Mankind is not a circle with a single center but an ellipse with two focal points of which facts are one and ideas the other. –Victor Hugo
An ellipse is an endlessly adaptable shape that is beautiful and easy to lay out. It is one form that I often come back to, even though I draw many other types of outlines for bowl hollows. You can’t go wrong with an ellipse.
There are many ways to lay out an ellipse, featuring all sorts of devices. This one is simple and effective. It allows you to form the perfect size ellipse for the log before you. You decide whatever length and width you want the ellipse to be, and that ellipse will be formed with no guesswork. Plus, it works on rounded surfaces (like the top of a bowl done “upside down” style).
This is the method I use in this video , but I’ve broken down and explained the steps more clearly in the photo sequence below. I am demonstrating on a pine board, but imagine the surface is the top of your bowl blank.
It all starts with compasses. These are essential and versatile layout tools, not just for this type of work. For bowl layout, I always use the ones that can hold a pencil. In Peter Follansbee’s historical furniture work, he uses pencil-less compasses, sometimes called dividers. Here is one of his blog posts referencing the historical use of the compass.
The two compasses on the left are from Lee Valley Tools. For larger bowls, they come in very handy. The other two are yard sale finds.
Draw a lengthwise center line from end to end. Place the point of the compass just inside the end of the log at one end of the line. Open the compass a little beyond what looks to be the center and strike an arc. Repeat from the other end.
With a ruler (a flexible ruler if working on a rounded surface) strike a line through the intersections of the arcs. The line formed is not only centered, but also perpendicular to the lengthwise center line.
Decide (up to you, the designer) how long you would like the hollow portion of the bowl to be (i.e. how much left on the ends for handles). With the point of the compass in the center, strike a mark at that distance to both sides. They are equidistant from the center.
Decide how wide you would like the hollow to be, and repeat the procedure in the previous step, this time for width.
Set the compass back to one half the length. (Or I guess you could reverse the last two procedures if you prefer.)
Keep that compass setting (one half of the length), place the point of the compass where the width mark intersects the vertical center line, and strike an arc at the two spots it crosses the horizontal center line. Repeat from the opposite side if you want to be sure.
Drive a small brad in at at outward angle at the two focal points you have located.
Wrap a string around the nails to form a triangle with its apex at the widest point of the ellipse. Form a simple overhand knot…
…then secure it like this.
By tugging on the strings here and there, you can adjust the knot to end up with things just right.
Place a pencil within the ring of string, and, with a little outward pressure, let it guide you to form a beautiful ellipse.
Now you have an ellipse that is just the right length and width.
These are two books that include practical exercises for using compasses to generate all sorts of shapes and lines, plus lots of related ideas. By Hand and Eye is full of all sorts of design ideas — published by Lost Art Press.
My sample board was dry, but normally I am working with green (wet) wood. I find that watercolor pencils are excellent for marking on it. There is no need to purchase the more expensive brands.