Threading & Tapping

Articles • December 1, 1997 • William Sluhan

Itching for a Solution

This article reviews the causes of skin irritation suffered by some shop workers, with special attention paid to skin conditions that result from poorly maintained metalcutting fluids. The article also discusses the factors that can aggravate skin problems and suggests ways that workers can protect themselves from skin irritants.

Articles • September 1, 1997 • David Miskinis

Know What You’re Tapping

Traditional tap/drill charts recommend drill diameters for each size of tapped hole. But, according to this article, these recommendations are based on the size holes that were typically produced by less-accurate tools and processes used in the past. This article suggests guidelines for producing holes that will, in turn, produce correctly sized tapped holes.

Articles • February 1, 1997 • Tom Lingafelter

The Need for Feed Units

There are several types of feed units for drilling and tapping on the market, varying in capability and the type of drive. This article discusses the difference between units and suggests questions users should ask themselves before selecting a unit. Factors to be considered include the volume of production, cost engineering and tool requirements.

Articles • August 1, 1996 • Peter Zierhut

New Twists on Threading

The advent of CNCs made new threadmaking technologies practical. Among these technologies are rigid tapping and thread milling. This article describes the uses, techniques and benefits of these two threadmaking methods.

Articles • August 1, 1996 • Allen Krenick

Rigid Rules

There are some tapping situations that call for a rigid tapholder and some that call for a length-compensating holder. Often the choice depends on the capabilities of the machine and the CNC driving the tap. This article discusses why a machinist might choose one type of tapholder or the other.

Articles • August 1, 1996 • John Edmond

The Good, the Bad and the Retapped

Internal threads can end up undersized because of the work material's properties or because of changes to the hole's dimensions caused by plating or heat-treating processes performed after tapping. This article explains H- and D-limits and how to use them to specify a tap that will produce the right size thread, regardless of any post-tapping operations.

Articles • August 1, 1995 • Al McBride

Thread Rolling on CNC?

Thread rolling produces OD threads by cold profiling the thread form onto the workpiece rather than cutting. According to this article, this yields significant benefits over using single-point tools to cut threads. The article also discusses the different types of thread-rolling units and their uses on modern machine tools.

Articles • August 1, 1995 • Doug Moore

Driving the Tap

The choice of tapping driver, the component between the spindle and the tap, can affect the quality and accuracy of the threads as well as the rate of wear on the tap and the machine tool. This article discusses how features such as length compensation and self-reversing protect against damage caused by machine and tool errors.

Articles • August 1, 1995 • Dan Gajdosik

Threads Will Roll

Roll-forming taps produce internal threads by displacing the metal under pressure rather than cutting it. This article explains how to perform the operation to achieve good quality threads. Formulas and charts help the user calculate the proper size hole and the size of tap to use for a desired thread.

Articles • August 1, 1995 • Lee Carroll

Tapping the Deep Hole

Tapping holes 1 1/2 times the tap diameter or deeper requires greater care than other tap operations. This article discusses the chip evacuation problems that can make deep-hole tapping a challenge and the tap geometries and flute designs that can tap these holes successfully.