Dewalt D26202 glodalica vertikalna dvoručna 900W prihvat 6-8mm

Woodworking - The Pivot Joint

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By John English

A sure sign of superior craftsmanship, integrated wooden hinges have been part of the cabinetmaker’s portfolio for at least two millenia. Apart from the obvious aesthetic advantage, a wooden hinge also can be glued directly to parts for an incredibly strong joint. Wooden hinges can be formed easily to fit unusual shapes or spaces - a real boon when designing contemporary furniture. But the most appealing aspect of a wooden hinge is still its visual impact. Whether you use a contrasting species to make them jump out, or a matching one that allows them to blend in, wooden hinges always add a distinct elegance to any design.

Select and cut your stock
Grain direction is a big factor when selecting stock for hinges. This is especially true with wide-grained species like oak or chestnut, that move a lot as they react to changes in humidity. Tighter species like walnut, cherry and maple will present fewer problems in the area of binding and warping. The grain in a hinge should run the same direction as the workpiece to which it will be glued. The grain patterns should also be similar enough that they don't expand or contract at different rates, as this will stress the joint that holds them together.

Plan your hinge width so that it can easily be divided equally: if you want four sections in the barrel and the width is 2-3/16", you may have a problem. You also have to drill the barrel for a pin, so make sure the width doesn't exceed the length of your drill bit. Planed 4/4 stock (rendered at 3/4" thickness) is ideal for hinges. It's not too bulky, yet it is thick enough to be strong.

As with all joints, I advise making a few test pieces before milling your precious hardwoods. 

Round over the ends The first machining operation is to bullnose one end of each hinge. For 3/4" stock, chuck a 3/8" radius bullnose bit in a table-mounted router (minimum 1.5 HP), then set your fence. Remove the waste in three equal passes, to avoid stressing the bit or the router. You could also make this cut with a roundover bit and a fence. In this case, don't rely on the bit's guide bearing as the first cut will remove part of the bearing surface, so the second cut will not be accurate. You must use a fence.

Plow Two V-grooves Use a sharp pencil and a compass to draw a 3/4" circle on one edge of the bullnosed stock. Then chuck a V-groove bit in your router and plow the 1/8" deep groove that separates the barrel of each hinge from the leaf. The location of this groove is critical (as shown in the illustration, below). It just touches the pencil line you drew with the compass. After making the cuts, use a sharp file to remove the remaining small amount of stock between each V-groove and its barrel, thus making the barrels fully round. Sand each hinge with the grain, using 180 grit paper.

Create the fingers

The interlocking sections of the barrel can be milled much in the same way that a traditional finger joint is created. Install a dado head (the photo shows a 3/4" wide setup for our 3" hinges) in the table saw, then attach a tall auxiliary fence to your miter gauge. Set the dado head's cutting height at 3/4" and make a pass, cutting a groove in the scrap fence. Use a pencil and a try square to mark a vertical line on the fence. This is to the operator's right of the groove, and exactly twice the width of the cutter away from the cutter. (In the photo, our line is drawn 1-1/2" from the cutter.)

Make your first cut in the right edge of the piece, then move the workpiece to the line and clamp it in place as you make your second pass. If you go with either three or five sections in the barrel, adjust your setup accordingly.

Drill for the Pin

Assemble the hinge on the drill press and clamp it in place. Center the bit on the barrel. A 1/4" bit and pin work well with 3/4" thick hinges. Drill the hole a little over halfway through the barrel, then turn the hinge upside down so the bottom edge becomes the top. Clamp it back in place, center the bit and complete the hole. This will ensure that any tiny variance in your drill press is taken into account, so the pin is centered in the barrel.

Slide a hardwood dowel into the hole, leaving one end of it a little shy (about half the width of a barrel segment). Apply glue to the exposed dowel, then tap it home.

For projects that will recieve excessive use, epoxy a length of brass rod into the barrel, instead of the hardwood dowel.

Final Fitting
After the glue (or epoxy) dries, sand each hinge down to 280 grit and lightly break the sharp edges and corners. For surface mounting, you may want to reduce the thickness of a portion of each leaf by passing it across a dado head, or resawing on a band saw. Other installations include transforming the leaves into tenons and housing them in mortises chopped in the parts to be hinged, or reducing them to sliding dovetails and setting them in dovetail grooves. Whatever your application, solid hardwood hinges are guaranteed to add visual appeal to your next project. 

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