Breadboard ends help keep the tabletop flat.
Build sturdier tables by beefing up the basic mortise and tenon
The life of a table is not easy. Legs get kicked; the table gets pushed and pulled across uneven floors, leaned against, and sometimes even sat upon. To make matters worse, the veiy nature of wood adds to the stress. As the tabletop shrinks and swells with seasonal changes in humidity, the movement works against the integrity of the table's structure. All that stress is felt in the leg-to-apron joint (above), which holds a table together and gives it rigidity. When the leg-to-apron joint fails, the table falls apart.
Leg-to-apron joints must withstand three different kinds of stresses: shear, bending, and twisting. Shear stress is caused by a vertical load directly above a joint, such as when someone sits on the corner of a table. Leaning heavily on the top of a table midpoint above the apron causes the joints to undergo a bending stress that tries to lever them apart. Shoving the table sideways or bumping against a leg gives the joints a mixture of twisting forces. Also, as a tabletop that is fastened too tightly to the apron expands or shrinks, it can tiy to twist the joints.
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