Reading an Architectural scale Ruler
It is not as difficult as it first appears.
Keep in mind, We are Cabinetmakers and not Carpenters, So the breakdown is of a foot, in 12ths (inches) and not 16ths or 32nds like a regular tape measure.
Thats ok
Because on a drawing, the fragments of an inch are too small to decipher.
Because 3" fits into 12" (one foot 1' ) four times, 3" = 1'-0"
On plans, It is often written as a ratio of
1 : 4
1 1/2" = 1'
or
1.5 / 12
so the Ratio is 1:8
The unit of 12" (1') is shrunk down to the unit of 1 1/2" (1.5")
However as you can see, if the unit of measure is changed from 1' to 1", the ruler can be used to draw in 1/2 scale (1:2) or 1/4 scale (1:4) and so on..
In Metric, The scale is only represented as a ratio, because there are no fractions
Find the scale on a drawing in class
