BNG 101 – Engineering Graphics

Slide Set 6 – Dimensioning II

Drawing scale and dimensioning

Drawing scale is noted in title block Older drawings may indicate “NTS”; when using CAD, take the time to correct the geometry to reflect changes

Drawing scale and dimensioning

• Keep dimensioning and lettering at small scales

Are reduced size working prints going to be used? May increase lettering size, dimensioning arrows, etc. by 50%

Direction of dimension values and notes

Dimension values and notes should be lettered horizontally

Exception: Coordinate dimensioning

Decimal and mm equivalents

In title block: “All measurements in mm unless otherwise noted” or “All measurements in inches unless otherwise noted”

Millimeter dimensioning example

Decimal inch dimensioning example

How many significant digits?

It is difficult to maintain tolerances smaller than a few thousands of an inch!

Example 0.001’’ is how many millimeters? __________________________ Generally, round to (at most) two digits to the right of the decimal point

Dual dimensioning

Dimension symbols

Dimension symbols – example

Rules for placing dimensions properly

Rules for placing dimensions properly

Rules for placing dimensions properly

Rules for placing dimensions properly

Exercise: which view is clearer and why?