The dado, rabbet and plow are fundamental cuts used within woodworking projects. These three cuts provide groves within the workpiece to make joints. The dado is a square groove cut across the grain of the workpiece. The plow is a square groove cut with the grain of the workpiece. The rabbet is a square open-end groove cut at the end of the workpiece.
The dado and plow are most generally cut using a router and a straight bit. The rabbet may be cut in the same manner but many woodworkers prefer a router with a piloted bit. Other options for tools to make all three cuts are a table saw or a radial arm saw. A special dado-cutting blade is used by some individuals. Others prefer to use an ordinary circular saw blade set to the desired height. The dado, plow or rabbet is cut into the wood by making numerous passes over the blade.
The optional dado blade set consists of two circular saw blades that sandwich together a set of chipper blades. The width of the cut is adjusted by adding or subtracting chipper blades between the two outer circular saw blades. This type of blade requires an extra-wide saw throat plate when used in a table saw.
To make a perfectly straight dado or plow cut in a workpiece with a router requires the use of a guide. The guide is simply a straight piece of wood clamped to the workpiece at the proper location. When using a guide it is important to accurately measure and place the wood guide prior to clamping. Measure the distance from the center of the straight bit to the edge of the router. Measure from the center of the desired placement of the dado or plow groove this distance. Clamp the edge of the guide board to this mark. Cut the dado or plow groove by placing the router against the guide board and move across the workpiece.
Make a rabbet cut in the end of a workpiece using a router, straight bit and guide. The guide is clamped to the router and moved along the edge of the workpiece to cut the proper depth rabbet cut. The guide must have a recess cut in one edge to accommodate the spinning of the router bit. Clamp the guide board to the bottom of the router. Make sure the guide board is at least four inches wider than the router base. Center the recess in the middle of the board. This will ensure an equal distance of guide board is extending past the edges of the router when cutting.
Make multiple passes with the router bit when cutting dadoes, rabbets or plows. Trying to cut the entire depth the first pass may cause the workpiece to chip or splinter. It is best to make multiple passes and cut away a small amount of wood with each pass. This will ensure a square and even cut.
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