Wedges
Wedges are the glue that holds the whole thing together. Actually, you don’t need any wedges if you don’t move around too much or try to move the chair. But I think we all agree that having the parts nice and tight gives us a stable seat on which to plant our…seat. The goal is to have the joint locked together, a snug fit for the wedge without causing damage to either the wedge or the chair. The chairs I build come with a set of wedges specifically fit to each joint and labeled..The labels should be self explanatory and the writing always goes on the back side.
A properly constructed wedge will have a vertical side against the surface to be locked (the chair side for example). The opposite side should have a shallow taper. It doesn’t have to be a lot to provide the locking action. My wedges are typically taper between 1/8″ and 3/16″
A properly fit wedge will lock down at the point where the wedge is approximately centered vertically. Try to avoid knocking the wedge in further than necessary. You will only compress the wood and/or break out the pocket. Once compressed, you will always need to knock the wedge in that far to get a lock.