The root length of a bolt is the length of the bolt measured at the root diameter, which is the diameter at the bottom of the threads. This measurement is important for understanding the bolt's strength and load-bearing capacity.
The formula to calculate the root diameter is:
\[ D_r = D - 1.226869 \times P \]
Where \( D \) is the nominal diameter and \( P \) is the thread pitch.
Consider a bolt with the following details:
Using the formula:
\[ D_r = 12 - 1.226869 \times 1.75 = 9.854 \, \text{mm} \]