Lew Hodgett wrote:
"Brian Henderson" wrote:

Most modern glues are stronger than the woods we use them on, if
something fails, it's invariably the wood, not the glue itself.
Therefore, the consideration, as you point out, is the joints we
use, we cannot put forces on the joints that exceed their breaking
strength and far too many people overestimate the strength of joints
because they're fast or easy.

Having spent a few years doing machine design in my youth, was taught
to avoid depending on a weld or fasteners alone to carry the load.

As a result, joints were designed to put the material in compression
and welds were designed to be in shear.

The same design concepts apply to wood and adhesives used in
furniture/cabinet designs.

Glue joints are very strong when placed in shear.

Glue joints are not nearly as strong when placed in tensile loading.

Simple and straight forward, but sometimes we forget to apply the
basics.

Further, the statement that "the glue is stronger than the wood itself"
applies to commonplace species of wood glued into face grain. Gluing some
of the exotics is problematical, and gluing end grain is as well. Note that
in the Fine Woodworking test the butt joint was the only one that failed in
the glue line.

Then there's the issue of creep--keep PVA under constant load and it moves,
slowly, if the design of the joint doesn't prevent it from doing so.