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.

Making a Schwarz "Short Back" Chair, Part 7

Before shaping the seat, I made some plugs to fit into the leg holes so that I wouldn't blow out the hole rims when removing material for the saddling.

A redwood plug in a leg hole

Concentric semi-circles drawn and depths marked

Depth holes drilled (most of them) and spindle deck inner aspect defined

I kind of winged it when it came to mark the depth to which I wanted to excavate the seat.  It's based on things I've read and the few seats I've done before.  But it dives fairly quickly from the spindle deck - those first holes nearest the deck are 3/8" deep  - but then levels out at max depth of 1/2".  One thing I should note: I defined the inner aspect of the spindle deck with a knife, being careful not to stray from the line.  Then I used a router plane to create a little flat about 1/16 to 1/8" deep on the saddling side of that line.  I started the excavation about 3/8" from that line.

I still don't have a scorp, so I did the waste removal with a homemade compass plane (bottom curved in two directions) and a makeshift travisher.  I took a LOT of time to get to where it felt like there were no bumps.  Then I scraped and sanded until smooth.

Tools of excavation

This knot was a bear - right next to the spindle deck and leg hole

Getting close to the drilled depth holes

I had penciled in the bottoms of the depth holes for better visibility

And now scraped and sanded.  Also, removed the perimeter waste at back
with saws and chisels and then smoothed that rear edge with a #4.

Another view showing detail

Marked the edges all around for a chamfer on the underside.
Waste was removed using scrub plane and spokeshaves.

When the seat was finally done, I glued up the undercarriage.  I used white glue for the convenience, so I hope I never need to repair this chair.

Rails and stretcher glued, legs glued into seat and wedges tapped home

I let that dry before getting the upper part of the chair glued up.  After the glue had set, I removed the protruding leg nubs.  And man, it was a bear getting the leg tops flush with the seat.  I tried many different things - flush saw, gouges, chisels, scrapers.  I don't even remember what worked best - I just remember it was flippin' hard.  But we persevere and we get it done.

Next was gluing the upper part, sans comb - I left the comb for last.  But the spindles and arm bow went pretty well.  I had done several dry runs.  In the end, I couldn't get one of the long sticks all the way down into its seat mortise.  It was about 3/8" shy.  No problem though, I just trimmed 3/8" off the top and I'll never notice.

Arm bow set at proper height and wedges applied to the short sticks

You can tell the third long stick from the left is a little taller than the rest

Due to the flat surface of the arm bow, the short stick nubs were easy to 
remove with a flush cut saw, then trim level with a chisel

That's all for this post.  Next time I'll get into the comb.  It was a really challenging piece to make and to bore holes into.  Until then ...

Making a Schwarz "Short Back" Chair: Part 6

Time to get beck to the legs and undercarriage.  After making and reaming a couple test holes in the waste area of the seat, I bored the holes for the legs.  Both front and back legs had a 23 degree resultant angle, so I made a guide from a piece of scrap.

Guide block set on the sightline, guiding the auger bit angle

Before reaming the hole, I mark the far end in pencil to gauge progress

Reaming the hole with homemade reamer

Checking progress along sightline with a test stick - could go a tad to the right

And checking the resultant - bang on!

Then I used a homemade tapered tenon cutter to get the legs fitted into their tapered mortises.

Tapering the tenon of the first leg

Apparently I stopped taking pictures for a while, but the rest of the legs went just fine.  Next up was making the two front-to-back rails and the side-to-side stretcher.  For these I glued up some poplar to get 1 1/8" blanks.  After squaring up, I marked for planing down to about 3/4" at the ends.

Right: marked
Middle: tapered on two sides
Left: tapered on four sides

End view of above

Planing setup for getting to octagonal, then 16-sided

Top: octagonal
Middle: 16-sided
Bottom: tapered round

The parts scraped and sanded

To bore the holes in the legs, I used Curtis Buchanan's rubber band method to find the hole locations and angles.  He stretches a rubber band around the front and back leg, at the level that you want the rails and stretcher to be (for me, that was 11" from the seat bottom).  Not only will this rubber band give you the sightline for the hole, but also you can mark the hole location on the leg so it's centered (side to side) on the leg, relative to a line drawn from the other leg's hole.  Not sure if that made sense, but essentially you're trying to get the hole where there's the most leg meat.  As a bonus, when boring these holes, I finally got to use the auger bit extension that I recently got.

There's a sightline on the seat and I line up the bit and extension with it.
For the up-down alignment, I have a piece of tape on the combo square marking where
the center of the auger bit extension should be.

Here I'm making a straight 5/8" tenon on one of the rails

After both rails were fitted, I bored for the stretcher with the rails in place.

And the undercarriage is complete, just waiting for a later glue-up

A couple of details were not covered in pics.  I made the rails and stretcher about 3/32" longer than the measurement from mortise bottom to mortise bottom.  Adding a little extra to the rails and stretcher gives the undercarriage more rigidity because it puts the chair in tension when it's all together.  The lengths were obtained using two 1/2" diameter sticks, one in each 5/8" diameter mortise and each longer than half the total span, and marking on one stick where the other stick ends.  Then you can lay the sticks on the bench, lining up that mark, and measure the overall distance.  

Next time I'll get into shaping the seat and a partial glue-up.  I'm saving the comb for last - that was a whole story in itself!

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.