: a hole for a tap specifically : a hole at or near the bottom of a furnace or ladle through which molten metal, matte, or slag can be tapped.

What is a tapping hole used for?

A tapped hole is a hole drilled prior to a machine screw being inserted. A tapped hole is similar to a pilot hole, except that it is usually larger, and has threads cut into the inside surface of the hole. Tapped holes are used in metals where a nut and bolt cannot be used.

What does it mean to tap a hole screw?

Tapping is the process of cutting a matching set of threads into a piece of metal, plastic, acrylic, or wood. The process of tapping uses two separate tools: the tap which cuts the threads on the inner diameter of the hole, and the die which cuts the threads on the outer diameter of the bolt or screw.