Wooden Grooving and Rabbeting Planes

BY KERRY PIERCE

A tablesaw equipped with a dado set is brutally efficient for cutting dozens of grooves, dadoes or rabbets. I tend to build just one piece at a time, though, so I rarely find myself faced with making such a large number of joints. More typically, I need dadoes for two or four shelves, and I turn to an old set of wooden dado planes. I also use antique wooden planes for cutting grooves and rabbets–I believe that all are useful in the modern shop. So too are their metal-bodied equivalents, which I’ll talk about in a future issue.

THE PLOW PLANE

There are three different kinds of square channels typically used in casework: the groove, which is plowed a distance from the edge in the direction of the grain; the rabbet, which is cut along the edge either with the grain or across the grain; and the dado, which is cut across the grain. There’s a specific plane best suited for each of these cuts.

The plow plane is the hand tool of choice for cutting grooves. Plow planes were typically equipped with a set of eight interchangeable irons graduated in 1/16″ increments from 1/8″ to 5/8″ (skipping 9/16″). Unfortunately, plows are almost never found with full sets of irons. I own about a dozen plows, and each one came to me with only a single iron. However, it is possible to buy loose irons from tool dealers and on eBay, and in that manner assemble a set. But I should warn you: Not all irons will fit all plows. The closest I’ve come to a full set is a group of five different irons for my Ohio Tool plow (1).

You may need to recondition an old plane before you can use it (see my article “Restoring a Wooden Plow Plane,” Woodwork #97, February 2006, p. 72), but they are simple tools to understand and adjust. In some plows—usually the English ones—the arms and fence are held in position by wedges tapped into tapered mortises cut in the sides of the arm mortises (2, rear). The arms and fences of early American plows are often held with thumbscrews (usually made of boxwood) passing down through the plane’s body to make contact with the fence arms (2, right). Later—and in my view, better—American plows are equipped with threaded screw arms, also made of boxwood. The arms pass through unthreaded mortises in the plow’s body (2, left and front). The fence is held in position by trapping the plane’s body between threaded boxwood washers and larger threaded boxwood nuts (3). In this photo, these parts are laid out in order of assembly.

A plow plane is fitted with a moveable depth stop that can be set to create grooves up to about 1″ deep. In photo 4, the depth stop is the metal shoe visible behind the skate. It’s raised and lowered by a brass thumbscrew on top of the plane and locked with a second thumbscrew on the plane body’s left side. Different plows have different styles of depth stops. The early American plow on the right in photo 3, for example, has a depth stop that’s a piece of boxwood friction-fit into a vertical throughmortise in the plane’s body.

A plow plane iron is quite heavy on the business end, 1/4″ or more, tapering to less than 1/16″ at the top of the tang. Sometimes the tang is snecked (a sneck is a metal tab that may be tapped with a hammer to adjust the iron). The iron is held with a tapered wedge and is typically bedded at 45° to 50°. Each iron has a groove milled into the center of its back that fits snugly on the plane’s metal skate (4). This arrangement stabilizes the iron.

Plow plane blades are sharpened like ordinary plane blades. You may have difficulty removing a stuck iron, though. Here’s how to do it: With the thumb and forefinger of your off hand, grasp the iron’s tang and the finial at the end of the wedge (5). Tap the plane’s heel with a hefty mallet, in effect driving the plane off the wedge and iron. If this doesn’t work, clamp the wedge’s finial in a vise and drive up the body with mallet blows. (Be careful, to avoid cracking the wedge.)

When you install a sharpened iron, make sure that its groove engages the skate. Turn the plane over, sight along the skate and position the iron so that its cutting edge just barely peeks above the skate. Then tap the wedge firmly in place with a wooden or hard-rubber mallet (6). Some craftsmen used metal mallets or hammers, but I’ve seen a lot of damage from them, including mushroomed tangs on irons and broken finials on wedges.

Next, set the fence. Determine the desired distance between the edge of the board and the outside edge of the groove, then set the fence by measuring the distance from the inside edge of the iron to the fence. Snug up the washers on the left-hand side of the plow’s body. Next, check that the fence is parallel to the skate. First, measure the distance from the inside edge of the skate to the front portion of the fence (7). Make the same measurement at the back of the fence and compare numbers. If they’re different, adjust one of the washers. Once the fence is parallel, tighten the nuts to trap the plane’s body against the washers.

You’re ready to apply the plow to the wood. With your left hand, press the fence against the board’s edge. Press the skate (and the cutting edge) down onto the board with your right hand. Using both hands, push the plow forward (8). Some users prefer to start a groove at the far end of a board and work backwards, but I’ve always started at the near end of a board and haven’t had any problems. If this is your first time using a plow, I can almost guarantee that your depth of cut will need to be reset. A proper shaving will be thin enough to curl but not quite as thin as one made by a smoothing plane.

RABBET PLANES AND MOVING FILLETSTERS

Wooden rabbet planes are simple tools: they’re just comprised of a body, blade and wedge (9, right). They must have been widely used in the 19th century, judging by the number of antique planes around, but I prefer a more sophisticated tool: the moving filletster (9, left and center). These planes have fences, depth stops and slitters. The blades in rabbet planes and moving filletsters are flush with the right side of the plane’s body, so you can work right up to an adjacent surface. Some irons are square to the plane’s body, but many are skewed.

A rabbet plane doesn’t have a fence, so you must clamp a batten to your workpiece to guide it. A moving filletster’s fence is different than a plow plane’s fence. On my planes, it’s a 2″ wide board attached to the sole via a pair of large screws (10). Adjusting the fence is a simple matter of loosening and tightening the screws, but, like the plow plane’s fence, you should measure in two places to be sure that it’s parallel to the plane’s body.

On a moving filletster, a slitter, or nicker, scores the wood ahead of the iron (11). This blade is particularly important when you’re cutting a rabbet across the grain, in order to make a clean cut. My planes have different slitters: on one, the slitter is wedged in place like a conventional plane iron; on the other, it’s a length of tapered metal fixed into a dovetail-shaped mortise. Slitters must be sharp, and are installed so the bevel faces in. Adjust the slitter’s exposure so that the point extends from 1/32″ to 1/16″ below the sole.

Both of my moving filletsters have skewed irons which must be carefully ground and sharpened to maintain the correct skew angle. When you install the iron in a rabbet plane or moving filletster be careful to position it so that its right outside corner is perfectly aligned with the right-hand side of the plane. Ideally, you’ll want a bit more exposure of the cutting edge through the sole than you would with a smoothing plane.

To cut a rabbet with a moving filletster, crowd the fence against the edge of the stock being rabbetted with your left hand (12). Then, with your right hand applying both downward pressure and forward movement, begin taking shavings.

Cross-grain rabbets require extra preparation. In order to prevent the plane from tearing out fibers at the end of each stroke, clamp a backer board onto the far edge of the stock (13). When you’re working with a relatively brittle species you might want to first score across the grain with a sharp knife, in order to cut deeper than the slitter.

DADO PLANES

Dado planes come in a variety of widths, usually in 1/8″ increments from 1/4″ to 7/8″. They are significantly more sophisticated than rabbet planes, but of course they don’t have fences like a moving filletster. A dado plane has two irons–the primary iron, which cuts the shavings, plus a secondary iron in the front of the plane that scores the wood on both sides of the cut (14). The primary iron is skewed, while the secondary iron is really just a pair of slitters ground on the end of a rectangular blade. The slitter iron is the full width of the dado, and is sharpened so that the bevels face in. Dado planes also have depth stops of various designs.

While I love using wooden dado planes, it does take some thought to set up a cut (15). A dado plane must be guided by a batten, so in addition to fixing the stock between bench dogs, you must also clamp or tack a batten beside the dado you wish to cut. Plus, because dados go across the grain, you should clamp a backer board to your stock in order to avoid ripping out long splinters when you complete your cut. As you can see in photo 15, a wooden dado plane lifts clean cross-grain shavings between the scorings left by the slitter iron.

WORKING IN THE LIGHT OF HISTORY

The truth is, I don’t choose to use these hand tools because I’m looking for greater efficiency. I use them for other, in my view, more compelling reasons. Foremost among these is a direct and concrete connection with the history of my craft.

My A. & E. Baldwin moving filletster (16) was made in New York City between 1830 and 1841. It was likely used in that city or its environs during the first years of its life by a craftsman whose name is now lost. The plane traveled from New York to Ohio during the next 175 years, perhaps stopping along the way to provide service in the shops of several other craftsmen. Every time I pick up the plane and apply it to wood, I am connected to those woodworkers. When I smile at the site of a shaving curling up from the plane’s throat, I imagine a similar smile on the face of the craftsman who first used this tool somewhere in New York, a long time ago.