Section 3___Unit 6___Drilling, Threading, Tapping, and Reaming

General Purpose Reamers

are used for finishing holes to a particular size

Twist Drill

general purpose hand drilling is called

Lead

is the distance a thread will advance in one revolution

Flutes

Twist drill bits have spiral grooves in their sides called ____ that give them appearance of having been twisted

Hand Reamers

are intended to be driven by hand and are fitted with a square driving surface for mounting a wrench

Adjustable Reamers

are similar to expansion reamers, but they have a different construction which allows a much greater range of adjustability

Taper Pin Reamers

are used to create precise tapers within straight holes that allow them to receive tapered pins

External Thread

can be cut on the outside diameter of a work piece with a cutting tool called a Thread-Cutting die

Internal Thread

can be produced in the inside diameter of a work piece with a tool called a Tap

Reamers

cutting tools used for reaming

Tap Drill

drill bit size for a hole prior to tapping

Electric Drill

drill bits may be mounted in and driven by a hand-held electric drill motor

Nominal

for inch series threads the first number shown is the ____ major diameter of the thread

Hand Tap

hand taps cut threads and have straight flutes from the tip toward the shank

Unified Thread Standard

has established the form (shape) and dimensional standards for the consistent interchange of thread parts

Jobber's Reamers

have longer flutes and are useful when reaming deep holes

Expansion Reamers

have slots cut into the body that allow the reamer to expand to the exact size needed when the adjusting screw in the end of the reamer is tightened

Thread

is a spiral groove made on a round external or internal diameter

Thread Depth

is the depth of a single thread measured from the crest to the root

Pitch

is the distance from a point on a thread to the same point on the adjacent thread

Threads Per Inch (TPI)

is the number of threads within 1 inch of the work piece length (INCH SERIES THREADS ONLY)

Crest

is the peak of one thread and creates the points where the major diameter is measured

Countersinking

is the process of cutting a tapered opening in a hole so that a flathead screw can be installed flush with the work piece surface

Reaming

is the process of finishing a hole to a precise size with a smoothed finished surface

Spotfacing

is the process of machining a flat top on a rough surface surrounding a hole opening so that bolts, nuts, and washers will be properly seated when tightened

Minor Diameter

is the smallest diameter of the thread

Root

is the valley between threads and creates the points where the minor diameter is measured

Major Diameter

largest diameter of the thread

ISO Metric

metric threads are standardized also by the ____ screw thread system sometimes simply called M-series threads

Spiral-Point (Gun) Tap

taps also cut threads and have straight flutes with a special angle ground on their ends

Drilling

the process of using a cylindrical rotating cutting tool that is sharpened on its end too create a hole

National Pipe Thread (NPT)

theses threads are taped 3/4 inch per foot to help seal them as they tighten together