TABLE OF CONTENTS There are many types of dimensions that are used for specific purposes in difference industries. Some may be easy to figure out, while others may require further checking. Four types of dimensions will be reviewed; reference, typical, repetitive, and THRU.
Reference dimensions are located within parenthesis (3.500), Fig. 5-11. Reference dimensions do not have tolerances and should not be used to manufacture or inspect parts. The purpose of reference dimensions is to provide additional information. The reference dimensions in Fig. 5-11 provides overall dimensions without requiring additional calculations. This information will be helpful when ordering raw material for the part. Some prints may not show reference dimensions within parenthesis and instead show REF. or REFERENCE after the dimension.
Dimensions marked TYPICAL or TYP. indicate a series of identical measurements. If a part has several measurements that are the same, it is common practice to show the dimension only once along with the word TYPICAL or TYP. Fig. 5-12. This method provides neat and easy to read instructions.
Some typical dimensions may be labeled as shown in Fig. 5-13. The PLS. stands for number of places. The dimension, .625 R. 4 PLS., indicates the .625 R. is located at four places or at the four corners.
Repetitive dimensions are similar to typical dimensions except they are labeled with an X. The X in Fig. 5-14 indicates the number of holes,...
