Class Presentations-Linear n angular measuring.

Vernier calipers
Micrometers
Slip gauge or gauge blocks
Comparators

1. Linear and Angular measuring instruments

2. Linear measuring instruments Vernier calipers Micrometers Slip gauge or gauge blocks Comparators

3. Interval Measurements Slip Gauges- made of hardened alloy steel of rectangular cross-section. surfaces of made to a high degree of accuracy all slip gauges are made to same thickness to perform wringing Wringing or Sliding -combining the faces of slip gauges one over the other . Adhesion property of slip gauges, causes them to stick together.

4. Principle of Laser Interferometry Two light rays from the same monochromatic light source combined. Brightness varied by changing phase difference btn them Brightness is a measure of displacement. Bright- Constructive interference- phase angle=0 Dark- Destructive intereference -phase angle=180

5. INTERFEROMETER Instrument used to compare the unknown length with number of known wavelengths of light . Rays from a monochromatic light source collimated into parallel rays by a lens Mirror A is partially silvered. Half reflected to mirror B Half passes thro work-piece n table. Light then reflected back to mirror A

6. Interferometer cont … Some light from B passes through the partially silvered surface towards the eye some light from the work-piece and table surfaces also reflected to eye. If the paths of these two are separated and then reunited , light rays become equal in length, constructive interference, the work-piece and table surface appear to be ordinarily illuminated. If the path of the light reflected from the work-piece surface differs in length from that of the light reflected from mirror B by one half wavelength , the work-piece appears dark . If the table is slightly tilted by a small angle, a series of interference bands appear

7. Assignment 1 Briefly describe the working principle of the following instruments. AC Laser Interferometer Michelson Interferometer Dual Frequency Laser Interferometer Twyman -Green Interferometer Optical flat How can a laser interferometer be used to measure angles?

8. Angular Measurements Sine bar Bevel protractor Vernier bevel protractor Universal protractor Optical protractor Autocollimator Angle Dekkor

9. Taper Measurements Angle gauges Rollers Angle gauges Angle gauges are supplied in sets and can be wrung together to form desired angles . Supplied in set of thirteen pieces in one box including a square block They make an angle 0-360 degrees

10. For example, measure the angle 43°24'12 ", given the gauges available are. SOLUTION

11. Rollers Determines linear and angular dimensions in conjunction with gauge blocks Made of Good quality steel and are hardened and tapered length of the roller is equal to the diameter . How to measure angles:

12. Read on: How rollers can be used to Check the angle of taper plug. Measuring of included angle of an internal dovetail Measure the interior angle of a profile gauge Measure the angle of a tapered hole Measure the taper angle of a shallow circular groove Measure the angle of a transverse recess having small tapered angle Measure an internal taper in blind hole