JNTU Previous papers B-Tech-Metro logy- Supplementary Examinations-Aug/Sep 2008

JNTU B.Tech Supplementary Examinations, Aug/Sep 2008


(Mechanical Engineering)


1. (a) Explain the terms: Basic size; Zero line; lower and upper deviations. Draw a conventional diagram to represent these terms for a shaft and hole pair of interference fit.

(b) The hole and shaft assembly of 30mm nominal size have tolerances specified

as 30+0.02?0.000mm for hole and 30?0.04?0.07mm for shaft. Determine

i. Maximum and minimum clearance (interference) attainable

ii. Allowance

iii. Hole and shaft tolerances

iv. Fundamental deviation

v. MML for shaft and hole

vi. Type of fit.

Sketch these values on a conventional diagram.


2. (a) Describe the selection of minimum number of slip gauges for a dimension of 29.759mm from M112 set. What care of slip gauges is essential ?

(b) Describe the working principle and uses of Lever type dial test indicator.


3. Discuss various methods of taper measurement of plug and ring gauges.


4. (a) Differentiate between limit plug gangue and ring gauge.

(b) Design general type GO and NO-GO gauges for components having 75 H9/d10 fit. The basic size falls in the diameter range of 50-80mm. The fundamental deviation for ‘d’ shaft=(-16 D0.41) microns. The multipliers for 9 and 10 grades are 40 and 63. Take wear allowance as 10% of gauge tolerance. Sketch the gauges with values.


5. Describe the working principle of NPL Flatness interferometer with a sketch. What are the fringe patterns obtainable in case of tapered surfaces.


6. (a) Enumerate various direct instrument methods for measurement of surface finish.

(b) Describe surface measurement with inspection by comparison methods.


7. (a) What are the advantages and disadvantages of mechanical comparators.

(b) Explain the working principle of mechanical-optical comparator.


8. (a) Elucidate the Effective diameter measurement by two wire method

(b) Explicate gear metrology of spur gears with reference to

i. Lead

ii. pitch

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