The minimum depth of thread engagement for a 1/2 inch eyebolt into steel is 3/4 inch.

• A. 1/4 in
• B. 3/4 in
• C. 1 in
• D. 1 1/4 in

Answer: (B)

The key idea is that threaded engagement length determines how load is shared between the bolt and the base material. For steel-to-steel connections, a practical rule of thumb is to have about 1.5 times the bolt diameter of engagement so the bolt threads, not just the shank, carry the load. For a half-inch eyebolt, that works out to 0.75 inches of threaded engagement. Engaging at least this much helps prevent thread stripping and ensures the bolt yields or the surrounding material fails in a controlled way, giving a safer, reliable connection. If the engagement were much shorter, the force would concentrate on fewer threads and the joint could fail sooner.