Plan C A Roubo Bench

The common workbench of André Roubo's time was a single massive plank sprouting four legs. I say "sprouting" rather than "supported by" because this form of bench uses "stool" rather than frame construction—more like a Windsor chair than a table. The version I describe here, fitted with a toolbox with a locking lid set between the stretchers, is based on one I saw in the town of Isle sur la Sorgue in southern France. Simple as it is, this is a challenging bench to make. The timbers are big—hard to find and hard to work. The joints are big too, yet require precise fitting. Done right, though, it's a workbench beyond compare.

When trees were big, so were benches. Old benches, with tops six inches thick and two feet wide, could stand stable on perpendicular legs. As available timbers for the top narrowed, however, perpendicular legs would make the bench too tipsy. But, just like a Windsor chair, narrower-topped benches can regain their stability by splaying out their back legs. These splayed back legs solve one problem but present another. The back legs intersect the top at an angle, with their tenons fitting into mortises angled through the top. The front legs, however, are perpendicular. Having the front and back legs come in at different angles poses no assembly problem when they are independent pieces, but here they are joined by the broad stretchers. In a Windsor chair you can assemble the converging pieces—legs, top, and stretchers like a car wreck played backward, driving each joint tighter as you go. You can build this bench that way, but I propose you try a more amusing solution, letting the court jester of joints rescue the old king of benches.

Wooden Bench Screw

If you look at the dovetails connecting the front legs of the bench to the top, you'll see that they slope in two directions, both up and down and in and out. This means that the legs can never pull down; nor can they pull out to the front. The advantage of this style of dovetail is that it can never come apart. The disadvantage is also apparent—it can never go together.

Or so it seems. This is the rising dovetail joint. It's usually found only in puzzles, fooling us by hiding its slope while letting us continue to think at right angles. The rising dovetail is just a normal dovetail tenon (or pin) tilting toward us. The tenon is at an angle to the length of the leg and to the edge of the bench top. This exposes an oblique slice that appears wider at the end and makes the rising dovetail look impossible to assemble. In our case, however, the rising dovetail makes the bench easy to assemble, because it goes together at the same angle as the sloping back legs. The rising dovetails make it possible to join the bottom frame entirely and then drop the top on with a backward sliding motion.

Start with the top of the top. You want the hardest, thickest, widest piece of wood you can get, but you use what you have. I usually work with oak, but for this bench I lucked onto a plank of hard maple, three inches thick, ten inches wide, and ten feet long. I decided that two, five-foot-long benches would be more useful to me than one longer one. I'm glad I chose as I did, because the five-foot version is almost too much for me to move. The two front legs and front stretcher are also hard maple. The back legs and stretchers are soft maple, which saved money and made the work a little easier.

A flat workbench top is the foundation of everything that you make upon it. In this case, the flat bench top is also the starting point for everything made below it. You level the top, true the front edge, and build on from there. Leveling a great, wide piece of rough-cut hard maple is no joke. You may need a good bit of adze work before using the planes as I describe in Chapter 7. Roubo recommends that you orient the grain of the bench with the heart side up. This ensures that further seasoning will cause the top to crown rather than hollow. Once you establish the flat plane of the top and the perpendicular front edge, you build downward from there to the floor.

The rising dovetail is the second challenge. Our brains struggle to describe three-dimensional work arranged at right angles, and fail utterly when it comes to describing these angled intersections. Even after you've cut one of these joints, you're still not quite sure what you've done. If you have not cut one before, practice on cheaper stock, following the steps illustrated. The dimensions given in the drawing create a slope equal to that of the back leg, making assembly easier.

The back legs have straight tenons with beveled shoulders. They fit into angled mortises, bored and chiseled through the bench top. In this case, the angle of the mortise is easy to find. The top is 10 inches wide, and the desired spread at the feet is 18 inches, so this puts the back legs 8 inches out of plumb. Since the total height from floor to bench top is 32 inches, the splay of the back legs is 8 in 32, or, 1 in 4. Set your bevel to this angle and use it to draw the passage of the mortise on the end grain of the top. Bring these lines across the face and figure 2-----

Splayed Roubo

figure 1. View looking down at the bench top. A glance at the dimensions of the dovetail socket tells you that the slope is one in two—very bold.

figure 2. Still looking down at the bench top. The dotted line shows the dovetail opening on the underside. This opening has the same width and slope as the upper one, but it sits deeper (i 3/4 inches) into the bench top.

figure 3. View of the face edge of the bench top. Connect the top and bottom dovetail socket openings with straight lines. Saw and chisel out the waste.

figure 4. The dovetail tenon in face view.

figure 5. The path of the tenon as it slides up into the socket to fill it. Making the lower dovetail opening 3/4 inch deeper than the top creates a 1:4 angle that matches the angle of the back legs.

The back slope of the dovetail is 3/4 inch in 3 inches, a ratio of 1:4. The back legs splay 8 inches out of plumb in 32 inches, also a ratio of 1:4.

figure 5


figure 1

Splayed Roubo

underside to locate the actual mortise. Using the same 1:4 setting on your bevel, use it to guide your auger as you bore down from the top face of the bench.

In spite of all your care in truing the stock and fitting, the front legs may need a slight push or pull to bring them dead perpendicular to the top. The back legs give you something to push or pull against. Fit all the legs as accurately as you can, drive them into place, and bring the front legs square by either pulling together or spreading apart the feet of each pair. With the legs thus wedged or clamped, hold the stock for the stretchers against them and mark them to fit. French workbenches typically have a shelf for tools set in between, or on top of, the stretchers. The stretchers on this bench are wide enough to fit a floor into grooves plowed around their lower edges. Add a lid, and you have a tool chest. A drawer under the top is also handy, and the one in the Roubo illustration is fitted with a lock as well.

Once the legs and stretchers are joined, stand the base upright, set the top on, and start the tenons into the mortises. Rather than pound on the top to drive the joints home, lift and drop alternate ends of the bench on a stout floor, letting the mass of the top drive itself down. The top will move three inches down and 3/4 inch back as the dovetail tenon rises to fill its space.

The solid, level floor required for this mode of assembly also serves when leveling the bench. Shim up the legs to bring the top level, and use a plumb bob and string to check the front legs as well. You can level the top with more planing, but you can't as readily correct the plumb of the front legs. When it looks level, find the leg with the widest gap between it and the floor, set your dividers to this gap, and scribe it around all four legs. Move the bench to a different spot on the floor and repeat the leveling and scribing before you trim the feet to the scribed lines — the floor may not be as level as it looks.

Now that you're up on your legs with that nice workbench top, it seems a shame to lose any part of it. Still, the bench top has to sacrifice a bit of length to create the tongues to support the frame of the tool well. Use a fillister plane followed by a rabbet plane to take down the ends of the top, leaving a 3/8-inch-square tongue to fit into the matching groove plowed into the skirt boards. This groove in the skirt boards continues all the way around the inner face of all three pieces to support the bottom of the tool well. The back edge of the bench top also gets a groove at the same level to support its side of the tool well bottom.

The flat, heavy top is the foundation, but you still need something to hold the wood against it. You can always sit on the wood for mortising, but for planing and sawing, you need a bench stop, a vise, and some holes for the holdfast. Bore and chisel the mortise for the bench stop — the square sectioned block that you tap up and down to catch the ends of boards as you plane them. Get the holdfast in your hands and try its fit in a test hole before you bore any holes in the bench. Augers are graduated in 1/16-inch increments, and making the hole that much too big means forging another, larger holdfast. This form of bench is best suited to take a front leg vise. A two-by-five-inch leg is fine for an iron screw, but not quite stout enough to take a large wooden screw, so bœuf it up as you see fit.

Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

Get My Free Ebook

Post a comment