TP® BACK PANEL of a lot of case goods is an afterthought, quickly screwed into place before pushing the carcase against a wall where the back is never seen again. But for freestanding pieces or glass-front display cabinets, the back can become the center ofattention. When a cabinet back has to play an upfront role, there are a variety of traditional techniques for installing backs that work well. I'll discuss how these techniques have been adapted to contemporary pieces and present an overview of my method of installing a frame-and-panel back.
On display or hidden away, a back serves some important functions. It adds strength and racking resistance, which is most important for open cases and those with adjustable shelves. On closed carcases, the back keeps the contents in and dust, dirt and foreign objects out. When the back is exposed, it should be visually appealing. And, finally, a back thai is square, will automatically square die carcase when it's installed.
Traditionally, narrow cabinets often had single board backs. Most often, they were set into rabbets in the sides and lop, as shown in Figure 1. Naded into place, the back provided strength and racking resistance while still
BY CHRISTIAN I! I CKSVUOR 1
A RAISED PANEL CAPTURED In grooves in the carcase effectively seals the cabinet against dust and light. Although attractive, this type of back doesn't strengthen the carcase as much as a frame glued into a rabbet. . .
Fig. 1: Back Installation
Carcase backs are usually installed in a rabbet after carcase assembly (left), but they can also be Installed in a groove in the carcase during assembly (right).
Fig. 2: Back Panels from Individual Boards
Tongue and groove
A variety of interlocking joints can be used when making up a back panel from individual boards.
Fig. 2: Back Panels from Individual Boards
Tongue and groove
Back can take a variety of forms to suit the cabi- — net style.
Quartersawn frame stock h.
Flat panel (solid or ply) panel
Flat/flush panel allowing the wood to move. Rarely, single board backs were set into grooves in the carcase before assembly. A variation of this type ofback, that includes two boards separated by a center stile, is shown in the photo on p. 91. Done properly, this method provided a dust-proof, virtually air-tight closure that was also visually attractive. But because space must be left between the carcase and the board to allow for expansion and contraction, this method doesn't provide as much racking resistance for the case.
On wider cabinets, individual boards were joined in a variety of ways, such as shiplap, tongue-and-groove or spline joints (see Figure 2).The shiplap is easy to make but has a major drawback: If adjacent boards bow in opposite directions, the joint opens, allowing in dust, dirt arid light. Nailing shiplapped boards to a fixed center shelf can overcome this problem, as shown in the photo on the facing page.The tongue-and-groove joint solves the problem ofwarping boards by interlocking the tongue ofone board to the groove ofits adjacent board. A minor drawback to both the tongue and groove and the shiplap is that they consume %in. to A in. of the board's width for the overlap.When making a 4-fL- or 5-ft.-wide walnut back, this loss to the overlap can prove costly. The spline joint, which is easier to cut than either the shiplap or the tongue and groove, eliminates the waste by butt-joining boards with thin strips that can be ripped from waste.
Whichever method is used, the boards must be allowed to move. They cannot be glued into place but, instead, must be nailed into the rabbet. However, individually nailed boards don't offer much racking resistance and shouldn't be used on large, empty cabinets, especially those without integral face frames.
Plywood is flat, thin, attractive, has negligible movement and comes in 4x8 sheets. Because it doesn't move, plywood can be glued into
Pinned mortise and tenon
Back panel can Tongues be individual boards, plywood, or solid panel.
A mortised-and-tenoned back frame adds strength and racking resistance to backs made up of individual boards or solid panels and accommodates wood movement.
Pinned mortise and tenon rabbets to provide the ultimate in racking resistance. Yet plywood, too, has minor drawbacks. Unless grain direction is irrelevant, it can't be used on pieces wider than 4 ft., and it comes only in a limited variety ofspecies. Also, plywood's thin veneer faces make it difficult to repair nicks, dents and scratches.
This brings me to my favorite back, the frame and panel, shown in the photo on p. 94. Built just like a door with stiles, rails and panels, it has all the qualities 1 require for a back: strength and racking resistance, air and dust-tightness, solid-wood construction of the same species as the rest of the cabinet and a pleasing appearance that enhances the overall look of the cabinet. Small cases usually get a single panel frame.Tall cases can have two or three stacked panels. Low, wide pieces may require several side-by-srde panels. And large pieces like wardrobes may have stacked and side-by-side panels (see the photo on p. 94).
A frame and panel back can include some features ofother back styles. For instance, individual boards can be set into a mortised-and-tenoned frame (see the photo at right).This maintains the look ofthe traditional, individual-board back while adding to its strength. Another alternative is to use A-m.-thick plywood for the panels. Because the plywood is recessed into the frame, the panel is protected from most nicks and scratches.
But 1 prefer to use solid-wood panels in frames. This gives me the most flexibility regarding the species ofwood used as well as the style ofthe panel. Like doors, backs can have a variety ofpanel styles to suit the style ofthe cabinet, as shown in Figure 4.
Although my first choice is usually a flush panel, I've used several different panel styles. Other options include X-in.-thick, solid flat panels, a variety of raised-panel styles or combination panels with a flat face on the interior and a raised panel face on the exterior. Non-wood materials, such as stained or translucent glass, melamine, slate or composition panels covered with leather or velvet, also can be used for panels.
1 like to use %-in.-thick stock for the frames in all but the smallest cases.This thickness represents a good compromise between strength and weight. Frames A in. thick add too much weight, especially on large cases, and \l-in.-thick frames yield weak mortise-and-tenon joints. I use narrow, quartersawn stock for the frame members to
SHIPLAPPING Framing shiplapped boards is stronger than nailing the boards directly into the back rabbet. Nailing through the boards into a fixed shelf further strengthens the beautiful back on this cabinet built by Ron Layport of Pittsburgh, Pa.
A FRAME-AND-PANEL back with flush panels is built like a door with stiles, rails and panels and is glued into a rabbet in the carcase. It provides racking resistance and keeps dust and air out.
reduce wood movement. Quartersawn stock moves roughly halfas much as plain-sawn stock. By keeping the frame members VA in. to VA in. wide, the overall movement is limited to under %\ in. (for quartersawn cherry) no matter how wide the back. This amount ofmovement is easdy handled by the compression of the wood fibers and wd] not push apart the carcase or break the rabbet joint.
Ifthe bottom rail of the frame is not captured in a rabbet, as shown in the photo above, like all other secondary stiles and rails, can be made as wide as desired. A wider bottom rail allows larger mortise-and-tenon joints and makes a stronger back frame. The mortises and tenons are glued and pinned, but the panels are free to float in the frame grooves. A loose wood panel can be anchored to prevent it from rattling in the groove. Center the panel in its frame, and then drive a 20-gauge brad through the frame and the panel tongue, centered at both the top and bottom of the panel.
Installing; the Back Panel
Before installing the assembled back frame and panel into its rabbet in the completed carcase, 1 trim the panel assembly square to fit snugly into the rabbet, using the lablesaw, jointer and a block plane.The carcase rabbet should be An in. deeper than the thickness of the back. To make it easier to slide the back frame into the rabbet, 1 chamfer the edge along the inside face of the frame with the block plane. 1 also mark the locations of all the carcase's fixed dividers and shelves and the bottom, so I can nail through the back frame into these components to further strengthen the carcase. .1 ust prior to installation, 1 sand the back panel to 32(J-grit on the inside face and ease all the sharp edges.
finally, 1 glue the back into place, spreading glue thinly on both faces of the rabbet as well as the edge of the back. After forcing the back into the rabbet, 1 clamp top to bottom first and then side to side.There should be no gaps between the back frame and the rabbet. Because the back has been squared, it will automatically correct a minor oul-of-square carcase as the back is clamped into place. When the glue is dry, 1 remove the clamps, drill holes at the previously marked dividers, shelves and bottom and nail the back with 4d finishing nails. I countersink the nads about A in. and then plug the hole with small, X-in.-sq. pegs of the same species wood as the carcase, 1 trim the end-grain plugs flush, plane the carcase flush to the back, sand the entire back to 320-grit and, again, ease all frame and panel edges.
CHRISTIAN BECKSVOORT is a contributing editor to Fine Woodworking magazine.
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