How to reduce vibration when cutting thread on the lathe?

Here are a few possible solutions to lowering the vibration or chatter when cutting threads on a lathe:

• If possible, grip the workpiece deeper into the chuck
• Shorten the protruding tail stock quill and lock the tail stock lever
• Lower the cutting speed or in some cases increase it
• Ensure the tool is sharp
• Make sure the tool tip is not above the center line or too far below it
• Use cutting oil

The following items are free cutting angle should not exceed the limit.

Eighth-grade steel.