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.
