What is the purpose of tapping the top of the drawbar with a dead blow hammer?

Tapping the top of the drawbar with a dead blow hammer serves the primary purpose of loosening the taper of the tool that is held in the spindle. When a tool, such as a collet or end mill, is inserted into the spindle, it typically engages through a taper fit. Over time, especially after the tool has been in use for an extended period, this taper can become tight due to friction and the forces exerted during machining operations.

Using a dead blow hammer is advantageous because it delivers a forceful yet controlled impact without damaging the drawbar or the tool itself. This gentle tapping helps to break the bond created by the taper, allowing the tool to be easily removed from the spindle without excessive force that might cause damage to the machine or tooling components.

Securing the table, tightening the collet, or adjusting the knee do not directly relate to the task of tapping the drawbar. Each of those functions focuses on different aspects of machine operation unrelated to the tool release mechanism. Thus, the action of tapping the drawbar specifically targets the loosening of the taper, making it the most appropriate answer.