Press Fit

A press fit joins two parts through friction alone, with one piece sized very slightly larger than the opening it's driven into -- tight enough that assembly takes deliberate force, but not so tight that driving it in damages either part. It shows up wherever a mechanical fit needs to hold without glue or fasteners: a dowel slightly oversized for its hole, a knob's metal insert pressed into a drilled recess, a machine part fitted to a shaft.

Getting a press fit right is a matter of a few thousandths of an inch, not the eighth-inch tolerances most woodworking gets away with -- too loose and there's no real grip; too tight and forcing it in can split the receiving material. It's one of the places a vernier caliper earns its keep over a tape measure.