Before changing spindle directions on a lathe, what is required?

• A. Let the machine come to a stop
• B. Immediately reverse direction
• C. Increase speed first
• D. Deburr the workpiece

Answer: (A)

Letting the spindle come to a complete stop before changing direction is essential for safety and protecting the machine. When the spindle, chuck, and tool are rotating, reversing the drive can create a sudden shock as inertia fights the change, which can cause the tool to dig in, the workpiece to move, or gear and bearing damage. Wait for the brake to stop the motion and confirm the spindle is at rest before selecting the opposite direction, so energy and momentum are fully dissipated. The other options don’t address this risk: reversing immediately while spinning is hazardous, increasing speed first serves no safe purpose, and deburring the workpiece is unrelated to how you change the spindle’s direction.