The axis of a screw is the longitudinal centerline through the screw.

Pitch is equal to 12 divided by the number of threads per inch.

The form of a thread is the cross section of the thread cut by a plane containing the axis.

Thread length, finish, and proportions are some of the standard characteristics of bolts and nuts.

ANSI has established three classes of fit.

Springs may be classified as either helical springs or flat springs.

Multiple threads are composed of one ridge, and the lead is equal to the pitch.

A Class 3 fit is exceptionally high quality and recommended only when high cost of precision is warranted.

A torsion spring is a type of helical spring.

An internal thread is a thread on the outside of a member.

Keys can be used to prevent movement between shafts and wheels.

Rivets are not considered permanent fasteners.

A machine pin is a mechanical device designed to store energy when deflected and to return the equivalent amount of energy when released.

Doubled threads are composed of two or more ridges running side by side.

Tap drill depth does not include the cone point of the drill.

The root is the top surface joining the two sides of a thread.

A screw thread is a ridge of uniform section in the form of a helix on the external or internal surface of a cylinder.

The major diameter is the largest diameter of a screw thread.

This is the smallest diameter of a screw thread:

These include taper pins, straight pins, dowel pins, clevis pins, and cotter pins: