Teaching-It Ain't Easy
I’ve taught some woodturning classes over the last few years with mixed results. I don’t do it for the money (I don’t charge nearly enough)! I teach to help shorten the learning curve of my students. I teach to pass on what I have learned from many years of turning and from instruction by the best turners in the world.
The crux of my lessons is about how form (shape) affects beauty. I teach my students to use organic shapes, shapes that appear in nature, because those shapes are pleasing to the eye. My favorite bowl shape is the catenary curve. It is the shape a chain takes when suspended between two fixed points. Below is an example.
By Kamel15 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5609313
To help visualize this shape in bowl turning, I use a ball chain. Ball chains were used on old light fixtures, ceiling fans and rabbits feet. They can be purchased online or at hobby shops, for example. If I have a turning blank that is 8” in diameter and 3” thick, I draw a 3” by 8” rectangle on a sheet of paper and tape it to the wall. I hold the chain at the top points of the rectangle and shorten the chain until the curve of the chain grazes the bottom line. That is the shape of the catenary curve for that particular bowl blank. This visualization helps me transfer that curve when shaping the blank on the lathe.
Catenary curve with ball chain.
Besides being pleasing to the eye this shape is easier to turn. There are no abrupt changes in direction and no flat surfaces. It is a pleasant, flowing arc. You can take one long, shallow finish push-cut with an Ellsworth gouge and produce a very smooth surface. Below are some recent examples of my bowls with good catenary curves.
Wild Black Cherry Wooden Bowl #1948
Tulip Poplar Wooden Bowl #1833
Sycamore Wooden Salad Bowl #1915
Below is an example of an early bowl I turned. The shape is clunky, the lines do not flow. The wood is pretty, the bowl is not.
If you take a class from me I will try to teach you to make bowls with pleasing lines. I will give you tools (ball chain) and encourage you to really look at nature for inspiration, the rest is up to you.