On a protruding head lockbolt, grip length is measured from the bottom of the head to which part of the shank?

The grip length of a protruding head lockbolt is defined as the measurement from the bottom of the head of the bolt down to the end of the shank. This measurement is crucial because it helps determine the overall length of engagement that the bolt will have within the structure it is fastening. Proper grip length ensures that the fastener is appropriately sized for the material thickness being joined, providing sufficient strength and structural integrity.

When selecting a lockbolt, knowing the accurate grip length is essential for achieving the correct clamping force and preventing joint failure, which may occur if the grip length is too short or too long. Overall, focusing on the end of the shank as the reference point allows for accurate and consistent measurements critical for effective aerospace assembly operations.