This page was written in 1998 and titled "Designing the Weeks Rocker."
It lists our design criteria in general and has an example of their application.
I wanted to build a rocking chair in which:
Building for generations of use requires:
I wanted to build handmade rocking chairs:
After finding the curve for supporting the lumbar and upper back, I decided to use the lower muscles of the back as user supplied padding — two vertical muscles, therefore, two vertical splats. I tried two splats, each about the width of a lower back muscle, and the two about as far apart as those muscles are. I thought two might do, but a trial showed that more support was needed at the rib cage. We tried six, but there was no functional or visual benefit.
I settled on a 1/2" thickness for the splats, thick enough to be firm and supportive, thin enough to be light. A 2" thick piece of wood of at least 4" in width will make a blank from which splats can be efficiently cut. Selecting flat sawn wood for the blank, the growth rings will be perpendicular to the face of each splat. This is the strongest orientation of grain and displays the most pleasing lines in the overall composition of wood figure in the chair.
The drawings showed that a tangent to the back curve intersected the plane of the seat at 7-1/2 degrees and entered the crest rail (headrest) parallel to its face. To fix the splats at both places, I chose to mortise them deeply into their receiving parts. The splats were clunky looking so I tapered them--making them a quarter inch narrower at the bottom than the top.
I solved every problem similarly: draw, think, draw, try--rethink, redraw, retry, refine. I made a rocking chair. Many people sat. I made minor changes until I thought it was right. I knew it was right when I received a card (still have it) from Elizabeth F. who received number 6 as a gift. She wrote, "The rocking chair is a perfect blend of art and engineering."