Lathe operations: Which method is most suitable for turning an internal taper (inside a hole) on a lathe?

Introduction / Context:
Internal tapers are common in machine components such as sockets, valve seats, and Morse taper holes. Unlike external tapers, internal tapers are generated with a boring tool working inside a pre-drilled or rough-bored hole. This question checks your understanding of practical lathe methods suitable for producing an accurate internal taper.

Given Data / Assumptions:

• Work is mounted on a lathe and a hole exists to be tapered internally.
• A standard single-point boring tool can be used.
• We seek a general, widely used method on conventional lathes.

Concept / Approach:
For internal tapers, the most straightforward and controllable method on a conventional engine lathe is to swivel (index) the compound rest to the desired half-angle of the taper and feed the boring tool using the compound slide. This provides precise angular control and is ideal for short to medium-length internal tapers. Other methods either do not apply to internal geometry or are less convenient for typical jobs.

Step-by-Step Solution:

Verification / Alternative check:
If available, a taper attachment can generate tapers accurately; however, it is more frequently used for external tapers. For many shops, the compound-rest method remains the default for internal tapers due to simplicity and control.

Why Other Options Are Wrong:

• Form tool: rarely used internally; chip evacuation and interference are problematic except for very short, shallow tapers.
• Setting over the tailstock: suited to external tapers between centers, not internal tapers.
• Taper turning attachment: mainly for external tapers; internal use is uncommon and setup is more complex.
• Offsetting the headstock: not a standard method for producing accurate tapers.

Common Pitfalls:
Insufficient boring bar rigidity causing chatter; incorrect compound angle (use half-angle); inadequate relief on the boring tool leading to rubbing and poor finish.

Final Answer:
by swivelling the compound rest