Like the chest’s, the cabinet’s carcase is half-lap-dovetailed; combining mahogany on the sides with pine top and bottom. Before assembling the cabinet carcase, trenches were cut into the sides to accommodate the adjustable shelves, and rebates were cut into the rear edges to accommodate the cabinet back.
During the eighteenth-century, cutting shelf supports from the solid was accomplished in one of two subtly different ways: The first method simply involved cutting trenches that encroached into the nominally 3/4″ or 7/8″ thick carcase sides – much the same as cutting dustboard trenches in chest carcases.
‘Worked-up’ shelf supports required much thicker carcase panels for a more robust appearance. A rebate or moulding – the same depth as the proposed trenches – was first formed down the front interior edge of the panel, delineating a solid, unbroken carcase side panel. The worked-up shelf supports were then formed in the ancillary material in the normal way, giving the supports the illusion of being separately applied.
Both these formats of shelf supports are found in ordinary and quality work alike and with this cabinet being relatively narrow (34″ wide internally), I opted for cut-in shelf supports.
The backboards on a chest of drawers (or bureau etc.) normally comprise several pine boards butted together (vertically or horizontally) and nailed onto the back of the carcase. Although rudimentary, these simple unobtrusive backboards serve the purpose adequately. Bookcase and cabinet backboards on the other hand are visible with the cabinet doors open and ordinary butted backboards with the usual gaps and splits would detract from otherwise fine cabinetwork. Before continuing with a solution, there’s another aspect worth considering.
The carcase of a chest of drawers resists racking well; due largely to its dovetailed construction, but also in part, to its many internal structural ribs (the dustboards) and, to a much lesser extent, the drawers, but in truth, there aren’t many shearing forces exerted on the average chest. However, a bookcase or (unfitted) cabinet with loose, book-laden shelves and heavy doors (especially if glazed) – whose mass shifts wildly as they are swung open – has much less to resist racking. Nailed-on, shrunken and/or split soft pine butted backboards offer little resistance to this potential degree of racking. The solution is a frame-and-panel back.
The panelled back meets both criteria; the construction is aesthetically compatible with the associated cabinetwork and the jointed framework competently resists racking. As a bonus, the floating panels, being unlikely to split, better protect the valuable books contained within from the ingress of dust.
My apologies; this has all been an apodictic but rather verbose justification for my adopting a panelled back for the cabinet!
The rebates in the back edges of the carcase sides were made deeper than those in the chest to accommodate the 3/4″ thick pine panel framework. The fielded panels are each made up from two 1/2″ thick boards, rubbed together with glue. Once glued and assembled, the panelled back was attached to the carcase, as tradition would have it, with screws rather than nails.