students should have gathered all the materials that they will need to construct their Heart Model. 

GD&T symbol used in the United States today.

This is a positional control symbol that should rarely be used. Often it is used because

the symbol itself bespeaks of describing the relationship of one diameter to another.

CONCENTRICITY is not a diameter to diameter control, but an axis to axis control. The

surface condition of a part is of no concern. In reality, a part that takes the shape of a

rectangle, triangle, hexagon, etc. can be concentric to an equally irregular shaped axis.

CONCENTRICITY is an axis to axis control. It is the condition where the axis of all

cross sectional elements of a surface of revolution must fall within a cylindrical tolerance

zone whose axis coincides with the datum axis.

Must be within limit of size.

The lowest radius reading (R1) must be less than ½ the tolerance callout, and the highest radius

reading (R2) must be less than ½ the tolerance callout and both readings must fall within limits of size.

The lowest radius reading (R1) must be less than ½ the tolerance callout, and the highest radius

reading (R2) must be less than ½ the tolerance callout and both readings must fall within limits of size.

To speed up the inspection process for concentricity, check the surface of the subject feature to the

datum axis. If the indicator movement does not exceed the stated Concentricity tolerance, the

feature’s axis meets the requirement. If it does not however, rejection requires further investigation,

such as the surface condition of the elements involved.