Laying Out The Mortise

hinge placement

. Center of hinge pin should fall within

Scribe against ends of hinge with knife.

machined, these hinges have a pleasing heft (even when tiny) and don't rattle around like stamped or pressed butt hinges, which are made by wrapping sheet brass around a pin. Like a lot of old-fashioned things, extruded brass hinges can be hard to find. Most hardware stores carry only stamped or pressed brass butt hinges. You can get them by mail order from any of the sources mentioned. (See Sources.)

How many hinges? For most boxes, chests and cabinet doors, two hinges are enough. However, a third hinge in the middle can pull a slightly bowed lid or door into position or give added support to an especially heavy lid. I place hinges at least their own length from the ends of a lid or door, but appearance determines placement as much as anything does. The techniques I mention in this article apply to boxes, doors, and chests, but from now on. I will only refer to boxes.

What size? Hinges come in a variety of combinations of length and width. Most catalogs specify by length and open width, in that order. I like to house the hinge in a stopped mortise and to have the knuckle protrude outside the box as little as possible, while still permitting the lid to open fully. To accomplish this, the open width should be equal to or slightly less than twice the thickness of the box side. For a given hinge width, there are often several different lengths available. Longer hinges provide more support, but I frequently select a shorter hinge because it looks better.

Installing butt hinges is fairly simple. I use a marking gauge (or two), a couple of sharp chisels, a mallet, an awl, a hand drill, and a screw driver. The photos tell the story.

Plane the lid and box so there are no gaps between them. Set a marking gauge for the width of the mortise and one for its depth. (Two gauges allow you to do the whole job without resetting.) I set both gauges just shy of the pin's centerline. Wider than this, and the lid won't open completely; narrower, and the protruding knuckle will look bad. Deeper, the lid won't shut; shallower, the gap will be unsightly. The centerline of the hinge pin should fall within the shaded quadrant shown in the drawing above. If it falls below, the lid won't shut. If it falls to the left, the lid won't open completely.

You can start with either the lid or the box. Make light pencil marks indicating the hinge positions, then scribe the mortise width and depth between them with the marking gauge. Align the edge of the hinge with the width mark, and scribe against the ends of the leaf with a thin, sharp knife. (I use a chip-carving knife.) The ends of hinges are seldom milled perfectly square to their edges, so I mark the leaves and mortises with numbers to keep them matched correctly.

Deepen the scribe marks with a sharp chisel, then score the waste to the approximate depth of the mortise. The mortise tapers from the knuckle to the edge of the leaf, as shown in Fig. 1, so I angle the chisel accordingly. Chopping both across, then with the grain makes the waste easier to remove. I stav about '/« in. away from the scribe marks at this stage.

Pare the waste away with a wide, sharp chisel. Start the final cuts bv nestling the chisel's edge in the scribe mark for the depth. Trim to the knife and scribe lines, then check the fit with the appropriate hinge leaf. Make the final cuts along the inside edge carefully to avoid splitting off the remaining thin piece.

With the hinge in place, use an awl to mark the screw holes. Take some care positioning the holes, particularly in open-grain wood, such as oak. I fudge slightly toward the inside of the box, so the screw will pull the hinge tight to the leaf edge of the mortise. (See Fig. 1.) Bore the pilot holes, then screw the hinge down.(Attach three-hole hinges with only the center screw—the hinge will be on and off several times be-

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