Page 62 - ENGINEERING DRAWING

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Plus and minus The allowable positive and negative variance from the dimension
-
dimensioning specified

The largest acceptable size (maximum material condition) and
Limits and size - the minimum (minimum material condition) acceptable size of a
feature
the symbol which is placed preceding a numerical value indicating
Diameter
- that the associated dimension shows the diameter of a circle. The
symbol
used is the Greek letter Ø
the symbol which is placed preceding a numerical value indicating
Radius symbol - that the associated dimension shows the radius of a circle. The

radius symbol used is the capital letter R
the theoretically exact point used as a reference for tabular
Datum -
dimensioning

4.4 Basic Concept

Size dimension might be
the overall width of the

part or the diameter of a

drilled hole.

• Horizontal
• Vertical
• Diameter
• Radius

Location dimension might

be the length from the

edge of the object to the
centre of the drilled hole.

• Horizontal
• Vertical
• Angle

Figure 4.8 : Size and location dimension