The plan for the headrest calls for a 29.5” radius. Hal likes to orient the grain vertically so as to flow with the rest of the chair – which I agree adds to the elegance of his design. To do this, I coopered the headrest using six billets, each 4” wide.
Once the billets were laid out, I cut each edge at 4 degrees. Four degrees on each joint edge * 10 edges equals the 40 degree sweep between each of the back legs (remember the inside edge of the each back leg was cut at 20 degrees).
I used clamps to glue the billets up in sets of two.
But, the curve became too large to use clamps to glue the final two joints. Hal introduced me to “Pinch Dogs” in his book. These worked really well to clamp the inner glue joints. They’re wider at the bottom than they are at the top, so as you pound them into the wood, they pinch the joint. They do mar the wood pretty significantly though. I think they left something like 0.5” holes in the wood. But, I cut out those holes when I cut the radius in the top and bottom of the headrest.
After glue up:
Next, I cut the front and back faces of the headrest. I had to add a riser block to my bandsaw to accomplish this. The headrest is 9” tall at this point if I remember correctly:
Sand, sand, sand. Hal suggested I recruit my wife for this operation. That didnt go well for me.
After sanding. You can see the dog holes in the top still:
Now, I need to cut the edges of the headrest at 6 degrees to match the 6 degree pitch of the back legs. I made very thin progressive cuts until the headrest fit snugly between the legs.
All that was left to do on the headrest was cut the 41” radius on the top and bottom and drill the holes for the back braces. I dont have a photo of that process, but here is the final result (I also happen to be attaching the arm in this photo).
-- Marshall - http://mcomisar.tumblr.com