Lumber and Tools
White oak is a bargain compared to other rot-resistant hardwoods like teak and mahogany, and it’s readily available in a variety of thicknesses. We used 8/4 stock for the legs (wide boards so we didn’t have to glue up the blanks), 6/4 for the arms, rails and stretchers and 4/4 for the slats and tenon stock. For dimensional stability, we chose boards with straight grain. Each chair requires about 35 bd. ft. of lumber. We paid $160 per chair for our rough-sawn stock.
Routing all the mortises will give your plunge router a real workout. It must have a 1/2-in. collet, an edge guide, 2-1/8 in. of plunge capacity and the guts to plunge deep in white oak (at least 1-1/2 hp).
This project also requires a tablesaw and bandsaw, a drill press with a sanding drum and a router table. You’ll need 3/8-in. and 1/2-in. straight bits for mortising, a 2-in. flush-trim bit, a 1/4-in. round-over bit and a chamfering bit (see Sources, page 87). A jointer and planer are recommended, but not essential. You can have your stock milled to thickness at the lumberyard.
Squarely-cut blanks are essential for sound joinery and good results. Make sure your tablesaw’s miter gauge makes square crosscuts. The heavy leg blanks may require a crosscut sled or an accurate chop saw.
Use templates to duplicate the shaped legs, arms and seat rails (Fig. D - G, page 84). 1/2-in.-thick MDF is excellent template material (available at most home centers for $5 per 2-ft. x 4-ft. sheet).
Use layout marks to guarantee that mortises and adjoining pieces go where they’re supposed to go.
Plunge-rout the mortises, using a straight bit, an edge guide and clamped-on stop blocks. Mortises are either routed into the end grain using a jig, or into the long grain, using a flush-mounted support block.
Rout mortises before you cut profiles. It’s much easier to fit the angled joints around the mortises than vice-versa.
Always rout from the same face so all the mortises in each piece are consistently located, even if they aren’t perfectly centered. Then the joints will always line up. Simply mark all the edge-guide faces with arrows before you rout (Photo 3).
Make Templates for the Legs
Cut the leg templates from blanks that match the leg blanks (Fig. D). For the best results, saw straight portions of the templates on your tablesaw (Photo 1). Bandsaw curved shapes oversize and finish them using a sanding drum in your drill press.
To cut the back side of the back leg template on your tablesaw, you’ll have to make stopped cuts from each end. Finish by cutting the remaining middle section on your bandsaw. When you cut the inside edge of the front leg template, stop the tablesaw cut at the beginning of the curve and cut the rest on the bandsaw.
Mark the Leg Blanks
Before tracing the template profiles onto the leg blanks, make sure the template and blank are aligned. The front leg template (Fig. A, below, Part A, and Fig. E) is easy to position, but the only reference surfaces for the rear leg (Fig. A, Part B, and Fig. D) are at the middle of the front edge and on the bottom.
After tracing the profiles, clamp the front and back leg blanks together. Then mark the locations of the mortises and outside edges of the seat rail (C), side stretcher (D) and arm (E) on the front leg blanks (Photo 2).
Mortise the Back Leg Blanks
First, adjust your router’s edge guide to center the mortises on the edge of the blanks. Then rout mortises for the seat rails (Photo 3).
To rout mortises for the stretchers and arms, steps have to be cut to get the router close enough (Fig. B, below).
To create the steps, first make a stopped cut on the tablesaw (Photo 4). Finish cutting the remaining angled portion of the step on the bandsaw, making sure to stay on the outside of the line.
Extend the mortise layout lines onto the steps. Then rout 2-1/8-in.-deep mortises for the arms and stretchers (Photo 5).
Shape the Back Legs
First, rough-saw the back leg on your bandsaw to the outside edge of the pattern line. Then fasten the template with heavy-duty double-faced tape, making sure it’s flush with the leg at both the bottom and front edges.
Shaping the legs requires some routing against the grain, which can cause tear-out. For the best results, mount the template on the right side of the blank (when viewed from its front edge). This setup limits against-the-grain routing to the less-visible lower portion of the leg (Photo 6).
Finish the back legs by routing the mortises for the back assembly on their inside faces, using extensions to support the router. The extensions must be as thick as the leg and clamped in line with its edge (Photo 7 and Fig. K). Be sure to adjust your edge guide before routing.
Complete the Front Legs
First, rout centered mortises for the arms, using a jig (Photo 8 and Fig. C, below). These mortises are offset because they’re routed before the profiles are sawn.
Saw steps in the front leg blanks so you can rout the seat rail and stretcher mortises. Make stopped tablesaw cuts (on the outside edge of the pattern line) from the bottom of the blank to the start of the curve at the top. Bandsaw the remaining curved profile. Attach support and stop blocks and rout the mortises.
Rough-saw the outside curve at the top of the legs. Then mount the template (on the right side of the blanks) and rout the front leg profiles.
Mortise the Seat Rail, Stretcher and Arm Blanks
The seat rails, side and center stretchers (L) are all the same thickness, so they can all be routed with the same set of cleats mounted on the end-mortising jig (Fig. C, Detail 1, below).
First, rout 1-1/4-in.-deep mortises in the seat rail blanks (Fig. G), centered between the faces and offset from the top edge. Be sure to rout both ends from the same face.
Reposition the right-hand cleat and rout 1-1/2-in.-deep mortises in the stretcher blanks (Fig. H, below).
Mortise one end of both arm blanks (Fig. F). This job requires its own set of extra-wide cleats and support blocks (Fig. C, below).
Make the Loose Tenons
Individual 1/2-in.-thick tenons (Q through X) are cut from long pre-milled blanks. First, plane 2-ft. lengths of straight-grained stock to 1/2-in. thickness and rip them to width. Then shape the edges on your router table (Photo 9).
Your tenon stock should slip in and out of the mortises without binding (too tight) or rattling (too loose). Cut the tenons about 1/16-in. short and test-fit the seat rail and stretcher joints. Adjust the fit by shaving the tenons or wedging the mortises until the adjoining pieces line up with the layout lines.
Fit the Angled Joints
First, find the cutting angle for the stretchers (see Real-World Angles Don’t Lie). Then transfer this angle to your tablesaw’s miter gauge using a sliding bevel square. Mark the stretcher for the angled cut (Photo 10) and cut it to length.
Find the cutting angle for the back end of the arm. Tilt the blade to this angle. Reset your miter gauge to 90 degrees and cut the back end of the arm blank.
Rout mortises in the side stretchers for the center stretcher (Fig. H). Then assemble the sides and install the arm blanks so you can locate and rout the front mortises (Photos 11 and 12).
Assemble the Sides
Mount the arm blanks with tenons installed in both mortises. Trace the arm’s profile onto the blanks while holding the template (Fig. F) against the back leg, flush on both sides. Remove the arm blanks and rough-saw them. Then attach the template and rout the profile on the router table using the flush-trim bit.
Rough-saw and rout both seat rail blanks using the template (Fig. G). Chamfer all the exposed sharp edges on the arms, legs, seat rails and stretchers. The chamfers stop above and below the arm joint on the back legs. Chamfer only the bottom edges of the seat rails. Don’t chamfer the ends of pieces that butt at joints. Then glue each side assembly together (Photo 13).
Assemble the Back
Rout 1-in.-deep mortises in the ends of the crest rail blank (F) and lower back rail (G), using the jig (Fig. C, Detail 1). These mortises are offset (Fig. J and Fig. K, below). Mortise the ends of the front rail (H) now as well.
The 3/4-in.-thick back slats (J and K) require thinner mortises and tenons (Y and Z), but the plunge routing procedure remains the same. Draw layout lines on the rails (Fig. J), clamp on a fence and stop blocks, set the edge guide and always rout from the same face.
Make sure the back slats are the right length. Dry-clamp the crest and lower back rails in place between the glued-up sides and verify the distance between them. Then mortise the ends of the slats using the jig (Fig. C, Detail 3, below).
Bandsaw the curved profile on the ends of the crest rail and smooth it on your drill press with the sanding drum. Next, chamfer all the edges (but not the ends) of the rails and slats.
Make tenon stock to fit the 3/8-in.-thick mortises, using the 1/4-in. round-over bit, lowered slightly, to round the ends. For this 28-mortise glue-up, give yourself some wiggle room by making the tenons slightly undersize (see Oops!, below). Then rely on your layout lines to position the slats when you glue the back assembly together (Photo 14). After clamping, measure the diagonals and make any necessary adjustments to make sure this assembly is square.
Glue the Frame Together
Dry-fit the chair frame and clamp it together. Then determine the exact length of the center stretcher by measuring between the side stretchers. Cut it to fit.
Disassemble the chair and draw the shallow arch on the bottom of the front rail. Flex a yardstick or thin piece of scrap to use as a pattern. Bandsaw the arch and smooth it with the sanding drum.
Glue the chair frame together on a level surface (Photo 15). Use your layout lines to make sure all the rails are in position. After clamping, measure the inside diagonals of the seat opening to check for square.
Install the Seat
Make the seat subrails (M) and the seat slats (N and P). Screw the subrails to the seat rails. Glue and screw the front slat to the front rail, flush with the back edges of the legs. Then install the rest of the slats (Photo 16).
White oak is rot resistant, but left unprotected, your chair will turn gray and may feel somewhat rough, because exposure to moisture will raise the grain. If it stays damp for extended periods, mildew can be a problem. You can get rid of mildew and restore the oak’s natural color by treating it with a deck renewal product. Light sanding will smooth the surface.
We chose an outdoor oil finish (see Sources, below) because it makes the oak come alive with color. It also offers a layer of protection against the elements, including mildew. You should plan to apply (brush on/wipe off) several coats of this finish every year.
The most durable exterior finish is spar varnish, which also gives the oak a pretty color. It’s a brushed-on, high-gloss finish that will last for several years without peeling or cracking. You’ll have to sand it down before recoating.