Step 1: Materials
-jig saw or bandsaw with a tiltable table.
-a plank of wood atleast a 1/2" thick
-a strong woodglue
Step 2: Measuring (ya Sometimes You Have To)
Begin by marking a center line down the middle of your plank of wood, then mark the middle of this line, this is where you will put your compass.
Then mark in even increments along this center line, these will make up the rings of your bowl. The distance between lines is up to you, If you make the distance the same the as the thickness of the plank then there will be no "steps" in your bowl. I chose to have small 1/8" steps in my bowl because I think it looks quite interesting. This made my lines a little less than 1" apart . I drew six lines, the biggest being about 14" from the center and the smallest being about 8".
Now take your compass and seat it securely into the center mark you want it to stay here for all the circles you draw so they are all perfectly concentric. Then use it to trace out circles that meet all the lines you just drew.
Step 3: Cutting Down the Middle
At this point Id like to mention this method is not ideal when making a bowl like this, the best way would be to cut a board in half before drawing any lines a make a nice dovetail or other joint the hold the two boards together. This way there a much stronger joint holding the rings together, however I do not have the means to make a dovetail joint so I just butt jointed the rings together.
Anyway, I chose to use the jigsaw to make this cut because of the very thin blade, the only problem doing this is you have to be careful to cut a straight line, which is harder on the jigsaw.
Step 4: The Outer Ring
Step 5: The Inner Rings
By cutting the rings at angles it allows them to be stacked on top of each other, giving you a good surface to glue between rings.I set my table to about 45 degrees.
To cut at an angle simply tilt the table on your saw, the angle of this cut affects the angle of the sides of your bowl. However rember if you change the angle to something other than 45 degrees it will change how well the rings fit onto eachother. You have to do a little trigonometry (yikes high school math) you have to make the distance between rings bigger if you use a larger angle.
Step 6: Glue the Rings
This is pretty straight forward, just apply glue to both ends and press them together, for a stronger joint you could clamp it either with a circular clamp or with just use rubberbands, I didnt feel it needed it and my bowl has held up fine.
I just put a large glob of glue on a plank of wood and dipped the ends of the ring in that. Put down some wax paper so the rings dont stick to the table.
Step 7: Stack the Rings
This step was made slightly more difficult because there was still varnish on my plank of wood so I had to sand the tops and bottom of each ring so the glue would adhere properly, this could have been avoided either by using a virgin plank or sanding before drawing my lines.
note the spiral pattern formed by the joints.
Step 8: Waiting
I find that a couple episodes of top gear, a bowl of ice cream, and of course browsing instructables are great ways to pass the time.
Step 9: Enjoy or Finish on the Lathe
I chose to just smooth the outside on the lathe as this was going to be a bowl for bird seed and you would only really see the outside.