Mortise and Tenon Joint: :
The Mortise and Tenon Joint is for structural members and, more specifically, for use in construction of wood structures. It drills a flared round mortise, which makes the bottom of the mortise wider than the top.
You cut a slit into the tenon (Figure 3), insert the skinny edge of the wedge before you drive the two together. It forces it into the tenon. Figure 4 shows the end result.
The bottom of the dovetail expands when power is applied to the drill or router, cutting flared bottom in mortise (Figure 2-B). The relative dimensions of the mortise, tenon and wood members may be varied depending on the application.
Figure 1:  Side sectional view of a first member
including a round, unflared mortise:

Figure 2-A and 2-B:  
Close-up side view of an exemplary bit for use in forming a joint;
the bit is contracted:
| Figure 2-A: | Figure 2-B: | ||
|  | Insert dovetail mortising bit into mortise. |  | Bottom of dovetail mortising bit expands when power is applied to drill or router, cutting flared bottom in mortise. | 
Cutting ridges do not reach the bottom of the bit. This keeps the bit from making the mortise deeper than originally cut.
Figure 3:  An exploded side sectional view of an exemplary joint,
showing a first member including an exemplary flared dovetail mortise and a
second member including a slotted tenon with a wedge disposed in the slotted
tenon:

Figure 4:  Side sectional view of an exemplary joint: 

The inventor is looking for a licensee
Inventor:  Joe Pescatello, 350 Sagamore Rd., Rye, NH 03870
E-mail:  [email protected]