Shop Notes Cutting Coves on a Table Saw
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1

The surface of a cove molding curves "in;" it's a concave shape. It's commonly used as frame molding, where it gives the framed item the illusion of depth, or around the top of a furniture case giving it height. When combined with a bead molding, the concave surface of the cove molding and the convex surface of the bead molding create an "S" shape and form a classic crown molding. This particular cove molding was not cut with a router or shaper, but on a table saw by passing the wood across the blade at an angle.
2 To set up to cut the cove, you're going to need a set of parallel rules. If you don't have a set, you can easily make them from a few scraps of wood following the plans posted on the Blackboard.
3 Determine the width and the depth of the cove you want to cut. Set the parallel rules so that the distance between them is equal to the width of the cove. Set the table saw blade so that it protrudes above the table the same distance as the depth of the cove.
4 Place the parallel rules on the table saw over the blade. Without changing the distance between the rules, adjust their angle and position until the saw blade barely brushes the inside surfaces of both rules as you slowly rotate the blade by hand. Do not turn the saw on! The angle at which the parallel rules are resting when saw teeth brush both rules is the angle at which you want to pass the wood over the blade.
5 Trace the inside edges of the parallel rules on the saw table. These mark the two edges of the completed cove after its last pass across the blade. The line closest to the infeed side of the table is the "infeed line." The other, closest to the outfeed side, is the "outfeed line." Determine the distance from the edge of the cove to the edge of the molding stock. Mark this distance from the infeed line at several points.
6 Lower the saw blade just below the table. Clamp a straight edge to the saw table, lining it up with the marks you've just made. This will serve as a fence to guide the stock as you cut the cove. Important safety note: You must feed the stock against the rotation of the blade and the rotation should help top hold the stock against the fence as you cut.
7 Raise the saw blade so that it just barely protrudes above the table (1/32" to 1/16"). Turn the saw on and make a test cut in the face of the stock. Check that the cut is centered in the area where you want the completed cove. If it isn't, adjust the position of the fence, raise the blade slightly (1/32" to 1/16") and make another test cut.
8 Cut the cove in several passes, cutting no deeper than 1/16" with each pass. Guide the wood with a push shoe of a push stick as you work.
9 When you have just 1/16" of stock to remove, make your last two passes very light, removing no more than 1/32" with each pass. Also, slow down your feed rate. The light cut and the slow speed will leave a much smoother finish and you'll have less sanding to do. If the molding is symmetrical, reverse the stock end for end on the last pass. This will even out any inconsistencies in the cove from side to side.

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