An Introduction to Gothic Tracery (With a Router)
This week I’m finishing up work on an aumbry for a future issue of Popular Woodworking Magazine. More than anything, this project has been about exploring Gothic geometry. But as with any project, I always have a lot of detours and dead ends.
The pierced carvings on the front of the aumbry are fairly simple, yet I was afraid they would be off-putting for some beginning woodworkers. So I started investigating the amazing geometrical world of Gothic tracery. With a compass and a straightedge, you can draw almost anything in the Gothic lexicon.
I went a bit nuts with it for a couple days.
If you study the plates included with this entry, you can see how almost all of the Gothic forms flow from a square, circle or equilateral triangle. After drawing out several dozen lancet arches (easy), I decided to put a pierced form in the center of the door that is based on a triangle. You first draw the equilateral triangle on the work. Then you drill a hole at each vertex that has a diameter equal to each segment of the triangle.
(In English: drill a hole at each corner of the triangle. The bit’s diameter should be equal to the length of one of the legs of the triangle.)
The three holes end up tangent to one another – and a middle triangular section of waste falls away. Then you can shape the edges of the piercing with a router. I experimented with a bunch of bits to try to create different effects. The best was a small chamfer, which I guided with a bearing on the rim of the piercing.
After making a few test pieces, I made the piercing in the finished door of the aumbry. I took a step back and said to myself: It looks like a gambler’s door. The piercing looked too much like the suite of “clubs” in playing cards.
So I set the door aside and made all the pierced carvings the hard (but fun) way. With a chisel and rasp.
— Christopher Schwarz