FACULTY OF ENGINEERING DESIGN AND PRODUCTION ENGINEERING DEPARTMENT. Credit Hour System Metrology Lab 1 MDP 240. Sine Bars. Metrology laboratory

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1 FACULTY OF ENGINEERING DESIGN AND PRODUCTION ENGINEERING DEPARTMENT Report On: Credit Hour System Metrology Lab 1 MDP 240 (13) Sine Bars Metrology laboratory Class No: B.N. Student Name Remark Signature Prepared by: Dr. Mohamed Ahmed Awad

2 Introduction: SINE BAR The high degree of precision available for linear measurement in the form of slip gauges can be utilized for the measurements of angle with the aid of a very simple but elegant piece of apparatus. The sine bar can take many forms, according to the purpose of its use and the method of application, but the simplest form is shown in the figure. Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 2

The sine bar consists of a hardened steel bar having a flat upper surface.

rollers and the length (L) can be almost indefinitely adjusted.

3 The sine bar consists of a hardened steel bar having a flat upper surface. Two equal accurate rollers are fixed to the bar either on its centre line or in locating angular grooves made for that purpose, as shown in the figure. (a) (b) (c) The form of bar shown at 'c' is usually preferred because it's easier to ensure an exact distance between the rollers and the length (L) can be almost indefinitely adjusted. Some holes are drilled in the body of the bar to reduce the weight and to facilitate handling. For the sine bar to be effective as measuring instrument, it is necessary for the essential features to be produced accurately fulfilling the following requirements: Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 3

4 a) Flatness of the upper surface. b) Equality of size and roundness of rollers. c) Exact distance between roller axes. d) Mutual parallelism between roller axes. e) Parallelism of rollers to upper surface and equality of axis distances from upper surface. The tolerances on each element should be of the order (1 to 3) m or (0.0001) inch. The following table illustrates the essential requirements for the dimensional and geometrical tolerances of sine bars: Tolerances Nominal Cylinder centre mm Inch Distance (L) * 5 10 Dimensions: Cylinder center distance 2.5 m 5 m 5x10-5 1x10-4 Cylinder diameter equality 2.5 m 2.5 m 1x10-4 1x10-4 Geometry: Upper surface flatness 1.3 m 2.5 m 1x10-4 2x10-4 Upper surface parallel to datum surface 1.3 m 2.5 m 1x10-4 2x10-4 Cylinder axes parallel and coplanar 2.5 m 2.5 m 1x10-4 1X10-4 The above tolerances values are specified by the British Standard for sine bars, B.S. 3064: Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 4

5 Sources of error: The accuracy of the angle set by a sine bar will obviously be influenced by any errors in its important dimensions. The two most obvious sources of error are: i. The distance between rollers, and ii. Errors in slip gauges used for setting. The effect of these errors will vary with the angle. Error in parallelism between the gauging surface and plane of roller axes will give a constant angular error. Effects of errors in roller centers or slip gauges can be calculated for any angle by partially differentiating the equation for the fundamental triangle of setting. For a sine bar of nominal length (L) and using slip gauges value (H), then Sin = H/L where is the angle set, and by partial differentiation. = (sec. H tan. L) / L Where is the angle error, H is the accumulated block gauge tolerance error and L is the center distance error. The shown below figure illustrates the possible effect of combined centre distance error ( L) and block gauge accumulated tolerance error ( H). Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 5

Sine bars are most frequently used as shown in case (a) as shown in the figure, but for angles greater than 45

6 The graph as well as the above equation illustrate that the measuring error in is function of sec, which increases rapidly for angle greater than 45 o. Sine bars are most frequently used as shown in case (a) as shown in the figure, but for angles greater than 45 o the bar should be set at the complement of the angle as shown in case (b) in the figure. (a) (b) Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 6

7 Uses of Sine Bar: (a) Measuring known angles or locating any work to a given angle. For this purpose the surface plate is assumed to have a perfectly flat surface, so that its surface could be treated as horizontal. One of the cylinders or rollers of sine bar is placed on the surface plate and the other roller is placed on the slip gauges height (H). Then sine = H/L, where L is the distance between the centers of the rollers and is the setting angle of the sine bar. (b) Checking unknown angles. Many a times angle of any component to be checked is unknown. In such a case, it is necessary to first find the angle approximately with the help of bevel protractor. Then, the sine bar is set at this angle and clamped to an angle plate. Next, the work is placed on the sine bar and clamped to the angle plate and a dial indicator is set at one end of the work and moved to the other and deviation is noted. Again slip gauges are so adjusted (according to this deviation) that dial indicator reads zero across the work surface. If deviation noted down by the dial indicator is ( H) over a length ( ) of the work, then height of slip gauges by which it should be adjusted is equal to H. / L. A development of the use of the sine bar is the device incorporating centers, as shown in the figure. This is a very useful device for testing the conical work centered at each end. The principle of the device setting is same as of sine bar. Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 7

accuracy. Setting is affected with the side of gauge blocks according to the sine value of the angle to be checked up to 60 o.

8 A further development of the sine bars is the sine table. It is suitable for large work of greater weight, so it is mode robust one. Taper and Wedge-Angle Tester: This device is designed for checking taper gauges, tapes, anglegauge and other work calling for maximum of accuracy. Setting is affected with the side of gauge blocks according to the sine value of the angle to be checked up to 60 o. The length of bar is equal 230 mm and the largest distance of bar from contact face is 150 mm. Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 8

9 HOW TO USE A SINE BAR / PLATE 1. To set an angle on any sine device, whether it is a sine bar, sine plate, compound sine plate, or other sine tool, you must first determine the center distance of the device (C) and the angle you wish to set (A). 2. Next, you must look up the 'setting constant' in the appropriate table. The sine tables provided in this booklet are the basic sizes needed to set an angle on most sine products. For center distances other than those sizes listed, use the appropriate multiple of the constant determined from the basic chart. For example: to obtain the constant needed to set a 15 degree 12 minute angle on a 10" sine plate, look up the constant in the 5" chart and find ". Multiply this by 2 and the result is " 3. After determining the appropriate constant, assemble a stack of gage blocks (G) equal in size to that constant. 4. Place these gage blocks under the gage block roll of the sine device, and the desired angle is set. 5. Tighten the locking mechanism on those devices that have one, and you're ready to go. Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 9

10 Main Objective: THE EXPERIMENT To study the Sine Bar, its applications and uses. Apparatus: 1. Sine Bar (10 inch); 2. Taper and Wedge-angle Tester; 3. Set of slip gauges; 4. Internal micrometer, (rod -type with exchangeable anvils); 5. Surface plate; 6. Pair of C-clamps; 7. Objects to be measured. Precautions: The following are some rules for improving the accuracy of angle measurements using Sine Bar: 1. The object to be measure is placed on a perfect flat surface plate, which could be treated as horizontal; 2. Be sure not to touch the measuring datum's of the sine bar with your bare hands; 3. Particular care must have been taken when setting the sine bar upper surface, to be coplanar, with the surface of the object; 4. Be sure not to scratch the sine bar during clamping; 5. Care of wringing and handling of slip gauges; Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 10

11 6. Be sure that the measuring anvils of the measuring tool are at right angle to the surface plate, as well as to the sine bar roller; 7. Tabulate the slip gauges used, together with their errors for each determination; 8. Reading is to be repeated at least three times for each dimension. 9. Evaluate the error of the measured angle as a function of the accumulated slip gauges tolerance error and the center distance error of sine bar. Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 11

12 Objective Study the sine bar given to You. Written the dimension of the sine bar as well as the dimensional and geometrical tolerances of it. Instruct the uses of the Sine bar. Shape and dimensions Tolerances of Sine bar Cylinder center distance Cylinder diameter equality Dimensions Geometry Upper surface flatness Upper surface parallism to datum surface Cylinder axis parallel and coplanar Uses Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 12

13 Objective Measure the angle of the given product using Sine bar given to you. Use slip gauges t measure the difference in the level of the bar rollers. Calculate the error in the measured angle. Note: measurement are to be repeated at least three times for each parameter. Sketch of the Object Items H1 H2 Readings Angle Readings Bar length (L) Average Center distance error (δl) Accumulated slip gauge tolerance error (δh) Results θ=sin -1 { H1-H2)/L} θδ={sec θ δh tan θ δl}/l Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 13

14 Objective Study the construction and the basic elements of the taper and wedge angle tester. Write the specifications of the given tester and the fields of its uses. 1- Construction & Basic Elements 2- Specifications Cylinder diameter Cylinder center distance Scale value of the protractor Measuring range of protractor Largest distance of bar form center face 3- Uses Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 14

15 Objective Draw sketches to show the different methods of measuring angle with the taper and Wedge angle tester. Measure the angle of the given plug using the angle tester. Use micrometer to measure the difference in level of the two rollers of the sine bar. Compare between the results obtained by the two methods. Sketch of measuring method Items H1 H2 Readings Angle Readings Bar length = Average Protractor reading Results θ =sin -1 { H1-H2)/L} Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 15

16 Comparison & Discussion Conclusions Credit hour System Metrology Lab 1 -MDP 240 Prepared by Dr. Mohamed Ahmed AwadPage 16

FACULTY OF ENGINEERING DESIGN AND PRODUCTION ENGINEERING DEPARTMENT. Credit Hour System Metrology Lab 1 MDP 240 (1) Fixed gauges. Metrology laboratory

FACULTY OF ENGINEERING DESIGN AND PRODUCTION ENGINEERING DEPARTMENT Report On: Credit Hour System Metrology Lab 1 MDP 240 (1) Fixed gauges Metrology laboratory Class No: B.N. Student Name Remark Signature