I selected white oak (Quercus alba) for this project because it is a hard, fairly straight grained wood with outstanding wear resistance and good decay resistance. It machines well, and is easy to stain and finish with no need to fill the pores. Besides, it’s a classic wood with a great pedigree, being the preferred choice for Craftsman style furniture. Other good woods for outdoor furniture include redwood, western red, eastern white cedar or one of the popular exotic species such as ipe, meranti, or teak.

All the tenons on this bench are straight and fairly uncomplicated to cut, except for the tenons on the arms (I), which have angled shoulders, and the double tenon on the center seat support (D), which is angled down. These tenons require careful setup and some handwork, but are certainly within the scope of the woodworker with average woodworking skills. All of the mortises are straight and are router-cut except for the two mortises in the back legs (A) that accept the arms. The easiest way to cut the tenons is on a table saw equipped with a tenoning jig (see Resources, below). The mortises were cut using a plunge router equipped with an adjustable straight edge guide and a ½” spiral cutter. Other methods of cutting mortises abound but this method is ideal for a small shop, requiring very little investment. If you haven’t made a mortise and tenon joint before, or it’s been a while since you last used this joinery option, I suggest you cut a few practice joints before committing to this project.

It’s convenient to mill all the lumber for this project up front. Mill them slightly oversized and then dress them to finished dimensions as you build the project. When you set the pieces aside ensure that you sticker them to allow for adequate air flow. Most of the pieces are 1 ¼” thick, which I milled from 6/4 (1 ½”) stock. I couldn’t find any 8/8 (2″) stock for the legs, so I laminated two pieces of the 6/4 stock together. On the materials list you’ll note that I allowed extra length for the tenons. Except for the back slats (J), the arms (I) and the center rail (D), all the tenons are ⅞”, and the corresponding mortises are 1” deep.

This leaves a bit of space for any excess glue. Finally, it’s critical to ensure that all the boards are milled square and to the exact same thickness.

Shape the Back Legs

The back legs (A) are joined by scarf joints cut on a tapering jig. Start with stock about 38″ long. Measure down 18 ⅝” on the front side of the legs and place a pencil mark. Clamp a leg on the taper jig at 10º to the blade, and cut off the bottom of the leg. Repeat this for the other leg, and then glue the cut off pieces to the opposite sides of the legs to form the bent back legs of the bench. Use a good quality polyurethane glue (elmers.com), epoxy (ecopoxy.com) or high strength wood glue (gorillaglue.com). Don’t skimp on the glue and use plenty of clamps. You’ll also want to ensure that the pieces don’t slip out of alignment as you apply clamping pressure. After the glue is dry, scrape off any exposed glue, and then joint the front and side faces to the final dimensions.

Cut the Mortises

There are 21 mortises to cut on this bench: five on each back leg (A), three on each front leg (B), one on the front rail (G), one on each arm (I) and two in the center bracket (L). Rather than cut individual mortises on the crest rail (H) and back rail (F) to house the back slats (J), I routed a simple groove, and used filler blocks (M) to align the slats.

The mortises for the legs (A, B) and front rail (G) are cut first. Before cutting the mortises ensure that all your stock is milled to final thickness and width. To rout the mortises I used a plunge router equipped with a ½” spiral cutter and an edge guide. Begin by marking out all the mortises, centering them on the stock width. On the legs the mortises are ½” wide by 2″ long and 1″ deep (except the mortises for the arms). Cutting a 1″ deep mortise in hard wood is tough on routers and bits, so cut in multiple passes and then square the ends of the mortises to the line using a ½inch chisel and mallet.

While I used a router to cut the mortises you could also use a mortiser. If you don’t have access to a router, you can also cut the mortises by hand, first drilling out the waste with a 7⁄16″ Forstner bit and then finishing with chisel and mallet.

Cut the Tenons

I cut the tenons using a tenoning jig and sliding table on a table saw. Other options include routing the tenons on a router table, or cutting them by hand with a tenon saw. First, cut the rails (E, F, G, H) and seat and center rails (C, D) to their final length. You will only cut the tenon on the front of the center rail (D) for now. Cut the shoulders first on the table saw. Clamp a stop block ⅞” from the opposite side of the blade, set the blade height to ⅜” and cut all four sides on the rails and seat supports. Set up the tenoning jig to cut the cheeks at ⅜” wide and to ⅞” deep. Careful setup of the tenoning jig is paramount here, so take your time. I always cut a test piece first to ensure that the tenons fit the mortises snugly. It’s also practical to cut the tenons just a smidgen oversize and adjust them during assembly for a perfect fit. Cut the remaining end cheek cuts by hand using a crosscut saw; these cuts are not critical. Note that the tenons on the front rail (G) and the front of the seat rails (C) are mitred where they meet inside the front legs.

Shape the Crest Rail and Seat Supports

Begin with 5″ wide stock for the crest rail (H), cut to finished length. Draw a layout line for the shape of the rail on the bottom edge of the stock, and then cut the shape on the bandsaw. Use the off-cut as a template to lay out the top of the stock. Cut this on the bandsaw also. Then smooth the cut lines with a hand plane, spokeshave, or sander.

On a piece of ¼” MDF draw out the shape for the seat and center rails (C, D). Cut out the shape on the bandsaw and smooth the cut edge. Use this as a template to lay out the cut lines on the seat support stock. Cut the pieces to shape on a bandsaw. Clamp all three pieces together and smooth the shape with a hand plane or sander.

Cut the Groove for the Back Slats

The crest rail and the lower back rail are both grooved to receive the back slats (J). Rout a groove ⅜” wide and ½” deep. I found it easiest to rout the groove with a laminate trimmer equipped with an edge guide because it’s small and square base allows the trimmer to follow the curve of the crest rail easily. The edge guide centers the cut on the stock. Take several passes at increasing depth rather than a single full depth cut.

Fitting Tenons to Mortises

Each tenon must be carefully fit to its mortise to ensure a strong joint. You will find it helpful to label each joint to ensure correct fitting. You may have to trim the tenons very slightly with a chisel until it fits its mortise snugly; hand pressure and a little wiggling is all that is required to assemble the joint. Pare a little off both surfaces of the tenon to maintain centeredness. Check also that the cheek cuts are flush and even, and trim as required.

Cutting and Fitting the Arms

The rear of the arm (I) is mortised into the back leg with an angled tenon and mortised to the top of the front leg with a 1″ square tenon. Rout a ½” mortise in the rear leg starting at 23 ½” from the bottom. The mortise is 1″ long and 1 ½” deep. Square the ends of the mortise with a ½” chisel. Cut the end of the arm stock at a 10º bevel. The cheek cuts will also be cut at this angle. Cut a wedge of plywood about 10″ long to use as an angle gauge. Set the fence to make the face cuts, with the first cut at 2 ½” and the second at 3″. The top shoulder cut is square to the edge of the arm but at a 10º bevel. There is no bottom shoulder cut. Test fit the tenon to the mortise and trim as required.

Cut a 1″ x 1″ mortise on the front bottom side of the arm. I drilled out the waste with a ⅞” Forstner bit and then squared the mortise with chisel and mallet. Cut the matching tenon on the top of the front legs on the table saw with a tenoning jig. The arms can now be shaped to size. Again, make a template out of ¼” MDF to ensure a consistent shape on both arms. Ensure that the sides of the arms are flush with the sides of the rear legs.

Fit the Back Slats

Assemble the entire bench, and carefully check for square and a good fit of all frame components. Now is the time for minor adjustments as required. Disassemble and sand all components to 220 grit. You can now glue the seat rails (C) and lower rails (E) to the front and rear legs (A, B). After the glue has dried remove the clamps and assemble the rest of the bench temporarily without glue. This will enable cutting and fitting the back slats, which vary in length.

With the bench assembled, measure the length of the first two back slats (J) closest to each back leg. They should measure 11 ⅞” plus ⅝” for a 5⁄16″ tenon on each end. Cut the four slats to length. Cut the tenons with a dado cutter in a router table and check the fit. Disassemble the bench and clamp the lower back rail to a large flat work surface, fit the four slats and add the crest rail. Clamp the crest rail to the work surface checking for square. The remaining back slats are all curved at the top and must be marked and cut individually. Starting with the middle slat, measure its location, check for square to the lower rail and scribe a line for the top cut. Cut the curve on a bandsaw, place it back in position, and mark the length at the lower rail, add ⅝” and cut to length. Cut the tenons on both ends and fit. Repeat this for the rest of the slats. Cut filler pieces (M) to length to establish the spacing between the slats on the lower rail. Glue the slats into place in the lower rail adding the filler pieces as you go and keeping the slats square. Add the crest rail, gluing it to all of the slats, and installing the filler pieces. Check for square on all back slats and even spacing at the crest rail, and then clamp the assembly together.

Fit the Seat Slats

The center rail (D) has a double tenon on the end that fits into the center bracket (L). As for the tenons on the arms, these tenons are angled down at 10º, and do not have any shoulders. The matching mortises on the center bracket can be cut by hand or with a router.

Assemble the side assembly to the back assembly with the front rail (G) in place, checking for square. Once the glue has dried, position the center rail (D) in place, gluing and screwing the center bracket (L) to the middle underside of the back rail (F). Cut the seat slats (K) to length. Drill and countersink the seat slats into place, and then cover the screws with plugs. You will need to trim the front one so that it fits between the front legs.

Finishing

Before applying a finish, do a final finish sanding of all surfaces with 220 grit sandpaper. If you did the bulk of your sanding before assembly, this will be a quick job. Check carefully for glue and clamp marks. Spray the bench with water and allow it to dry completely. This will raise the grain for a final sanding with 220 grit. Now is the time to apply an optional stain. Choose a good quality oil-based exterior fence and deck stain (circa1850.com) and apply three coats liberally with a brush, watching for drips as you go. Sand lightly between coats and allow the bench to dry for 48 hours before placing it outside. A well-constructed and carefully finished bench will last a long time. To prolong its life, store it indoors during the winter, particularly in harsh winter climates. You might also consider a cover which will help reduce the impact of UV rays.

After you’ve completed this project you’ll want to place the bench in a nice shady area in the back yard, stoke up the barbeque, and invite your mates over for a bit of well deserved gloating.

RESOURCES

The Well Dressed Board, Feb/Mar ’08 Issue # 52

Tenoning Jig, Apr/May ’07, Issue # 47