Engineering graphics test 3

Projection

3-d image on 2-d media

oblique

Face is accurate, other sides are drawn at 45,30,90

cavalier

Full depth (receding like full length)

Cabinet

Half depth (closer to human eye)

Geometric

Specifying and tolerancing the shapes and features of object, size in dimensions, and shape is defined by orthographic drawing

America inches

If more than 72 goes to feet

International System of Units

Based on meters; common length millimeter

degrees

Measured in decimal degrees, radians, minutes, seconds,

dimension

Defines shape, size, location, surface texture, or geometrical features

Dimension Text

3mm or 0.125 inch; space in between lines 1.5mm or .0625"

Basic Dimension

A dimension that is theoretically exact. It is identified by a box around the dimension.

Reference Dimension

The numerical value enclosed in parentheses, used to show intended design, no tolerance

Dimension Line

Thin lines capped with arrowheads, which may be broken along their length to provide space for the dimension numerals.

arrows

3mm long and 1/3 as wide as long (uniform in size)

Extension Line

Shows where a dimension starts and stops, visible gap of (1/16")

Leader Line

Line which indicates dimensions of arcs, circles and detail, text is written at end of shoulder

Limits of Size

The largest minimum acceptable size of a feature

MMC

Maximum Material Condition; The largest size limit of an external feature and the smallest size limit of an internal feature.

LMC

Least Material Condition; The smallest size limit of an external feature and the largest size limit of an internal feature.

Plus and minus dimensioning

The allowable positive and negative variance from the dimension specified

Diameter Symbol

ø

Radius Symbol

R

Tolerance

Amount that a particular dimension is allowed to vary, shown through limit dimensions or plus minus

Spacing

Extension line extend 2mm past dimension line

Extension lines

Break extension line for arrows and do not break when going through object (center lines can be used as extension lines)

[_]

Counterbore

V

Countersink

Line with arrow under

Depth

Nominal Size

General size, usually in common fractions

Basic Size

The theoretical size used as a starting point for the application of tolerances.

Actual size

measured size of a finished part

allowance

the minimum clearance or maximum interference between parts

Piece Tolerance

the difference between the upper and lower limits of a single part

Clearance Fit

Occurs when tolerance parts will always leave a space or clearance ( smallest hole - largest shaft)

Interference fit

Interfere when assembled, fixes or anchors one part into another

Transition fit

Occurs when two mating parts can sometimes have a clearance fit and sometimes have an interference fit.