What component in a horizontal milling machine holds and rotates the milling cutter?

The component in a horizontal milling machine that holds and rotates the milling cutter is the spindle. The spindle serves as the primary mechanism that secures the cutter in place and provides the necessary rotational motion to perform milling operations. It is an integral part of the machine that can be adjusted to different speeds depending on the material being machined and the specific requirements of the operation.

The drive shaft is responsible for transferring power from the motor to the spindle but does not hold or directly rotate the cutter itself. The arbor, while it may be used to hold the cutter, is typically a separate attachment that can be mounted to the spindle. The base, on the other hand, is the foundational structure of the milling machine that supports all other components but does not function to rotate the cutter. Therefore, the spindle is the correct choice as it specifically fulfills the role of holding and rotating the milling cutter in a horizontal milling machine.