Thursday, September 24, 2020

Small Democratic Chair, Part 3: The Back and Finishing Up

Last time I ended up with the undercarriage and seat all glued up.  I had the hole locations for the back spindles in the seat all set, but I needed to see where they would go in the crest rail.  So I clamped the crest rail to the seat posts and laid the spindles where they looked right.

Spindles spaced to look good

The spindles tend to roll out of position when doing this, so rubber bands are your friends.  Here's one way to keep them in place.  I could have done the same with the crest rail too.

Rubber bands holding the spindles in place on the crest rail

I didn't get a picture of boring the 3/8" holes in the posts for the crest rail tenons, but the method is pretty cool.  With the crest rail clamped in place, just center the bit on the post and bore parallel to the rail.  It works great.

Crest rail tenoned into seat post mortises

Close-up of one side

To bore the holes in the crest rail for the spindles, I placed the posts and crest rail in position and sighted down to the seat spindle-hole locations.  The holes in the crest rail were bored only deep enough for the lead screw to poke through the other side.

Boring the hole for the right-most spindle

A simple technique I learned from one of Curtis Buchanan's videos was how to come back from the opposite side to complete the through holes.  He puts a dowel in the hole and uses it as a guide to line up the bit when boring in from the other side.  Simple, but genius.

Completing the through mortise from the underside using the dowel as a directional guide

Then, with those holes bored and the posts and crest rails back in position, I could bore the holes in the seat.  This might be the first time I've ever used the ratcheting feature of a hand brace.  But as seen in the next picture, I had to use the ratchet.  After putting the lead screw on the hole center, I sighted through the corresponding crest rail hole to get the proper angle.

Boring the spindle mortises in the seat

My view of same

And here's the back assembled for the first time.

Back assembled

After that, it was a matter of trimming the tenons so that just 1/8" or so protruded.  The tops of the posts were also cut to proper length and chamfered.  Then, I glued it up with wedges and hide glue, and when the glue had set, the tenons were rounded (or domed) to give them a nice look.

Tenons wedged and glued, ready for shaping a dome

After some sanding and scraping, I gave the chair a couple coats of BLO, which I thought brought out a nice color in the red alder.  And there she is.
Done and dusted

This was a really fun project.  I can't help wondering how different it would be if I could get some "green" oak for the legs, posts, crest rail and spindles, and a big plank of white pine for the seat, and a scorp and a ...  Oh well, until then I'll continue to make do with what I have.

Thursday, September 10, 2020

Small Democratic Chair, Part 2: Undercarriage and Seat Shaping

 To bore the leg holes in the seat, I used the usual method of aligning the bit to a sliding bevel and a combination square.  These two in combination get the right angle.

Boring a leg hole

Boring at this angle is a little awkward.  I would really prefer boring from the underside, but my layout points (from the drawing) were drawn for the top of the seat.

Legs fitted to the holes

No pics, but I tapered the holes with a reamer and tapered the leg tenons with a tapered tenon cutter - both homemade tools.

One of my favorite parts of making these chairs is building the undercarriage.  I didn't get any pictures in progress, but this uses the legs in situ to lay out the holes for the side stretchers and uses the side stretchers in situ to lay out for the center stretcher.  It's enjoyable to figure out how to bore the holes at the proper angles.

Undercarriage in place

Moving on: time to get to the crest rail.  Having no wood-bending capability, or access to green bendable wood, I found in my stash a piece of laminated beech that had a curve bandsawn into it.  It was almost the right curvature, so I cut off a 11/16" wide section and shaved it to 11/16" square and to the proper curve.  The curvature was laid out with homemade trammel points.

Beech about 1" thick by 2.5" wide

Now, it's 11/16" square (cross section) and octagonal layout lines have been added

Spokeshaved to octagonal

After boring the holes for the seat-back posts, I clamped the crest rail in place and played with different orientations of the spindles.  Curtis' full-size chair has five spindles, but I thought that would be a bit crowded in this smaller chair.

Three spindles
Four spindles (one still in rough form)

I liked the version with four spindles better.  Something else that makes sense to me is this.  With three spindles, there is one directly in the center of the back.  I'd prefer my backbone reside between two spindles.  Not that I'll be sitting in this chair, but still ...  But with that decided, I laid out the spindle hole locations in the seat.  The outside two used the original (five spindle design) hole locations.  The inside two were spaced evenly between the outer two.

Before going any further there, I had to get to the tough job of shaping the seat.  First I sawed to the outer shape and cleaned up to the lines.

Outer shape all set

Hollowing the seat was interesting.  Sure wish I had a scorp!  But a large gouge and mallet did most of the rough work.  First I drilled depth holes to ensure I didn't go too deeply or asymmetrically.  Unfortunately, I drilled some of these holes too deep and had to fill the holes later.

Hollowing out the seat

I tried to use the drawknife as much as possible to do the other shaping.  Good layout lines are key here.  Until I get a feel for this by making hundreds of chairs (not bloody likely!), good layout is the way to go.

Shaping the upper, side "flat" of the seat

Next I bored and tapered the holes in the seat for the back posts.  Also, the tenons of the posts were tapered for a nice tight fit.

Back posts fitted to the seat

At this point, I glued up the undercarriage.  Hide glue was used and the tops of the leg tenons were wedged.

Undercarriage glued up

Next time I'll get to the back assembly.  That was a lot of fun!

Thursday, September 3, 2020

Small Democratic Chair, Part 1: Scaling and Making Parts

 A couple months ago I bought the plans for Curtis Buchanan's democratic chair.  I like the simplicity of the design and easy-going nature of the chair.  But to start, I thought I'd make a 2/3rds scale chair.  This will be similar in size to the child's Sunday school chair I made a couple months ago.

The finished chair with new occupant

I don't have access to the kind of green wood Curtis uses for his chairs, so I'm making do with what I have.  And right now I have a bunch of red alder.  I'm also using cherry for the seat and beech for the crest rail.

The first thing to do was to determine the sizes of all parts for a two-thirds scale chair.  I made a (rough) Sketchup model of the full-sized chair and used the "scale" feature to get the size I was looking for.  Then I could simply take measurements from the model.  But I didn't go straight from the scale model.  There were parts I thought should be a little beefier and tenons that I thought were too small in the scaled-down model.

I started by squaring up parts, ready to shape.  Any parts thicker than 3/4" (such as the legs) are glued up from two pieces of wood.

The legs

From left: two seat posts, two stretchers, five spindles, two legs
Removing wood with planes to get square tapered cross sections on a side stretcher

Then it's on to the drawknife.  Lacking a shaving horse, the bench vise is used with a V-block and some leather to hold the part while shaving.
My view of the work holding setup
Using the drawknife

It's slower doing this in the bench vise, but you get used to it and after a while it goes reasonably quickly.  The wood not being rived and straight-grained presents problems.  On some parts the drawknife is cutting against the grain, even as the part is tapering to a thinner dimension.  I was careful not to pull off large chunks of the workpieces and at times had to push the drawknife or use a spokeshave.  But all-in-all, it went well.  Having a sharp drawknife is key here.

After getting the legs and stretchers to shape, I got to the seat.  As it happened, I had a cherry off-cut that was just the right size.

One problem though - a sizable crack

It didn't go all through the thickness, so I glued in a patch

Before I get into boring the holes for the legs, I wanted to write a little about scale drawings.  I couldn't just use the purchased plans to lay out the locations for boring.  I had to scale down the seat layout drawing first.  To do this, I copied the half-seat layout onto some easel pad paper that has 1" grid lines.  Then I drew a grid at 2/3 scale, where three grid squares is equal to two inches.  A pair of dividers helped, walking off three equal divisions in a 2" distance.  With the smaller grid drawn, I transferred enough points to draw my smaller half-seat.

Making the scaled-down half-seat drawing

If I could copy that onto transparency paper, that would make it easy to mark the seat blank.  But I had to draw the smaller grid onto the seat blank to make all the layout marks.

This pic is out of order, but you can see the grid drawn on the seat

All for now.  I'll talk about boring the holes and putting together the undercarriage next time.