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Build progress for cabinet with walnut burl doors

Step 1 - Create the cabinet piece parts - plates, legs, rails or lower stretchers, top plate

Resaw jatoba wood into pieces for the top plate, the sides and the shelves. Bookmatch the sides.

resaw, bookmatch and glueup sheet parts

Glue-up of shelves

Step 2 - Create cabinet top

The cabinet top follows classic Chinese construction techniques. The cabinet top is composed of 4 outer frame members of approximately 2 inches width and 1 1/2 inch thickness, with mitered corner joints and joined together with square tenons integral to the front and rear long members that run through in mortices in the side frame members. For construction purposes make these square tenons extra long with a hole so that special clamps will grab the tenon and tighten the side member to form a tight joint.  Inside the four frame members will be a floating thin panel that is braced across the center with an internal rib. This allows the thin panel to expand and contract as a result of changes in humidity and temperature, yet support any vase or lamp likely to be placed on the cabinet.

cabinet top exploded view

Cabinet top exploded view

cabinet top underside exploded view

Cabinet top underside exploded view. Center rib stiffens floating panel.

cabinet top under view bolted together

Cabinet top under view bolted together with clamps pulling on tenons.
Note the three holes in each corner for the tenons coming up from the legs.
The slots on either side are for the side panels.

cabinet top bolted together

Cabinet top bolted together.
It is important that the floating panel have clearance front and back to expand and contract.

glueing up cabinet

After champhering the edges, glue-up the top panel. Only the mitered joints are glued - the top floats.

Step 3 - Shape the legs and lower rails

The legs in classic Chinese round-corner cabinets have some variation of a rounded exterior profile with an interior square corner and sides.   See below for cross-sections of classic round-corner cabinets.

classical leg cross sections

Classical round corner cabinet leg cross-section and variations.

For this cabinet I am going to use a more hard-edged leg cross-section, using 5 sides for the exterior while still providing the internal square corner and sides.

leg cross section

Cabinet leg cross section, drawing and partially shaped.
The outer champfer is partially cut and will be final-cut just before assembly.
The drawing also shows the geometry of the knife hinge needed for the doors to swing clear of drawers.

To mirror the facets of the legs, the rails or cross-members at the base of the cabinet will also have a multi-sided profile. The rail is actually a built-up piece combining the outer rail and the inner side track for the lower shelf.

rail cross section

rail cross section, composed of two joined members
The outer rail is champhered and drilled for loose tenon.
The inner rail has a slot for the shelf.

Step 4 - Create frame of cabinet from top piece, legs and lower rails

In most round-corner cabinets the legs angle inwards to the top. This gives a pleasing sense of purpose as if the legs are directing the weight of the cabinet to the ground. In this particular cabinet, the angle will be about 1 inch inward over 42 inches, or just a little over 1 degree of tilt. Thus most joints need to be cut for this slight angle. To set the shape of the angled cabinet, make top and bottom temporary jigs.

larger of two hall table tops

Legs held top and bottom in jigs. Cut mortise and tenon joints for lower rails.

joint detail 1

Joint detail 1

joint detail 2

Joint detail 2. The dowel will be replaced by a special square loose tenon.

The top will be attached to the legs with loose tenons (actually dowels). First mortise holes are drilled in the top. then using dowel centers, the hole pattern is transferred to the top of each leg. The mortise holes for these tenons must be drilled at a slight angle in two dimensions. I make a router jig that sits atop all 4 leg tops, and allows me to plunge cut the hole with a sraight router bit.

plunge-cutting mortices for top tenons

Plunge-cutting mortise holes for top tenons

Step 4 - Cut and insert sides and back sheet

Once the cabinet frame has been established, add the sides. To allow for wood movement, the side panels float in grooves in the frame members. The edges of the side panels are all tapered so that they just enter the groove. This helps keep the panel centered in the grooves.  This is classic frame and panel construction.

View of side panel inserted in grooves in legs, rails, and top

View of side panel inserted in grooves in legs, rails, and top
You can see the book-matching in the side panel

another view of side panel inserted in grooves in legs and rails

View from inside cabinet of side panel inserted in grooves in legs, rails, and top

Step 5 - Make and insert bottom shelf, a single lower shelf and two upper drawers

Classic Chinese round-corner cabinets have a bottom shelf, a middle shelf and two small drawers in the upper part of the cabinet interior.

interior showing bottom and lower sheves.

Partial interior showing bottom and lower shelves.
Each shelf has a hidden stiffening rib under its center.
These shelves need to expand and contract so they are held in place with sliding slots all around.

Interior showing drawers and shelf

Interior showing drawer front plate plus middle shelf.

Side view of drawer

Side view of drawer.
Each drawer is assembled with hand-cut dovetail joints in the front.

Interior showing drawers

Interior showing drawers inserted. Handles are temporary.

Step 6 - Experiment to figure out what kind of hinges will work

In most round-corner cabinets the doors pivot on wooden pegs that are integral to the door's outer frame member. While I've made cabinets with this ancient design, I figured to use modern metal hinges for this updated version. The problem is to figure out which style of metal hinge will swing the doors outwards wide enough to enable the drawers to clear. Butt hinges are out - because of the geometry of the door frame and leg, the door would not even open 90 degrees. My first try is with variations of knife hinges. To test their operation without drilling holes in the actual leg, I build a false leg and door that are attached to the real one.

test door frame and leg

Test outer door frame and leg

knife hinge detail 1

Knife hinge with door open -and providing clearance for drawers

knife hinge detail 2

Knife hinge with door closed

The knife hinge idea will look attractive but has two problems. First the hinges on the door side would be VERY difficult to attach. There is no clearance to insert screws into the door leaves.  And second, the geometry of the door swing demands that they be custom-made. So I try a fancy new-style multi-part cabinet hinge with 165 degree opening

test door with fancy hinge1

Test door using modern multi-part 165 degree opening hinge

test door with fancy hinge2

Looking down on modern multi-part 165 degree opening hinge

test door with fancy hinge closed

Test door with modern hinge and door closed

test door with fancy hinge open

Test door with modern hinge and door open

Well, the modern multi-part hinges work - they swing the door out of the way so that the drawers can be pulled out. But in the end they look too big and clunky for the cabinet.

So I'm back to the custom knife hinges design. However, to overcome the two difficulties mentioned earlier - no clearance to insert screws in the door leaf, and non-standard size - the hinges for this cabinet will need to be custom-made to the design below.

Step 7 - Fit and complete the doors

Recall that the walnut burl door panels have a diamond hole in the pattern in their middle. I experimented with a number of overall designs to actively incorporate this as a feature in the doors. For example, to frame the diamond-shape opening in the doors and fill with a plate showing a jewel or sculpture attached to the central locking bar. But in the end all the designs looked clunky and mis-shapen. And so I carefully filled the diamond opening with extra burl. Now the doors will have a more traditional look.

The door frames (stiles and rails) are shaped with a combination of table saw dado cuts and router bits. They are then cut to fit, while allowing a gap of approximately 7/8 inch for the central locking bar. The top and bottom horizontal members will be tenoned into the vertical members. Cut and fit these tenons carefully, always testing the fit of the doors in the opening. Once glued up the doors must fit the opening - there will be little "meat" for further cutting to fit.

This is all a bit complicated by the fact that both the bottom front frame bar and top are still not glued to the casement. They need to be removable until I can determine exactly where the hinge points need to be, and secure hinge pins top and bottom. So in the pictures the bottom frame rail under the door is carefully blocked up to its correct placing when eventually glued.

fitting doors to frame front view

Fitting doors to frame front view
Doors are clamped at this point, not glued yet

fitting doors to frame side view

Fitting doors to frame side view

Chinese elm
Chinese elm