The formula to calculate the clearance hole (CH) is:
\[ CH = \frac{DF + DH}{2} \]
Where:
A clearance hole is the hole that allows a fastener to pass through without threading into the material. It is calculated based on the diameters of the fastener and its head.
For example, if the diameter of the fastener (DF) is 0.5 inches and the diameter of the fastener head (DH) is 0.75 inches, the clearance hole (CH) can be calculated as follows:
\[ CH = \frac{0.5 + 0.75}{2} = \frac{1.25}{2} = 0.625 \text{ inches} \]
So, the clearance hole for these values is 0.625 inches.