Making a Schwarz "Short Back" Chair, Part 8

This post is about making and fitting the comb.  I had been thinking about the comb during the entire project.  How would I get the right curvature?  How would I bore the holes at the proper angles?  The answers came eventually.

To get the curvature of the comb, I traced the tops of the long sticks onto a board.  Then used both geometry/trigonometry and a compass to figure out the comb's radius.

Tracing the stick tops onto a board

Drew the shape of the comb to get some dimensions.
The stick tops had about a 15 inch radius.

I verified that the angles (resultant angles, that is) of the sticks above the arm bow were the same as below that I had measured earlier.  Then I laminated some poplar to make a 2 1/4" tall comb piece.  The shaping of the comb was quite laborious and challenging.

I drew the shape on the blank, and made a quick change to offset
the hole centers slightly towards the inside curve

Shaped the inside curve with stopped saw cuts and chisel to remove the bulk of
 the waste.  Then the compass plane, spokeshave and scrapers smoothed the surface.

For the outside curve, most of the waste was sawn away, then
the rest was chiseled and planed smooth

Here's the curved part, with the front face marked out for a big chamfer

Boring the holes for the sticks took some thinking and creative work.  First, I leveled the chair on the floor and leveled the comb on the workbench.  With this, I could use a square behind the comb to find the angles at which the sticks enter the comb.  Then boring the holes was another matter.  In the pics below, you'll see the setup - it's pretty silly, but it worked.

A pair of levels made sure the chair was level side-side and front-back.
Wedges under the feet are your friends.  I also leveled the board on which the comb is sitting

There's a square beyond the comb and I moved it until it lined up with the stick.
Then I drew a line on the comb along the stick to give the angle it enters the comb.

There's a lot going on in this photo.  Read below.

In the photo above, the comb is held in the vise.  A straightedge is clamped to the comb, in line with the line drawn per the previous photo.  There's a bevel gauge set to the proper angle (about 16-17 deg.) clamped to the front vise chop.  A mirror is set up on a tripod for me to line up the brace and 1/2" bit with that bevel gauge.  It doesn't look like it in the photo due to the angles involved, but the brace is also in line with the straightedge.

Remarkably, after boring the six holes, a first fitting was successful.  After that, the final shaping of the comb was completed.  That included an angle on the front face, matching the angle of the sticks, and a 10 deg. angle top to bottom at the ends of the comb.

Comb fitted onto the back sticks

Shaping the angled front of the comb with saw, chisel and hammer,
spokeshaves and scrapers

And finally it's glued onto the sticks

This shows some of the detail of the comb

The sticks were pegged into the comb from the rear with
wooden chopsticks that I thinned down to 5/32"

For a finish, I used milk paint.  But first, I cleaned up any glue squeeze-out and gave the chair a good scraping and sanding.  Then I wetted it with a damp cloth to raise the grain and sanded again when dry.

Two coats of milk paint were applied on consecutive days, "sanding" with a green Scotch-brite pad after each had dried.  Finally, I added two coats of BLO on consecutive days and a week later a coat of paste wax.  I really don't like using BLO these days.  It stinks and I don't care to be exposed to the heavy metal driers that they use.  I had thought of using some water-based polyurethane, but last time I tried that it dried too fast for me to be able to wipe off the excess effectively.

The finished chair looks great.  It's not as comfy as I'd hoped, but I still like it.  Maybe there's another stick chair in my future.

The completed chair

Another angle

Now it's on to rehabbing some old tools I've acquired.  I'll write about them later.