Monday, March 28, 2016

Dining Chair - Part 4

When we last left our intrepid woodworker, the upper and lower backrest rails had been shaped and scraped.  However, he failed to put them together to see how close to the same profile they were.  Turns out that the upper rail needed just a little more material removed to match the lower rail.  This is important so that when the mortises are chopped, the slats will fit right.

The stock for the slats was still fairly rough, so I first looked at the chosen pieces.  One piece did not seem to look like the others, so I chucked it and found another that had similar quarter-sawn grain.
Center piece does not fit with others
This end grain shot shows that the middle board is not like the others and why it didn't look good with the others.
End grain shows why they don't look good together
This is better, though the way the light reflects makes it look sketchy.  They really looked much better in person.
The chosen ones
I planed one side flat, checking with winding sticks, then got the boards within a few 100ths of final thickness and let them sit for a while.  In the mean time I got to the layout of the mortises in the backrest rails.
Mortises laid out
Along the curved edge, I found a center "line" using a finger as a guide, referencing off the front concave surface.  Then added a line 3/16" forward of that.  Before shaping the rails, I had marked the center of the 13.5" length (excluding tenons) across the edge to be mortised.  That line is the center of the center slat mortise.  The extents of the slat and the extents of the tenon were marked using a small homemade wooden dovetail square.  And a 3/8" brass gauge block was used to mark the front and rear extents of the mortise.  The other mortises were marked similarly, leaving 1" between slats.

Well, when it came to chopping the mortises all was going well until I chopped one starting at the extent of the slat - not the extent of the tenon!  Arrgh.  I'm just going to leave it since the slat shoulder will cover the mistake.  And fortunately it's on the underside of the upper rail, so even if it was just barely visible, someone would have to work to see it.
Upper right mortise messed up
With the mortises chopped, I got back to the final dimensioning of the slats.  I'm making these 2 1/4" wide because I'm deviating from Paul Sellers' slat design.  I'm adding an "S" curve for visual interest.  It goes well with all the other curves on the final product, too.
Slat template and slats laid out
I ganged the slats together to mark the extents of the length of the slats.  Continued the knife lines all around, then deepened them and cut the shoulders.  The cheeks were either split or sawn and the router plane was used to fit the tenons to the mortises.  The sides of the tenons were trimmed until all fit together nicely.
Backrest dry-fit together
I had to trim the mortises' front wall (at the bottom) to get the slats to fit properly.  I can't use a mortising guide for these as I did for all the leg joinery.  When cutting the mortises, I used a small square to judge that I was chopping perpendicular to the rail, but I still needed to tweak it a bit to get it right.

All for today - tomorrow it's on to the side rails.  These are angled as the front of the chair is 3.5" wider than the back.  And the lower rail fits into the angled back leg, so we're talking compound angles.  It a challenge when you only have one bevel gauge and you need three!


  1. I liked the color difference in the middle rail but I like asymmetrical too. I have done that mortising boo-boo too. I now don't lay out for the full slat - I just do the actual mortise. It is way too easy as you chop several of these to miss that.

    1. Ralph - Glad to hear I'm not the only one chopping in the wrong place. Also glad I don't have to replace that part. There's a lot of work into it already.