Making a Schwarz "Short Back" Chair, Part 5

It was finally time to do the part that made me fairly nervous - boring the holes through the arm bow and into the seat.  I recently bought an 18" auger bit extension, and it might have made boring the seat holes a breeze, but it didn't fit through the 5/8" holes in the arm bow.  So I was left with the method I tried with the prototype arm bow.

Boring the first hole, using the alignment stick I made

The alignment stick is two pieces glued to a straight stick, one is 5/16" wider than the other.
The pointed end (left) goes into the seat hole location.
The upper end (at right) rests against and guides the auger bit.

Here's the upper end guiding the auger bit

When that hole was completed, I looked through the hole to see if it was pointing in the right direction.  It felt good, so I bored the rest of the holes.

If you blow up this picture, you see a pencil tip pointing to the seat hole location.

Now came another interesting part.  I had to figure out how to bore the hole in the seat at the exact angle as the corresponding arm bow hole.  As I mentioned, I didn't have an extension that would fit through the arm bow hole.  Here's what I came up with.

A straight 1/2" stick with a point at the bottom end and a few wraps of tape to make
it a good fit in the 5/8" arm bow hole.  The stick has a lengthwise line drawn on it.

I moved a square around the seat until it lined up with the line on the stick.

Then connected the seat hole location with the square to get the sightline. 

Along that sightline, I measured the resultant angle of the stick ...

... and marked it down on the seat by each hole location

Then I bored the holes with the help of a mirror, a square and the bevel gauge

Here's the seat with all stick holes bored, showing all the sightlines too

A first fitting of the sticks into their holes, sans arm bow

When I fitted the sticks in both the arm bow and seat, I found some misalignment in a few sticks.  I used a small rasp to widen the bottom of a few holes in the arm bow to give those sticks some wiggle room, and that helped get the sticks seated in their holes.

The arm bow is out of the picture here, but the sticks are in their arm bow holes.
The pencil is pointing to a stick that isn't pointing well to it's seat hole.

So I relieved a little material in the underside of the arm bow hole to
allow that stick to move left and back.

After a few iterations of this, all sticks fit in the seat and arm bow

Next time I'll get into making the undercarriage.