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.

Making a Schwarz "Short Back" Chair, Part 4

The trials with the prototype arm bow gave me some confidence in making the real arm bow.  I had originally drawn the arm bow on a big piece of paper, but I knew that wouldn't be good enough to cut out a template from.  So I went to the craft store and bought a $2 piece of thin translucent plastic that would be thick enough to use.  This was the first time I used this stuff and it worked well.  I drew the shape with a large homemade compass and a sharpie marker, then cut out the shape with scissors.

Two planks that will make the four pieces for the arm bow.
This used to be a cutting board that someone was getting rid of.
These started about 1 1/8" thick, planed down to 7/8".

Here's the template laid out on a blank.
The pencil is in the area marked out for the lap joint.

I cut the parts out a bit oversized for later trimming.
Here's the lower part of the arm bow ready to be half-lapped

And then the upper piece will be glued on

The lap joints came out good and tight and I got to use a plane that I bought early on in my hand tool life and rarely use - the shoulder plane.  A nice plane, but probably not one of my smarter purchases.

Marked the waste carefully to avoid mistakes

Squaring an end of the left arm and then of the center piece

Using that squared end to mark the half lap on the center piece

Then sawed away the waste ...

... and cleaned up the surface with router plane.
There's an off-cut supporting the cantilevered end of the router plane.

Using the shoulder plane to get a nice straight, square shoulder

Then, using the first half of the joint to mark for the second half 

  Gluing one of the half laps.  Note I didn't use the special clamp
blocks that I posted about earlier.  Rather, I just canted the clamps a bit
to help pull the joints tight.  It worked well enough.

And after planing the lap joints flush, here's gluing on the upper piece

After the glue dried, I shaved down to the lines and cleaned up the arm bow.  The next step is boring the holes in arm bow and seat, but I'll wait until next time to cover that.