A heavy straight line should be drawn under all dimension values that are to scale.

When extension lines or centerlines cross visible object lines, gaps should not be left in the lines.

Most mechanical drawings will include tolerance information in or near the drawing title block.

In a group of parallel dimension lines, the dimension values should be staggered.

The inch is the commonly used unit for most metric engineering drawings.

The American Society of Mechanical Engineers provides a set of common standards used by industry for placement of dimensions.

Longer dimension lines are nearest the object outline.

When designing mechanical devices, the designer must consider what the allowable variation in size between mating parts can be.

By adding dimensions to a technical drawing the drafter is providing information about the size and location of features of a part.

An extension line is a thin, dark, solid line that extends from a point on the drawing to which a dimension refers.

A metric dimension that is a whole number does not show a decimal point or a zero.

Fillet radii can be given in a general note.

It is permissible to letter a dimension value over any line on the drawing.

It is more difficult to manufacture a part designed using two decimal places than the same part using four decimal places.

An external cylindrical shape is dimensioned where it appears circular.

Where the decimal-inch dimension is used, a zero is not used before the decimal point of values less than 1.

The nominal size of a feature is the exact measurement of the feature after the tolerance has been applied to it.

Dimension lines should not cross extension lines.

It is always acceptable to dimension to a hidden feature.

Drawings are usually made to a scale, which is indicated in the title block.