Intro to Millwright Practice Exam

Which of the following is NOT used for tapping a blind hole?

1. Taper Tap

2. Plug Tap

3. Bottom Tap

4. Drift Tap

The correct answer is: Drift Tap

A drift tap is not used for tapping a blind hole because it is specifically designed for applications that require the tapping process to allow for clearance, such as in through holes or where the tap must be removed easily after cutting the threads. Drift taps are typically utilized in situations where the threads will not be relieved or when alignment is necessary, making them inappropriate for blind holes, which have limited space at the bottom. In contrast, the taper tap, plug tap, and bottom tap are all suitable for blind holes. Taper taps start the threading process and are tapered on the leading edge to help guide them into the hole, making them ideal for initial engagement in blind holes. Plug taps have a less tapered lead than taper taps, allowing them to create deeper threads in a blind hole, while bottom taps are designed specifically to cut threads all the way to the bottom of such holes, where no further tapping can happen. These various taps serve specific functions that accommodate the unique aspects of blind holes, ensuring a variety of applications in threads creation.