Combi ya sine bar na vernier PDF

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lab report...

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DATA ANALYSIS STEEL RULE AND VERNIER CALLIPER The calculations obtained were as follows: Steel rule width average:

6 +6.2 + 6 3

= 6.07 mm

height average:

6 +6.2 + 6 3

= 6.07 mm

length average:

48 + 48 + 48 3

= 48.0 mm

Volume = length x width x height = (6.07 x 6.07 x 48) = 1768.555

mm

mm

3

3

Vernier caliper width average:

6 +6.2 + 6.2 3

= 6.13 mm

height average:

6 +6.2 + 6.2 3

= 6.13 mm

length average:

47.8 + 47.2 + 48 3

= 47.67 mm

Volume = length x width x height = (6.13 x 6.13 x 47.67) = 1773.76

mm

mm

3

3

Volume difference (1773.76 – 1768.555) = 5.21

m m3

1cm =10 mm 1 c m3 = 10 00 mm 3

1 c m3 x 5.21 m m3 3 10 00 m m

=

−3 3 = 5.21 x 1 0 c m

Reproducibility for the steelrule

i−¿ x¯ x¿ ¿ Σ¿ s2 =¿ Width 2

s=

(6−6.07 ) ² (6.2−6.07 ) ² (6−6.07 ) ² + + =0.01335 mm ² 3−1 3−1 3−1 S= 0.1155 mm ² height

2

s=

(6−6.07 ) ² (6.2−6.07 ) ² (6−6.07 ) ² =0.01335 mm ² + + 3−1 3−1 3−1 S= 0.1155 mm ² Length

s 2=

(48− 48 )² (48− 48 )² (48− 48 ) ² + + =0 mm ² 3−1 3−1 3−1 S= 0 mm ²

Reproducibility for the vernier caliper i−¿ x¯ x¿ ¿ Σ¿ s2 =¿ Width 2

s=

(6−6.13 ) ² (6.2−6.13 ) ² (6.2−6.13 ) ² + + =0.01335 mm ² 3−1 3−1 3−1

S= 0.1155 mm ² height s 2=

(6−6.07 ) ² (6.2−6.07 ) ² (6−6.07 ) ² =00.01335 mm ² + + 3−1 3−1 3−1 S= 0.1155 mm ²

Length 2

s=

(47.8−47.67 )² (47.2− 47.67 )² (48− 47.67 ) ² =0.17335 mm ² + + 3−1 3−1 3−1 S= 0 .4164 mm ²

SINE BAR The working principle of the sine bar is the trigonometric function which is usually obtained by sin = side opposite angle/hypotenuse. Top Flat Surface Steel Beam

h d

L

Rolle

Figure 1: Sine Bar Sine Bar

L

h θ

Gauge Blocks

h

Figure 2: Use of Sine Bar for Angle Measurement

Experimental angle

sin θ =

h l

θ =

h l ¿ sin−1 ¿

θ =

103.5 20 = 31.2 º ¿ −1 sin ¿

Actual angle measured by the bevel protractor was found to be 34 º Difference between the actual angle and the theoretical angle was 34 º - 31.16 º = 2.84 º

DISCUSION STEEL RULE AND VERNIER CALIPER During measurement of a rectangular metal block, the steel rule and the vernier caliper were used to measure width, length and height. The precisions of these instruments vary hence giving different measurements of the same object. The precision of the steel rule is 0.1cm while that of the vernier caliper is 0.01 thus enabling us to identify that the vernier caliper was more accurate than the steel rule. The volume calculated from the values obtained from measurements by vernier caliper was higher than that obtained from the steel rule by 0.00521cm3 . values differed due to errors that occurred such as parallax error while taking readings from the vernier caliper and steel rule.

SINE BAR AND GAUGE BLOCKS Measurements were done with an objective of demonstrating the use of gauge blocks to measure the taper angle of the triangular test piece by setting the sine bar at a given angle. The dial indicator was used in checking whether the length of the triangular test piece was perfectly horizontal with the surfaced plate or not. Trials were made with different sizes of gauge blocks that were being placed making the sine bar to slant at an angle. The triangular test piece was placed on top of the sine bar in that when the inclination angle of the sine bar changes the dial indicator was used to check whether the length of the triangular piece was horizontal. The number of gauge blocks used to bring the length of the triangular test piece horizontal were found to be two of dimension 100mm and 3.5mm. The height of the side opposite the inclination angle was found to be 103.5mm and the angle obtained by the sin trigonometric relationship and found to be 31.2⁰ . Least number of gauge

blocks were needed so as to reduce the amount of uncertainty in measurement. The taper angle of a triangular test piece of unknown hypotenuse, length and base was found by using bevel protractor and the angle obtained was found to be 34⁰ . The difference in the angle is due to errors that occurred such as parallax error during reading angle on the protractor, the surface plate not being cleaned hence not perfectly flat, some instruments not being in good conditions for use. CONCLUSION The principle of operation of Vernier caliper is such that the smallest graduation on the main scale is divided into equal number of parts on the sliding scale The findings in sine bar experiment lead to the conclusion that two blocks of dimension 100mm and 3.5mm are the least number of blocks used to give the ideal length of the triangular test piece. The taper angle found by the use of sine bar and gauge blocks was 31.2⁰ .

RECOMMENDATIONS (a)

All the instruments should be cleaned properly.

(b)

Any burrs and damage on workpiece surfaces should be rectified.

(c)

The institution should equip students with equipment that are in good condition for usage.

REFERENCES https://www.researchgate.net/publication/319648634_Metrology _laboratory. CONNIE L. DOTSO Fundamentals of Dimensional Metrology ANAND K BEWOOR, VINAY A KULKARNI (2009) Metrology & Measurement...