Answer :
Final answer:
b) Dial indicator and test bar are the preferred methods for approximate alignment when turning work between centers.
Explanation:
When turning work between centers, it is crucial to ensure proper alignment to avoid the creation of tapered pieces. The two methods for approximate alignment are the use of a dial indicator and a test bar.
A dial indicator is employed to measure any misalignment between the centers. It consists of a sensitive needle that moves in response to deviations from the axis of rotation. By carefully observing the dial indicator readings as the work is turned, one can gauge the alignment and make necessary adjustments.
In conjunction with the dial indicator, a test bar is employed to verify and fine-tune the alignment. The test bar is a precision ground bar inserted between the centers, allowing for a more accurate assessment of alignment. The deviation from parallelism can be measured using the dial indicator, and adjustments can be made accordingly.
These methods provide a systematic approach to ensuring the proper alignment of centers, minimizing the risk of tapered pieces during turning operations. It is essential to maintain precision in machining processes to achieve desired results consistently.
therefore, tye correct answer is b) Dial indicator and test bar
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