Wedges provide a bit of extra security in a leg joint. If the glue ever fails, the mechanical power of the wedge will hold the chair together longer.
I prefer a wedge with 4 degrees of taper. This shallow taper has a lot of power. However, you must get the thickness at the entry of the wedge close to the right thickness. If it is too thin, the wedge will bottom out in the joint before reaching its proper tightness.
Begin the process by surfacing wood to the thickness of the width of the tenon. A 1” tenon rquires 1” thick stock. Wedges need to be cut with the grain to remain strong. Crosscut a piece of wood to the final length of the wedge. This wood is then ripped on the tablesaw using the miter guage with an auxiliary fence.
Set the miter guage to 2 degrees. Make the first cut and throw the wedge away.
Flip the wood over.
Make another cut. Make a mark on the auxiliary fence to reproduce wedges with the same thickness.
Here’s what the wedge looks like right off the saw.
This stack of wedges will hold the the seat tenons in place on two rocking chairs.
The wedges need to run perpendicular to the grain. If they run parallel to the grain, they will likely split the seat or the rocker.
Marking out the seat tenon.
Marking out the rocker tenon.
I have cut the kerfs by hand on some previous projects. However, I like to cut them on the bandsaw with a V-block now.
Here’s a view of the technique in action. The roller stand keeps the V-block steady. The v-block keeps the leg from rolling.
Sight the blade with your mark to ensure correct orientation.
Close-up of a cut. I make a slight wedge-shaped cut for the seat tenons and a simple kerf for rocker and spindle tenons.
A chair’s-worth of legs kerfed and ready for assembly.
I need to complete the rockers next…
-- Mark, Minnesota