Lapjoint

A lap joint, or lapped joint, is a method of joining two workpieces by overlapping them and fastening or bonding along the overlapped region. It is widely used in metalworking and woodworking because it provides a simple, inexpensive way to connect parts with minimal preparation and specialized tooling.

In metalworking, lap joints are typically formed by overlapping two plates and securing them with rivets, bolts, welds, or adhesives. The most common forms are the single-lap joint, where one piece overlaps the other at a single location, and the double-lap joint, where both pieces overlap on both sides of the joint. In sheet metal and aircraft construction, lap joints can offer a practical means of joining skins and structural members.

In woodworking, a half-lap joint is produced by removing half the thickness from each piece at the joint, allowing the pieces to sit flush and form a strong right-angle connection. A full or full-depth lap uses the full thickness of the pieces for greater contact area and strength, though it can require more precise cutting and greater material removal.

Construction and load paths: In a single-lap joint, load is carried mainly by the overlapped members and fasteners, which can introduce bending moments and shear stresses that may cause wear or distortion. Double-lap joints distribute the load more evenly and can improve stiffness, at the cost of additional material and fabrication steps.

Advantages and limitations: Lap joints are quick to fabricate, tolerant of minor misalignment, and suitable where full joints are impractical. Their strength depends on overlap length, material properties, and the fastening method; they may be less stiff or strong in tension than some alternative joints unless reinforced.

Applications: common in frame construction, furniture assembly, sheet-metal fabrications, and repair work where a simple and accessible joint is advantageous.