Hole making-section 3 unit 6

A 3/8-16 threaded hole needs to be tapped 1/4" deeper. How many turns of the tap are needed to gain that 1/4" of depth?

1 divided by 16=.0625 ; .25 divided by .0625=4 turns

What is the TPI of a 1/2-20 thread?

40 TPI

What is a counterbore?

A counterbore increase the diameter of a hole to a certain depth in order to allow a screw head or a nut to be flush or below the workpiece surface.

What is the purpose of a pilot on a counterbore?

It is to keep the counterbore bit aligned in the existing hole.

what should be done as a drill nears the "breakthrough" point during drilling?

Lighten up on the pressure to prevent grabbing

Define thread as it relates to benchwork

Spiral groove made on a round external or internal diameter.

Name two types of tap wrenches

T-handle tap wrench and straight tap wrench

Explain the major diameter of a thread

The end to end of the spiral of the thread

What are two reason why a hole may need to be countersunk:

To be flush with the surface of the part and to create a chamber.

WHat factors might determine when a hole must be finished by reaming?

is the process of finishing a hole to a precise size. It must also have a smooth finish surface.

Define Drilling:

is the process of using a cylindrical rotating cutting tool that is sharpened on it's end to create a hole.