Chapter 5 - Precision Measurement

Define precision and accuracy and list the two most commonly used systems of measurement.

Precision - the level of accuracy or mechanical exactness.

Accuracy - the degree to which a measurement conforms to a specific standard.

English System and the Metric System.

Explain how to convert a unit without a prefix (base) to a unit with a prefix.

The decimal point in the base is moved to the left or right and a prefix is added.

The decimal point is moved to the left and a prefix is added to convert a large value to a simpler term.

The decimal point is moved to the right and a prefix is added to convert a small value to a simpler term.

Explain how to convert a metric measurement to an english measurement.

Multiply the measurement by the number of English units that equal one of the metric units (conversion factor).

Angle

A geometric figure formed by two lines extending fron the same point.

Ray

A straight line intersecting a point (vertex) of an angle.

Vertex

The point of intersection of the sides of an angle.

List three types of measurements calipers are used to take on components.

Inside Diameter (ID)

Outside Diameter (OD)

Length measurements.

Define Vernier Scale

A short auxillary scale placed along the main scale of a measuring instrument to provide accurate fractional readings of the smallest division on the main scale.

List three factors that the accuracy of a micrometer measurement is dependent on.

The quality of the tool.

The care the tool receives.

The skill and knowledge of the techinician using the tool.

Why is the frame of an outside micrometer U-Shaped?

To allow the anvil and spindle to fit around a workpiece.