Dowel Joint

Dowel alignment is critical. Use plunge router jig.

FIG. 4: DECORATING EDGE JOINTS

Solid and veneer inserts, in harmonious or contrasting colors, create design elements.

Draw on wood with veneers glued into handsaw cuts.

Veneers follow flow of grain.

Draw on wood with veneers glued into handsaw cuts.

Veneers follow flow of grain.

Heart Side or Bark Side? Bah.

Much ink has been spilled about controlling cupping by which way up the boards go. Do you want them all heart side up, or bark side up, or alternating, or what? Perhaps this was a problem back in the old days, when wood was wide and erratically seasoned. Today you can't get those wide boards, but what you can get is likely to have been seasoned properly. Therefore, in most situations, you can quit worrying and go for what looks best.

In unusual situations, where you really aren't sure about the wood's moisture contcnt or when you anticipate moving from Seattle to Santa Fe, you have only three choiccs about which way to arrange the wood:

All boards same way up—If the boards cup, they all go the same way and the whole panel takes on a curve. There isn't much force in it, so a couple of screws will pull the panel down flat. You might favor this tactic if you were making a supported structure, like a lcg-and-apron tabic.

Alternate heart side, bark side—If there's any cupping, it'll show up as ripples, but they won't be very big. You might follow this approach when making table leaves, fall-flaps and other unsupported panels.

Go for good looks—Even in unusual conditions, you can design your way out of distortion by restraining the glued-up panel. This is one of the reasons for making frame-and-panel furniture, and for dovetailing the tops to the sides of cases. You can forget about heart-side bark-side and concentratc on chc look you want.

Aligning the Joint

With well-prepared boards and some clamping practice, you can glue up most wide panels without mechanical alignment. When the wood is bowed in length, or the assembly has a lot of parts, you may need splines or biscuits.

From a design point of view, biscuits have the advantage of not showing on the end grain, whereas the spline docs show if you run the slot right through. Otherwise, the two processes achieve the same alignment.

Cut the spline slot on the tablcsaw. Make it the width of the carbide blade and to a depth of about Vl6 in. in each board. I usually try to center the spline in the thickness of the edge, but it doesn't matter, provided you can keep the same face of every board to the fence. You can make the splines out of the same wood as the panel, or you can use a different wood; my preference is hard maple because of its strength and uniformity. Make the splines a snug fit in the grooves, with perhaps V64 in. of depth clearance. Be sure you brush glue down into the slots and roll glue onto the spline itself.

A single row of biscuits is enough. Though they don't permit up-and-down movement, there's a surprising amount of end play. Use #20 biscuits and space them between 8 in. and 12 in. apart. To cut the slots, jig the sole of your biscuit joiner off the bcnchtop. (Sec Fig. 3.) As long as the board is flat and you hold it tight on the bcnchtop, the slots will be the fixed distance from the machine's sole to the cutter from your reference surface. Always spread glue on the biscuits as well as in their slots—it won't transfer from one surface to the other.

Dowels or tongues cause problems. I don't rccommcnd using cither of these for aligning edge joints. Milled tongues, like the shaped gluc-joint made with a spccial router cutter, just waste a lot of wood with no advantage. Dowels arc almost impossible to keep parallel, so they'll forcc misalignment into the joint. They also introduce a cross-grain clement. Even so, if you get them right, dowels do work. But splines and biscuits work better.

Decorative Enhancements

With well-chosen wood and good edge-joining technique, a long-grain glue joint virtually disappears. You don't see the glue itself; you see only a discontinuity in the wood's figure, and if the color matches, you'll have to look hard to find it. You've created an ideal wide board, one you couldn't have found elsewhere.

But wide and perfect might not be what you want. You might want to introduce such design elements as line, pattern, color, shape, and texture. For example, it's usual to shape the long sides and the ends of tops. You can also choosc to emphasize the glue lines, with inserts of veneer or of solid wood, in harmonious or contrasting colors. And you can glue up along curvcd lines, with or without vcnccr inserts. (Sec Fig. 4.)

Veneer inserts offer many design possibilities. Though you should learn the technique with a single thickness of veneer, it's worth experimenting with multiple layers from a palette of colorful and dyed woods. Take a look at cherry with a thrcc-vcnccr insert, black-color-black. Or maple with a triple thickness of a strong primary-colored veneer.

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