Each Self-Locking Tap Extension is precision machined from high quality tool steel and guaranteed against defects in material or workmanship. The secret of the Tap Extensions’ self-locking design is a precision machined EDM cavity that receives the end of a standard tap. The bottom part of the cavity is a tapered square with a wall angle of less than one degree, which receives the square section of the tap and grips it so securely that a thin drift is needed to separate the tap and the extension. The cylindrical part of the tap shank fits tightly into a similar cavity in the extension providing resistance to bending. Each extension is designed for a specific tap size, and the tapered square and round socket conform to the size standards of leading tap manufacturers.

Because the Tap Extension has no set screws or collars which extend shaft diameter, and because each extension is sized for a particular tap size, it offers unique capabilities in allowing the user to tap close to the edge or shoulder of the workpiece. With the Tap Extension, as opposed to collar types, the distance from centerline to the edge of the workpiece can be as little as one half the diameter of the extension size.