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The Woodwright's Workbook: Further Exploration in Traditional Woodcraft By Roy Underhill
Joining Up Wide Boards
Fitting boards together so that "they shall seem one intire Piece" is Joseph Moxon's 1678 definition of the "Art of Joinery." Planes are the essential tools for edge joining, but without stabilized wood the best planes can do little good. You often need to plane the wood twice, "for It has been observ'd," says the 1734 Builder's Dictionary that "though Boards have lain in an House ever so long, and are ever so dry, yet when they are thus shot and planed, they will shrink afterwards beyond Belief." Only after this initial planing and redrying, when the boards "will shrink no more," may they "be again shot with good Joints."
Think about the orientation of the grain of the boards that you join together. The annual ring pattern on the end grain will tell you how the board will respond to changes in moisture content. Ideally, these rings will be at consistent right angles to the face of the boards. This "quartersawn" stock will not distort with further drying. Arching rings on the end grain, however, indicate boards that will become concave toward the bark side of the tree. Knowing that this will happen with such stock, you can minimize the cumulative effect by placing the boards in an alternating sequence of heart up and heart down. This will give you an undulating, wavelike but generally level surface. In a surface of all heart-up wood each board adds to the deviation of the previous one. Such an arrangement does, however, allow you to save wood because there will be less exposed sapwood to trim off for a good color match.
In 1755 Williamsburg cabinetmaker Anthony Hay placed an advertisement in the Virginia Gazette informing subscribers that, among other cabinetmaker's tools, he was selling "glue jointers." The glue jointer is the long plane, as long as the workbench is tall, that shoots the perfectly straight edges that you need to make the rubbed glue edge joint. If you have ever encountered the remarkable bond created when two wet panes of glass are rubbed together, then you know how the rubbed joint works. The glue bonds the joint even before it sets. The glue jointer's job is to make the edges of the boards as smooth and flat as glass.
The length of the plane serves to ride the cutting iron over hollows in the wood, cutting the high places lower and lower until there are no high places left. When you joint boards, you must put pressure on the nose of the plane at the beginning of the stroke, the tail of the plane at the end of the stroke, and evenly in the middle of the stroke. The length of the plane will eliminate hollows in the board, the shaving emerging in one long, unbroken strip. The only inaccuracy the jointer will commonly allow is gentle crowning. When you place boards with crowned edges together, they will pivot around the middle of their joint. The ends of the boards should drag when the joint is pivoted, and no light should be visible between them.
Simple tricks are the best when they are easier to do than to explain. Edge joining is like this. It is a simple fact that when the edges of two flat boards clamped face to face in the vise are planed as one, the boards are automatically aligned in a level plane when their edges are folded together. Basically, to whatever degree the plane is tilted (and it always is), an equal but opposite error is imparted to both pieces. When the two pieces are folded together, the errors cancel each other out, the boards are flat, and the joint is tight.
When the planing Is right, the glue can do its job. Warm the board if you are using glue from the hot pot. Place one board edge-up in the vise, the edge of the other touching it, and brush the glue on both surfaces at once. Fold the joint closed and rub the two surfaces together until you feel them take hold. Check the alignment and then carefully set them aside to dry overnight propped against the wall. You don't need to use dowels—the joint will be plenty strong. If you want reinforcement after the glue has set, however, heed once more the Builders Dictionary and "let every Joint be secured by two Wooden Dovetails, let in cross the Joint on the Backside." Dovetails, or "butterfly" insets, within your chest show class; use them and your tools won't speak ill of you.
"The Woodwright's Workbook: Further Exploration in Traditional Woodcraft" By Roy Underhill
© 2012 The University of North Carolina Press