Outdoors projects projects

A seat in the sun

Jim Robinson  |  Feb 6, 2009


old bench
Almost fifty years ago, I constructed a garden seat based on a design in The Woodworker by Charles Haywood. It was made in Japanese oak and has given good service over the years, but it’s now sadly beyond any further patching up, as the photograph below left shows. This seat which forms the subject of this project is a replacement made with European oak. It’s 4ft 3in wide and stands almost 3ft high at the back (see fig 1).
Stock sizes I’ve been using some fairly thick sections of timber recently to construct a bed and a large table, so I was able to use timber left over from these projects for this seat. The legs and arms were made from 3in thick sawn timber, and the seat supports and lower stretchers were taken from 2½in sawn stock. The long rails were from 1½in thick sawn timber and the seat and back slats were from 1in sawn stock.
cutting list
Preparing the seat ends The components that make up the seat ends are all shown on a 1in square grid in fi g 2 overleaf. If you have access to a commercial photocopier or computer, you can enlarge these up to full size (by 200 per cent) to use as patterns. Cut all the patterns out, leaving an extra ¼in around the outline. Use them to make the most economical use of the timber available, photo 1. Then remove the sapwood on the bandsaw, photo 2.

When you are satisfi ed with your positioning, draw around the patterns. Then plane and thickness the timber to 2¾in for the legs and arms, and to 1½in for the centre and side seat supports. Fix your paper patterns to the planed timber using drafting tape; then transfer the outline to the timber using carbon paper, photo 3.

Use a bandsaw to cut out all the blanks, photo 4, sawing a fraction outside the line. Make sure you leave suffi cient at the ends for the tenons. Use a planer to smooth the fl at parts of the legs, photo 5, and a combination of spokeshave, belt sander, plane and scraper to smooth the rest.

paper patterns         cutting with a bandsaw         marking out
Photo 1. Use paper patterns to position the components for the most economical use of the timber
Photo 2. Remove the sapwood with a bandsaw before planing and thicknessing the wood
Photo 3. Transfer the outlines of the components to the planed timber using a pencil and carbon paper
Assembling the seat ends When you have all the parts ready, position the front and rear legs the correct distance apart and then place the arms, side seat rails and stretchers on top of them in their correct positions, photo 6.

It is now a simple matter to draw a line at each side of the cross pieces so that the mortise positions can be determined, also the angle of the mortises relevant to the face. Use a pencil point resting against the legs to draw the shape and position of the shoulders, ready for when you cut the tenons.

Note that the stretchers are positioned in the centre of the leg thickness, but the side seat rails are positioned so the side facing the seat centre is fl ush with the inner face of the legs. This makes it easier to fix the side seat supports on the inside of the rails.

Figure 1
Cutting the mortises I removed most of the waste from the mortises with a router guided by a fence, photo 7. If you use this method, you’ll need to clamp a straight edge to the side of the curved section to provide a bearing surface for the router fence. Similarly, clamp a straightedge to the side of the back legs to guide the router, photo 8, so the mortise is sunk at the correct angle.

To complete the mortises, trim their ends square by hand. Of course, if you have a mortising machine you can cut all your mortises in one operation.

cutting profiles with a bandsaw
Photo 4. Cut the parts to the
outline on the bandsaw, cutting
just outside the marked lines

planing timber flat
Photo 5. Plane the fl at parts
as far as possible on a planer

laying out
Photo 6. Place the cross pieces on top
of the legs and mark their positions.
Also mark the shoulders on the
underside of the cross pieces

using a router
Photo 7. Use a router to remove most
of the waste from the mortises,
ready for trimming by hand

routing the back legs
Photo 8. On the back legs you’ll
also need to provide a straight
edge for the router to bear against
Cutting the tenons Form the tenons on the ends of the stretchers and the side seat rails. I cut all the shoulders by hand, but cut the tenons to thickness using the bandsaw guided by a fence. Some of the shoulders are curved slightly, so I shaped these with a paring chisel.
Gluing up: the first stage Glue each pair of legs together with a stretcher and a side seat rail, but leave fi tting the arms until later. Hold each assembly squarely and securely in cramps until it’s set hard, photo 9.

I used Cascamite glue because the seat has to endure outdoor conditions. I’ve tried polyurethane glue in the past, but I prefer Cascamite because I find it less messy. Use plenty of glue in each joint so that there are no capillary paths to allow rainwater to penetrate. This does involve more cleaning away of surplus glue, but unlike a piece of indoor furniture any remains will not become obvious with staining and polishing.

Adding the arms When the cramps have been removed, lay the arms across the legs and mark the shoulder at the top of the front leg and at the end of the arm where it joins the back leg, photo 10.

The arms have to fi t into the mortises on the rear legs, so you need to form a slight chamfer at the end of the tenon to enable the arm to fi t over the tenon at the top of the front leg. The arm will be quite secure, especially when the joints are pegged. Glue and cramp the arms in place, photo 11, againchecking that everything is square, and set the assemblies aside to dry.

The front and rear rails Cut the front and rear seat rails to length and form the tenons to fit the mortises already made in the legs. Shape the underside of the front seat rail as shown in fig 3. Mark out the shape of the top back rail using the squared drawing in fig 3 as a guide. Cut both rails on the bandsaw, and smooth the sawn edges. Then form the tenons on their ends.

Drill and counterbore four holes up through the underside of each seat rail (shown in photo 15). The counterbores should be deep enough to accept 2in No 8 brass screws, so that they will have about ½in of thread projecting to enter the undersides of the front and rear seat slats.

glueing up laying out clamping up
Photo 9. For each end frame, glue the legs, stretcher and seat rail together and clamp them securely
Photo 10. Lay each arm across each end frame and mark the shoulders with a marking knife
Photo 11. Cut the mortise and tenon on each arm, fit it to its end frame and glue and clamp it in place
cutting mortises glueing up bench in clamps
Photo 12. Sink the mortises in the back rails with a router and then trim them square by hand
Photo 13. Assemble the back panel and clamp it before trimming the rails to length and cutting the tenons
Photo 14. Cut notches in the front and rear seat rails for the centre seat support (inset), then assemble and cramp up the main carcase
figure 2
The back panel Before joining the seat ends together with the front and rear rails, you need to assemble the back panel. This model is a two-seater, so there are fourteen evenly spaced slats in the back panel. If you want to build a three-seater, simply extend the rails and add more slats.

The rear slats are 1¾in wide and ¾in thick, so make the mortises in the upper and lower back rails to this size, photo 12; space them as shown in fig 3. Because there are no shoulders, fitting the slats is easy, and if one has to be replaced in the future it will be simple to remove. Use a router to cut the mortises to depth, and square the ends to the 1¾in length by hand. Then assemble the back panel and cramp it up securely, photo 13.

Assembling the carcass Before gluing the ends to the rails to form the basic carcass, photo 14, take out a notch in the centre of the inside of both front and rear seat rails (inset) to receive the centre seat support. It’s much easier to do this at this stage of the assembly, before the rails are glued to the ends.

After removing the cramps, shape the side seat supports to the same profile as the side seat rails, but with a projection on each end (see fi g 4). Shape the centre seat support in the same way, with a projection at each end to fit the notches in the front and rear seat rails.

figure 3
Making the seat slats Cut the seat slats from 1in sawn material, and plane and then thickness them to 7⁄8in (or, if the material allows, to 1in). Before fixing the slats, take off the sharp edges by planing a 45° chamfer on the top edges. Work a 3⁄8in radius on the front edge of the front seat slat using a self-guided router cutter. I also used a 1⁄8in radius self-guided cutter to take the sharp edges off the ends of all the rails before joining everything together.
figure 4
Preparing the seat supports The seat slats are fixed in position by 2in No 8 brass screws driven up from below, through clearance holes drilled and countersunk in the seat supports and through counterbored holes in the front and rear rails.

When you have prepared the seat slats, fi t the centre seat support in place without adhesive, and cramp the side seat supports to the side seat rails. Space the eight seat slats evenly one by one on top of the seat supports and mark the centre of each slat lightly on the sides of the seat supports. Then remove the seat supports and drill the eight clearance holes through each one (shown in photo 15).

Fitting the seat slats Glue and screw the side supports to the side seat rails with four 2in No 8 brass screws. Glue the centre seat support in position and strengthen the joint by inserting a 2in No 8 brass screw through each end at an angle into the rail below, photo 15.

Cramp the seat slats in place, photo 16, using the offcuts from shaping the seat supports to secure them, and drive screws up into them from below through the pre-drilled holes in the seat supports. Add the wider front and rear slats, driving the fixing screws up through the counterbored holes in the front and rear rails.

joining components holding slats in place using a dowel plate
Photo 15. Screw the side and centre seat supports to the bench after drilling clearance holes through them for the slat fi xing screws
Photo 16. Use cramps and the offcuts from the seat rails to hold the slats in place. Then turn the bench upside down and drive in the slat fi xing screws from underneath
Photo 17. Use a dowel plate situated over a convenient hole in the bench to make the oak pegs, then use them to peg all the main joints
Pegging the tenons All the tenons are pegged with ¼in diameter oak dowels. Holes are first drilled to a little over half the thickness of the legs to ensure the hole goes through the tenon and a short way beyond.

I haven’t found a commercial source of ¼in diameter oak dowel, so I made my own using a dowel plate. I fi rst shaped the pegs roughly a little oversize from straightgrained off cuts before driving them through the dowel plate, which was strategically placed over a hole in the bench, photo 17. This results in a clean, accurately-sized dowel.

Glue the dowels and drive them into place, leaving their heads slightly proud of the surface. When the glue has set, cut the dowels off almost fl ush with the surface; I used a special saw for this which is made without any set so it doesn’t mark the background. Then pare them fl ush and sand them smooth.

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