1. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

2. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Introduction
The sine bar is the most accurate instrument for measuring angles.
It consists of a accurate straight rectangular bar made of high quality steel and having two accurately lapped cylindrical plugs or rollers at the ends.
The rollers are so fixed that when sine bar is placed on surface plate, the surface of the bar is exactly parallel to surface plate.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

3. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Types
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

4. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

5. Principle of Working of Sine Bar:
By placing the slip gauges under the one roller, the bar surface can be made parallel to any angular surface of work.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

6. Measuring known angles
For this purpose the surface plate is assumed to be having 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 other roller is placed on the slip gauges of height h.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

7. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

8. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

9. Measurement of Angle for Small Component:
For checking the angle of small size components, a sine bar is set up approximate (Nominal) angle on a surface plate by suitable combination of slip gauges.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

10. Measurement of Angle for Large Component:
When component is too large to be mounted on the sin-bar, the sine bar can be mounted on the component.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

11. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Sine Bars
Used on surface plates and any angle by raising one end of bar with gage blocks
Made 5 in. or in multiples of 5 in.
Lapped cylinders with 5 in. ± or 10 in. ± between centers
Face accurate to within in. in 5 inches
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

12. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Activity
Run to the Board
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

13. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Sine Bars
Hypotenuse of a right-angle triangle
Gage block buildup forms side opposite
Face of surface plate forms side adjacent
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

14. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Example
Calculate the gage block buildup required to set
a 5 in. sine bar to an angle of 30º
buildup = 5 (sin 30º)
= 5(.5000)
= in.
Note: This formula applied only to angles up to 60º .
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

15. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Sine Bars
Angles > 60º
Better to set up work using complement of angle
Angle plate turned 90º to produce correct angle
When sine bar in near-horizontal position, small change in height of buildup will produce smaller change in angle than near-vertical position
Small angles
Sometimes impossible to get buildup small enough to place under one end of sine bar
Place gage blocks under both rolls of sine bar
Net difference in measurement equal to required buildup
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

16. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Sine Centre
Conical workpiece difficult to mount so Sine centre is used.
Centre can be adjusted.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH

17. Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH
Sine Table
One roller of the sine bar is hinged on its datum surface
It can be sung at any angle from 0 to 90 degree.
Measuring Angles of Taper Plug Gauge.
Unit-2 , M&M, Sine Bar , B SUSILA AP/MECH