Category Archive: tapping and countersinking

The Uses of Tapping and Countersinking

While a CNC machine can handle a wide range of cutting, sometimes manual tapping and countersinking are needed to add finishing touches to a machine part. Tapping involves cutting threads on the inside surface of a hole. Countersinking means cutting a conical hole into metal, usually to allow space for a screw or bolt. Sometimes the project calls for customization so that a human must assist the automation. Both tapping and countersinking add subtleties to functions and designs of screws.

Precision Tapping

Tapping must be done with precision so that the hole works properly as a fastener. The manual tool that achieves this goal is called a tap, which can also be used for cutting threads on the inner surface of nuts. Tapping can also be done on a tapping or milling machine or a lathe. While a tap or equivalent is used to create the female portion of the fastener, a die is used for making the male part, such as a screw. The die, which comes in various shapes and sizes, can cut a thread on round tubes. The work piece is typically smaller than the diameter of the die.

The operator, working at a tapping station, must align the tap with the hole properly to avoid angular errors that may result in breaking the tap. The direction the nut will move is established with the cut of the first few threads. Various lubricants may be used during the tapping the process for smoother operation.

Countersinking and Its Benefits

One of the main reasons to use countersinking is to prevent corrosion by allowing for a tight seal. It’s useful for long-term installations, such as underground piping, boosting the quality of both workmanship and installation. A countersink expands the diameter, allowing for a screw head to make a more secure connection. It can be applied to sheet metal fabrication for the manufacturing of any fastening device for any existing hole.

Boring a larger hole allows for the fastener to fit snug in the hole. The covered screw is protected and has a longer life span than an exposed screw. Another advantage to countersinking is that it can prevent sharp edges from extending and causing damage. The wider hole used in the countersinking technique reduces sharpness. Dimpling is similar to countersinking in the sense that conical holes are arranged in rows and columns of sheet metal. This method allows for easy stacking and transportation of sheet metal.


Tapping and countersinking are helpful additional processes for customizing machine fasteners to create more stable solutions. Contact Serra Laser for answers to your questions about using the most efficient solutions for metal fabrication.