make everything easier and improve the quality of the bowls:
You will also need the following supplies:
  • Wood glue
  • Scroll saw blades (yes - they will break often)
  • Pen/pencil
  • Clamps, clamps, and more clamps
  • Sand paper and sand paper belts for sanders
  • Varnish (and/or stain, depending on what you want to do)
  • At least 1 board foot of wood, can be pieces of various woods
Note:  If you plan on putting food in the bowl, you should avoid using exotic hardwoods.  Many of those woods contain toxic chemicals which can contaminate food and possibly harm you.  However, most domestic hardwoods are fine for use with food.

Step 2: Wood & Laminates

The first step is to prepare the blank from which you will cut the bowl pieces.  I recommend making the blank at least 12"x12".  It can be a solid piece of wood or a laminate of several different types of wood.  If you use more pieces with contrasting colors, it makes the final design on the bowl much more impressive.  I used a parallel laminate of 3 types of wood for this project, but you can do far more just by changing the thickness of the strips or gluing them together at different angles.

Here are the general steps for making a good laminate:
  1. Cut the desired strips to the desired width with a table saw
  2. Use a miter saw to cut the strips to the desired length
  3. Use a jointer to smooth and level the sides of the strips
  4. Fit the pieces together to make sure there are no gaps

Step 3: Gluing the Laminate

Special care must be taken while gluing the strips of the laminate together to avoid warping. 
  1. Choose a flat surface that you can use clamps with and clean it
  2. Look ahead to step 7 before gluing
  3. Apply a good amount of glue to each piece and join them together. Do not glue the middle two pieces together if you want to avoid drilling entry holes, as mentioned in step 7.
  4. Carefully wipe up excess glue
  5. Use long clamps to squeeze the pieces together
  6. Use more clamps to keep the laminate flat on the table/surface
  7. Wipe up any more excess glue
  8. Let the glue dry for about 24 hours at or above 55F

Step 4: Finishing the Laminate

  1. I highly recommend using a planer to smooth the laminate and get rid of any warping that may have occurred during gluing. 
  2. Once you have smooth surfaces on both sides of the laminate, measure its thickness at multiple points to make sure the piece is even.

Step 5: Choosing Bowl Dimensions

The simplest way to make a bowl is to cut the rings at a 45 degree angle.  That way, the rings are as far apart as the laminate is thick (see picture below).  I recommend the diameter of the inner circle be at least 3".

If you want to try different dimensions to make unique bowls, grab a calculator or open up excel and follow the steps below (see second picture):
  1. Choose a diameter for the inner circle (should be 3-4")......D, cell A2
  2. Measure the maximum length/diameter of the laminate.....L, cell B2
  3. Measure the thickness of the laminate...................................T, cell C2
  4. Choose an angle to cut..............................................................(theta), cell D2
  5. Calculate width of each ring......................................................X, cell E2
  6. Cut and paste this formula into cell E2:           =TAN(RADIANS(D2))*C2
  7. Calculate the number of rings (round down).........................N, cell F2
  8. Cut and paste this formula into cell F2:           =FLOOR((B2-A2)/(2*E2),1)
  9. Calculate the final height of the bowl.......................................H, cell G2
  10. Cut and paste this formula into cell G2:          =(F2+1)*C2
  11. Play around with the cut angle (theta) until you are happy with the final height of the bowl.

Step 6: Trace the Circles

Once you have calculated the width of each ring (X from last step), you will need to trace the rings onto the bowl, like so:
  1. Find the center of the blank and mark it with an X.
  2. Take a stiff piece of card stock (ex: cover of a notebook or holiday card) and cut a 1" wide by 6-12" long strip.
  3. On one end of the strip, make a tiny hole with the point of a knife
  4. Draw a straight line from that hole across the length of the strip
  5. Make another hole about "D/2" inches along that line from the first hole
  6. Make more holes, each "X" inches apart, until you've reached the maximum radius of your bowl
  7. Pin the strip down to the blank with a pointy object and carefully trace concentric circles by rotating the strip around the centerpoint on the blank (see below)

Step 7: Optional: Drilling Entry Holes

Most traditional wood bowls start with a solid piece of wood.  To start cutting the rings, entry holes must be drilled at the same angle that will be used with the scroll saw to allow you to start cutting.  If you have a good drill press and a strong thin bit, you can use this method.

However, I don't have a good drill press, so I can't make consistent entry holes.  Therefore, I came up with a way to avoid having to drill them.  I simply make the laminate in even halves and cut semi-circles which are later glued together to give full circles.  That way I don't have to worry about the accuracy of entry holes or putting on/taking off my scroll saw blade.  See the second picture below to see exactly what I'm talking about.

Step 8: Cutting the Rings

Now it is time to warm up that scroll saw!

The method here is pretty self explanatory, just cut the rings out and take your time.  Here are some extra pointers:
  1. Make sure the stage on the scroll saw is adjusted to the proper angle.  Cut a test piece and measure the angle, if necessary.
  2. Go slowly, but never stop moving forward.  If you stop or go back, you will remove more wood and scar the bowl.
  3. Maintain lots of pressure on the piece for a clean, consistent, and quick cut

Step 9: Glue.

We're almost there!

Before you do any gluing, mark the pieces so you can glue them together exactly as they were cut.  If you forget to do this, some of the bands may not match up properly.

If you avoided drilling entry holes, the first thing to do now is to glue the half circles together to make full circles.  Use plenty of glue and clamp them down on a flat surface until dry.

Once you have the rings glued, glue them together, one at a time.  Make sure that the bands on the outside of the bowl line up as nicely as possible. 

If you have a spindle sander, don't glue the bottom piece onto the bowl just yet.  Leaving the bottom of the bowl open will allow you to easily sand the inside of the bowl using a spindle sander.  If you don't have a spindle sander, go ahead and glue the bottom piece.

Put the glued bowl onto a flat surface and compress it with something heavy.  Some people use "bowl presses" (google it), but I just use my old textbooks.  Compress the bowl for at least a few hours or until the glue has dried overnight.

Step 10: Sanding

No matter how good your cuts were, there's a lot of sanding to be done!

I prefer a belt sander for this step.  I smooth out the outside and inside of the bowl with about 50 grit sand paper, then move up to 120 grit to make it even smoother for finishing.  Examine the bowl carefully, rubbing your fingers across the joints to make sure they are as smooth as possible.

I also like to round off the edge of the bowl with my disc sander.  Just take your time and evenly sand the edge of the bowl.  Be careful not to lose control - disc sanders can quickly gouge your bowl.

Finally, I like to thoroughly sand the inside and outside of the bowl with 120 grit to get any small spots the belt sander may have missed.

Step 11: Finishing Touches

Once the bowl is smooth, wipe it down with a wet cloth to remove any dust particles.  Let it dry, then apply a 1-3 coats of varnish.  Smooth out/sand with high grit sandpaper as necessary.

Congratulations!  You made a bowl!

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