Millwright Level 1 Practice Exam

What mechanism draws the arbor or collet chuck into the spindle of the milling machine?

1. The draw bolt

2. The spindle lock

3. The power feed mechanism

4. The locking collar

The correct answer is: The draw bolt

The mechanism that draws the arbor or collet chuck into the spindle of a milling machine is the draw bolt. The draw bolt is a critical component that allows the operator to securely grip the cutting tool, such as an end mill, within the spindle. When the draw bolt is tightened, it pulls the arbor or collet into the spindle taper, ensuring a firm connection that can withstand the forces generated during machining operations. The draw bolt is essential for maintaining tool stability and accuracy during cutting processes. A well-secured tool minimizes vibration and helps achieve precision in the machining task. The functionality of the draw bolt is crucial when changing tools, as it allows for quick and efficient tool changes while ensuring the tools are properly and safely mounted for operation. In contrast, the spindle lock is used to immobilize the spindle for tool changes but does not act to pull the arbor in. The power feed mechanism is related to moving the workpiece or the cutting tool, and the locking collar typically serves to lock or secure components in place rather than drawing them into the spindle. Each of these other components plays a role in the milling operation but does not perform the specific function of drawing the arbor into the spindle as the draw bolt does.