Craft a Curved Wall Cabinet - Canadian Woodworking Magazine

Heirloom Project: With curved sides, and scalloped, coopered panels on all exposed faces, the stunning details of this James Krenov-inspired cabinet can be enjoyed for a lifetime.

Craft a Curved Wall Cabinet

Craft a Curved Wall Cabinet



Photos by Jacques Breau; Illustration by Len Churchill

The shape of this cabinet is symmetrical and makes use of the same curve on the sides and front. Having selected wood for the project, I proceeded to make a full-size, top-view drawing.

INFO:DIFFICULTY – 4/5, LENGTH/TIME – 4/5, COST – 3/5, SPECIAL TECHNIQUES – CURVED PARTS, VENEERING
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Bent laminations
The bending form was cut on the bandsaw from a solid piece of wood and trued up by hand, taking care to not introduce any twist into the form. I kept the off-cut to use as a caul during clamping and as a curved fence for my router table. I laid up the curved rails for the door and sides using five 1/8" plies and epoxy.
 
Once the epoxy was fully cured, I removed the clamps and cleaned up the convex face of the lamination, and ensured that the face was flat and free of twist along its entire surface. I then jointed one edge, and cut the other edge parallel on the table saw. The inside face then gets checked to ensure that it is parallel to the outer face. If the form and laminations are carefully prepared, this should take no time at all.
 
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Curved Joinery – The joinery for the curved door and side rails are made the same way. After the workpiece is cut to length with the help of a curved caul (above), the shoulders are cut while being supported by a wood block (below).
 
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Frame
I added a slightly unorthodox detail to the lower portion of the sides and door frame, in order to create a stronger visual. There are essentially two lower rails for these three sub-assemblies, plus a similar detail for the back panel. In each case, the lowest rail acts as the main structural member, and is joined with bridal joints. The lower-middle rail, about 1/8" above it, is fixed in place with floating tenons.
 
The mortises in the stiles are fairly simple, since the members are straight and square. Depending on your machinery, you could tackle the mortises on the bandsaw, the table saw, the shaper, by hand, with a horizontal boring machine, or with a router. Do the upper and lower bridal joints first, then move on to the floating tenons for the lower-middle rail.
 
The tenons, although on curved members, depart from square joinery only slightly. The shoulders and cheeks are straight and square. We need to properly hold the curved parts for the cuts in order for things to work. We first need to cut all the parts to length with the ends perpendicular to the tangent of the curve. We will use this cut to reference all of the others. Make sure all the matching rails are cut at the same time.
 
Using the end cut as a reference, make two cradles that will hold the curved rail with the end perpendicular to the table, one for the curve facing up, one for the curve facing down. Once you have scribed your shoulder, use these cradles and a tall stop block to make the cuts. Make sure all of the cuts of the same length are done at the same time.
 
Once the shoulders are cut, proceed with cutting the cheeks. Use your favourite method for this, making sure that the cut is perpendicular to your reference end. I used the off-cut of my bending form as a sled and cut the cheeks on the bandsaw. Proceed with fitting your joints, ensuring tight shoulders.
 
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Tenon Cheeks – With the shoulders determined, Breau uses a curved caul and his bandsaw to cut the cheeks of the joints.
 
Top and bottom panels
The top and bottom for this cabinet consist of shop-sawn veneer over birch plywood. I selected my plywood carefully, making sure that the sections I chose were as flat as possible. I used 5/8" plywood for the top and bottom cores, but added a layer of 1/8" thick plywood to either face of the cabinet bottom, to give it a stronger look.
 
Once the cores are cut to size and shape, I glue a piece of wenge to the back edge. By adding a 1/8" thick wenge to that edge of the core, before applying the face veneers, both visible surfaces will have continuous wenge grain extending all the way to the very back edge of the panel.
 
To add a touch of liveliness to the piece, this cabinet is getting a relief detail around the top of the top, and the bottom of the bottom. For this, I’m going to add a 1/4" square strip of wenge into a rabbet in the plywood before gluing the veneers on, so the routed detail will reveal only wenge. Once the veneers are applied, I will relieve the corner with a straight bit that I have modified by rounding the corner to a 1/16" radius. This bit leaves a cut with a nicely rounded inner corner. A small core box bit will work as well.
 
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Decorative Rabbets – Because the underside of the bottom, and the upper edge of the top, will both receive decorative rabbets, Breau machines a small rabbet into the core and glues in a piece of solid wenge. Once the face and back veneers are applied, and the decorative rabbet is cut, nothing but solid wenge will be visible.
 
Sawing veneer
To saw the veneers, I use the bandsaw, jointing the face between each slice. I aim to have the veneers at 3/32". To glue up panels of veneer, I use a hand plane and a shooting board to square the glue surface. With a jointed edge on the veneer I stretch masking tape across both sides of the joint, add a bit of glue and fold the pieces together. I do my best to have all of the jointed faces facing the same direction. Once my sheets are created, and the jointed face has been scraped clean of glue and is reasonably flush, I lay the core over them to trace the shape, then cut them oversized on the bandsaw.
 
I glue the jointed faces down onto the substrate using a clamp and caul press system. A vacuum bag or mechanical press would also do the trick.
 
Once the panels are veneered, I trim the overhanging veneer to the substrate and run them through the thickness planer to clean up the bandsawn face, and bring everything flush. I then apply the edging to the front and sides with high-quality packing tape. The sides get the edging first, in order to have an uninterrupted front face.
 
I like to gang parts and pattern rout them to each other to ensure that they are identical. I do this with the top and bottom after all of the applied edges are glued on. I then set up the router with my modified bit, and relieve the outer corner using the off-cut from my bending form as a curved router fence.
 
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Jointing and Truing – After the veneers are cut, they need to be edge-jointed and glued together with glue and tape. When dry, the inner face of the veneer sheet is scraped smooth so it can be applied to the bottom and top cores.
 
Doweling
Once the main parts for the cabinet are cut to size, it’s time to join them using dowels. To ensure proper alignment between the top/bottom and the sides, I make a one-piece doweling jig from 5/8" plywood. I pattern rout the plywood to the same size and shape as top/bottom. Since the side assembly is going to be inset from the outer edge of the top and bottom I cut a 1/8" deep rabbet along the outside corner of the dowelling jig. I then pattern rout the entire doweling jig to this inner rabbet, making it set back from the top and bottom.
 
To register the jig to the parts, I glue cleats to the back of the jig. These cleats will hook over the back edge of the workpieces. I also make sure to label the jig with “top inside” and “bottom inside”. Be careful to maintain this orientation when drilling for the sides.
 
When laying out my dowels, I typically put one in the center of the joint, one that intersects the rabbet for the back, one as close to the front as I dare, and then I fill in the middle. The rest is easy. Center the jig on the top or bottom and drill your holes on the drill press. Make sure to set your depth stop, or mark your drill bit with tape. It’s an awful feeling to drill through a finish surface. Once the top and bottom holes are drilled, clamp the jig to the sides and drill them with a hand drill. To finish, lightly chamfer the edges of the holes.
 
Don’t dry fit your cabinet with all of the dowels in place. This not only makes it hard to get the cabinet apart, it also loosens the fit of the holes a little. Use only two dowels per joint, in the holes that are second from either end.
 
Now that the cabinet is dry fit, you can proceed with flushing up the back of the cabinet, and marking and routing a rebate for the back panel.
 
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Offset Dowels – Because the side frame assembly finishes 1/8" inside the top and bottom panel, the dowel jig needs to be centred accordingly. Breau offset the edge of the plywood dowel jig 1/8" from the edge when drilling the holes in the top and bottom, and places the jig flush to the edge of the sides when drilling dowel holes in the frames.
 
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Drilling Dowel Holes – With the top and bottom panel aligned with the outer edge of the jig the dowel holes can be made. Notice the solid wood notch on the back of the jig. It references against the back of the top and bottom panels during boring.
 
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Offset Drilling – With the frame aligned with the inner edge of the rabbet in the dowel jig, and clamped in place, dowel holes in the frame can be created. Use tape or a stop to ensure you don’t drill through the frame.
 
Four spruce panels
I wanted to play with the idea of being both convex and concave at the same time. This came to fruition in the door and side panels, as well as with the rounded corner detail in the top and bottom. I left the back panel flat. The main form of the three curved panels are convex, coopered panels, made using basic coopering techniques. From there, I departed from the typical coopered panel. The backs of my staves have remained flat. I did this because I didn’t have enough thickness to curve the inside. The outsides of the staves have been hand planed to a concave shape, and a chamfer has been added to the outside surface at the joint.
 
I then routed a lip along the top, bottom and the sides of the panels with my modified straight bit. To rout an even arc into the curved edge, I used a curved fence of the same radius, and positioned it slightly overlapping the bit. The curved door followed a perfect radius as the rabbet was made.
 
The resulting tenons are going to be set into a rabbet that is milled into the frame. The panels are then held in this rabbet, either with straight pieces on the straight edges, or strips that have been shaped to nestle into all the different facets of the panels on the curved edges. The back panel is constructed like a regular frame and panel, in that the panel is trapped in a frame, but can move with the seasons.
 
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Power First, Then Hand Tools – With the panel assembled Breau used a 45º grooving bit to establish the grooves, then fine-tuned them with a shoulder plane.
 
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A Double-Curve – Breau used a round-bottom plane to create concave surfaces between the grooves.
 
Drawer pocket
The drawer pocket is made up from one horizontal partition, and two vertical partitions. It is important to maintain a square and true pocket to ease drawer fitting.
 
To avoid having to fit the horizontal partition to the curved inside surface of the cabinet, I routed two dadoes in the sides using a router table. I simply laid the assembled side flat on the surface of my router table and routed a stopped dado that was just deep enough to run the entirety of the inner, curved face of the sides. The resulting dado was straight. Now it’s a simple matter of cutting the proper angle onto the partition to match the routed dado.
 
The vertical partitions are held in place with splines that are routed into the bottom of the cabinet and the underside of the partition. The inside surface of the vertical partitions should finish just inside the inner corner of the cabinet’s frame. It will be only slightly visible with the drawer in place.
 
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Faceted Strips – With masking tape applied for visibility, the door and side panels can be placed on top of the strip stock, and the exact shape transferred.
 
Shelves
The shelves are simple veneered panels. The holes for the shelves are drilled using a long stick with a cleat on the end before glue-up. Make sure the orientation is marked to ensure the shelf doesn’t rock.
 
Glue-up
Before gluing up the cabinet, ensure that you have made provisions for any work that would be difficult to do once glued up. This includes cutting the back rebate, the hinge mortises and drilling for the shelf pins. Glue dowels into the sides, let them dry, and cut them to length before proceeding with the final dry run.
 
I pre-finish all of my parts before glue up. This entails doing all of the final surface preparation and applying the finish. I also make sure to wax the dry-fit joints to make squeeze out easy to remove. I then arrange all my cauls and clamps and get one dry run under my belt. Care must be taken to ensure the carcase remains square once the glue is applied. I check the diagonals, and adjust the clamping pressure accordingly.
 
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Assembly – Don’t jump the gun; it’s much easier to apply a nice finish before assembly. Cauls assist with transferring clamping pressure, and protect the finish.
 
Fitting the back panel
Once the cabinet is glued together, I fit the back panel to the opening. I do this by tackling one dimension at a time, usually starting with the long dimension. I remove material incrementally and check often. It’s best to put a slight bevel, towards the inside of the frame, to help achieve a tight fit at the outside of the joint.
 
Hanging the door
The first step in hanging the door is to fit the door tightly to the opening and check for any twist that may be present. Take out as much twist as possible now, before installing the hinges. Do this by removing material where needed, and by moving a corner of the door in or out slightly to compensate for the twist.
 
With the hinges fixed to the cabinet, position the door, mark the location of the hinges on the door and install the door. You will have to remove material from the top and bottom of the door for it to swing freely in the opening and finish with an even gap.
 
Curved drawer
The drawer front follows the same curve as the rails, top and bottom, and is created using the same bent lamination methods. Cutting dovetails in the curved front follows the same principals as cutting dovetails on a 90º joint with a few minor differences.
 
Start by cutting your back piece to length; it will be the length of your drawer opening, plus however much you plan on leaving the dovetails proud of the sides, plus an extra little bit for fitting. With the back cut, use it as a jig to cut the front at the proper length. Do this by laying the front on top of the back and cutting them flush on the table saw with a cross cut sled. This trick only works if the curved front isn’t much longer than the back; otherwise, the curved ends would butt into the base of the cross cut sled. This will give you both the right length, and the correct angle. Transfer this angle to the front of the drawer side while cutting them to length.
 
Make a chopping block that sits in the curve of the drawer front while being parallel with the end of the drawer front. This will ensure that the pin sockets are angled correctly. Sawing and chopping happens just like it would in regular dovetails, while maintaining the proper angle. Before gluing the drawer together, make a groove for the drawer bottom to slide into. The width of the drawer back gets reduced so the bottom can slide in from the back. Use the groove as a reference.
 
The curved drawer front could easily be left in one piece, but I choose to rip it in two for aesthetic reasons. I then fitted a small tab in the kerf to act as a pull.
 
Once the drawer is glued up, fit it to the pocket, being careful not to blow out the end grain. Then, cut and fit the drawer bottom, allowing space for seasonal movement in the drawer front. I fix the bottom to the drawer back with a small screw. I also use the drawer bottom as a stop, by allowing it to protrude the required amount to bring the front of the drawer into position.
 
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Cutting Curved Drawer Parts – With the drawer back cut to size, Breau places the curved front on top of it, and cuts it to length. This technique works well, as long as the curved front isn’t too long and butts into the cross cut sled’s surface.
 
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Angle Dovetails – An angled block clamped in place is all that’s needed to guide you when cutting dovetails in the curved drawer front.
 
French Cleat
To hang this cabinet I made use of a French cleat. A French cleat is made of two similar pieces, both with a 45º cut on one long edge. One part is attached to the wall, with the angled edge at the top pointing down towards the baseboard. The other half is attached to the back of the cabinet, with the angle pointing towards the top front of the cabinet. The two angled edges mate when the parts are brought together, pulling the cabinet towards the wall, creating a secure joint. Hanging cabinets using this method is extremely easy; simply screw the wall half of the cleat to the wall at the desired height, and drop the cabinet on top of it. The downside is that it robs some interior space from the cabinet, since the back panel needs to be set in that much more to accommodate the cleat.

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Coopered Doors (Aug/Sept 2014)
Dowel Joinery (Feb/Mar 2014)


jacques_breau
JACQUES BREAU
jbreau@endgrain.ca
Working out of a basement shop, Jacques is very happy that his newborn son would sleep through a hurricane. He can’t wait to have a new helper in the shop.

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