Shaping with a Table Saw

The simplest of all shaping operations — a 1/8" groove with a standard (ATB) blade.

Sawing a square rabbet with a standard blade using the saw fence. To get a constant, clean corner, the workpiece must have a face side and face edge (left). Sawing a rabbet with a dado blade using the miter gauge fence, with the workpiece clamped for accuracy and safety (right).

Mounted in a table saw, a molding head like the one shown (top right) will shape a decorative edge on a furniture part. The decorative edge also can be ripped from the rest of the piece to create decorative moldings.

Shaping with the router

It's possible to cut a circle using a router, an extended base and a pivot. In this case the guide is a point, not an edge.

A router fitted with a guide bushing also can be used to cut a curved head rail for a raised and fielded panel. The bit can be adjusted to cut just beyond the depth required.

The term "shaping" includes any operation to modify parts and create details that does not separate the wood into two pieces. Common shaping operations include making grooves, rabbets, dadoes and moldings as well as raising panels and shaping edges. Shaping is accomplished with a regular saw blade, a dado head or a molding head on a table saw and with bits of various profiles in a router.

Most shaping operations can be done in more than one way. For example, you can make a rabbet with two passes of the saw blade, with one pass over a dado head or with one pass using a rabbeting bit in a router. Deciding which way to proceed involves the tools available, the amount of wood that must be removed, the number of passes required to remove all of the wood and the number of pieces you intend to machine. It's always best to minimize the number of passes across the saw blade or cutterhead. Each additional pass increases the risk of error.

For accurate results, the workpiece must first be surfaced with a face side and face edge. Routinely prepare extra stock for test pieces. An alternate top bevel (ATB) or flat-top carbide-tipped saw blade can be used for shaping on the table saw.

The blade height depends on the shape you want to make. To ensure the consistency and accuracy of the cut, focus your attention on tight contact between the workpiece and fence. When shaping with a regular saw blade, you can use the regular table insert. Dado heads and molding heads, however, require inserts with wide slots.

Here are some common shaping operations on the table saw:

Sawing grooves — The simplest groove is one pass along the fence and over the saw blade. To make wider grooves using a standard blade, make the two outer cuts first, then make multiple cuts to remove the waste from the middle. Wider grooves are best done with a dado head.

Sawing rabbets — A rabbet is a rectangular cutout along the corner of the wood. A dado head makes cutting these quicker.

Sawing dadoes — A dado is a groove made across the grain of the workpiece. It's possible to do this with a regular saw blade, but a dado head will speed this operation.

Molding head — A three-knife molding head that mounts on the saw arbor gives the table saw some of the capability of a shaper. You can profile the faces and edges of furniture parts as well as run quantities of moldings for carpentry.