Machine Processes Section 3 unit 1
Briefly explain the benefit of a position tolerance over a traditional linear tolerance.
A position tolerance is used to specify the center of features such as holes or slots. For that reason, position feature control frames frequently contain more than one datum whereas a linear tolerance might use one datum or none.
Briefly describe the difference between a specified and an unspecified tolerance.
A specified tolerance is shown directly next to the dimension and applies only to that dimension. An unspecified tolerance is determined by information in the tolerance block area of the title block.
The line type used to show edges of an object that can be seen in a particular view is called a(n) _________ or __________ line.
object or visible lines
List and briefly describe the three types of tolerances used on prints.
Bilateral tolerances allow a dimension to vary both above and below basic size. Unilateral tolerances allow a dimension to vary either above or below basic size, but not both. A limit tolerance does not use the plus or minus symbols. Instead of a basic dimension listed, the upper and lower limits are shown.
A plane used as a reference for dimensions is called a __________.
Datum
A GD&T symbol and the amount of tolerance are shown in a __________.
Feature control frame
What view of a drawing usually shows the most detail?
Front view
What does GD&T stand for?
Geometric dimensioning and tolerancing
Define and briefly describe the following notations used on engineering drawings:
TYP: TYP is short for typical dimensions and is added when there are multiple, identical part features or equal dimensions. EQL SP: EQL SP stands for equally spaced 3X: 3X would be placed before a hole dimension to say that the 3 holes are the same dimension
Information such as tolerances and scale can be found in the __________ of an engineering drawing.
Title block
Label the views shown in the sketch:
a. front b. top c.right d. bottom e. left f. back
Identify the line types labeled in the print located on the following page:
a. leader line b. dimension line c. extension line d. visible line e. hidden line f. section line g. center line
A dimension listed on an engineering drawing is known as the _________.
basic size
The relationship between sizes of mating parts is called _________.
class of fit
What two line types work together to show sizes on an engineering drawing?
dimension and extension line
What are the five categories of symbols used in GD&T?
form, profile, orientation, location, and runout
What line type is used to show edges of an object that cannot be seen in a particular view?
hidden line
