Experiment No. 1 Demonstration of linear and angular measuring instruments, slip gauges and their applications.

EXPERIMENT NO: - 01

Aim:- Demonstration of linear and angular measuring instruments, slip gauges and their applications.

Apparatus :-Vernier Caliper, Vernier Height Gauge, Micrometer, And Measuring Parts

Vernier Height Gauge

This is just as vernier caliper, equipped with special base block and other attachment which make the instrument suitable for height measurements. Along with the sliding jaw assembly, arrangement is provided to carry a removable clamp. The upper and lower surfaces of the measuring jaws are parallel to the base, so that it can be used for measurements over or under surface. The vernier height gauge is mainly used in the inspection of parts and work. With a scribing attachment in place of measuring jow, this can be used to scribe lines at certain distance above the surface. However dial indicator Can also be attached in the clamp and many useful measurements made as it exactly  gives indication when dial tip just touching surface. For all these measurement, use of surface plate as datum surface is very essential.

 

PROCEDURE-

1. Take the material (sample) for which the value must be measured.
2. Check the vernier and main scale must coincide at 0
3. After checking the 0 mark put the sample piece and slowly leaves the measuring jaw
over the piece
4. Tight the screw and measure the main scale also vernier scale reading
5. The line coincide with the main scale that the VSR
6. By adding MSR with VSR*L
DIAGRAM OF VERNIER HEIGHT GAUGE

[1]

 Please see the video animation for working of vernier height gauge and their least count.

OBSERVATION TABLE FOR VERNIER HEIGHT GAUGE

VERNIER INSTRUMENTS:-

The three elements of venire caliper, viz. beam, fixed jaw, and sliding jaw permit substantial improvements in the commonly used measuring techniques over direct measurement with line graduated rules. The alignment of the distance boundaries with  the graduations of the rule is ensured by means of the positive contact member

DIAGRAM OF VERNIER CALIPER

[2]

Please see the video for calculation of Least count of vernier caliper

Use of vernier caliper and micrometer for Linear measurement

OBSERVATION TABLE FOR VERNIER GAUGE

   

MICROMETER

The end of the screw forms one measuring tip and the other measuring tip is constituted by a stationary anvil in the base of the frame. The screw is threaded for  certain length and is plan afterwards. The plain portion is called sleeve and its end is the measuring surface. The spindle is advanced by turning thimble connected to the spindle. The spindle is aside fit over the barre land barrel is the fixed part attached with frame.  The barrel is graduated in unit of 0.05 cm. i.e.20 division per cm, which is the lead of the screw for one complete revolution. The thimble has got 25 divisions around its periphery on circular portion. Thus it sub-divides each revolution of the screw in 25 equal parts; i.e.each division corresponds to 0.02 cm.

Please see the video for micrometer least count calculation

PROCEDURE
1. The whole movable jaw assembly is adjusted so that the two measuring tip just touch
two parts to be measured.
2. Then lock nut is tightened.
3.  Final  adjustment  depending  upon  the  sense  of  correct  feel is  made  by  the  adjusting
screw.
4. Measuer the main scale readings i.e. the line coincide with o mark of vernier scale and
noted down the reading.
5. The measuring tip is so designed as to measure inside as well as outside dimension.
6. Calculate MSR, VSR and TSR

DIAGRAM OF SCREW GAUGE:

[3]

PROCEDURE
1. Take sample piece and slowly move the screw in clockwise direction and clock the nut
2. Now measure the circular part and line coinciding withthe scale.
3.  Calculate  MSR,  VSR  and  TSR.   Take  down  the  reading  and  follow  the  same
procedure.
OBSERVATION TABLE

    
MICROMETER DEPTH GAUGE

It is used for measuring the depth of holes, slots and recessed areas. It has got one shoulder which act as reference surface and is held firmly and perpendicular to the center

line of the hole. Here also for larger ranges of measurements, extension rod are used. The screw micrometer depth gauge has range of 20mm or 25mm. The length of the micrometer depth gauge varies from 0to 225mm.The rod is inserted through the top of  the micrometer. The rod is marked after every 10mm so that it could be clamped at any position in using this instrument, firth it must be insured that the edge of the hole is free from barrel

DIAGRAM OF MICROMETER DEPTH GAUGE

[4]

 

 Plese see the video of depth micrometer and its least count.

 

PROCEDURE
1. To measure the depth of any material, use the micrometer depth gauge.
2. Take the sample piece, the length of the rod variesfrom 0 to 225mm.
3. Various rods are used as per requirement at the certainlimit that gauge will move as it
is by rotating screw in clockwise direction.
4. Tight the screw and measure the main scale and circular scale also adding the initial
value of rod this gives MSR, VSR and TSR by adding LC
5. Note down reading by following procedure.
OBSERVATION TABLE

  
RESULT
Linear measurement using vernier caliper, vernier height gauge and micrometer (internal
and external depth) are successfully completed.

Part B:-  Angular measurement using Combination Set, Bevel Protractor , Sine Bar and Clinometers

BEVEL PROTECTOR

It is use for measuring &lying out of angles accurately and precisely within 5 minutes. The protector dial is slotted to hold a blade which can be rotated with dial to the required angle and also independently adjusted to any desired length. The blade can be locked in any position.

  SINE BAR

The sine principle uses the ratio of the length of two sides of a right triangle in deriving a given angle. It may be noted that devices operating on sine principal are capable of self generation. The measurement is usually limited to 45 degree from loss of accuracy point of view. The accuracy with which the sine principle can be put to use is dependent in practice, on some from linear measurement. The sine bar itself is not complete measuring instrument. Another datum such as surface plate is needed, as well as other auxiliary instrument, notably slip gauge, and indicating device to make measurements.

 Checking of Unknown Angles :- 

Many a times , angle of component to be checked is unknown. In such a case it is necessary to first find the angle approximately with the help of a bevel protractor. Let the angle . Then the sine bar is set at an angle () and clamped to an angle plate. Next the work is placed on sine bar and clamped to Angle plate as shown in figure. Slip –gauges are so arranged ( according to deviation) that the sprit level is at center ( the air bubble )

If the deviation is noted down by the spirit level is h over a length ‘l’ of work , then height of slip gauges by which it should be adjusted is equal to = h 1

Precaution In Sine Bars :-

(a)  A Compound angle should not be formed by miss dignity of w/p with the sine bar. This can be avoided by attaching the sine brand work against an angle plate.

(b)  Accuracy of sine bar should be ensured.

(c)  As far as possible longer sine bar should be used since4 many errors are reduced by using longer sine bar.

 Combination Sets :-

 The combination set consists of scale , squaring-head, protractor and center-head. It consists of a heavy scale , which is grooved all along it’s length . It is on this groove that sliding squaring head is fitted . One surface of the squaring head is always perpendicular to the scale and it can be adjusted at any place by the locking bolt and nut. The squaring head also contains a spirit level which is used to test the surfaces for parallelism. For laying out dovetails an included angle is also mounted on the scale . It can also slide to any position and be locked there. A scribing point is also inserted into the rear of the base for scrubbing purposes. The squaring head and scale can be used for height and dept measurement, inside and outside squaring operation.

 [5]

Please see the video for measurement on combination sets 

 Slip Gauges:- 

Slip gauges or gauge blocks are universally accepted end standard of length in industry. These were introduced by Johnson, a Swedish engineer, and are also called as johanson gauges. Slip   gauges   are   rectangular   blocks   of   high   grade   steel   with   exceptionally   close tolerances.   These   blocks   are   suitably   hardened   through   out   to   ensure   maximum resistance to wear. They are then stabilized by heating  and cooling successively in stages so that hardening stresses  are  removed,After  being  hardened  they  are  carefully  finished  by  high  grade lapping to a high degree of finish, flatness and accuracy. -For  successful  use  of slip  gauges  their  working  faces  are  made  truly  flat  and  parallel.  A slip gauge is shown in fig. 3.36. Slip gauges are also made from tungsten carbide which is extremely hard and wear resistance.-The cross-sections of these gauges are 9 mm x 30 mm for sizes up to10 mm and 9 mm x 35 mm for larger sizes. Any two slips when perfectly clean may be wrung together. The dimensions are permanently marked on one of the measuring faces of gauge blocks.

Application of Slip Gauges:- 

1.Direct precise measurement, where the accuracy of the work piecedemands it. 

2.For  checking  accuracy  of  vernier  callipers,  micrometers,  and  such  other  measuring instruments. 

3.Setting up a comparator to a specific dimension. 

4.For measuring angle of work pieceand also for angular setting in conjunction with a sine bar. 5.The distances of plugs, spigots, etc. on fixture are often best measured with the slip gauges or end bars for large dimensions. 

6.To  check  gap  between  parallel  locations  such  as  in  gap  gauges  orbetween  two mating parts.

 

COLINOMETERS

A clinometers is a special case of the application of spirit level in colinometer; the spirit level is mounted on a rotary member carried in housing. One face of the housing forms the base of the instrument. On the housing, there is a circular scale. The angle of inclination of the rotary member carrying the level relative to its base can be measured by this circular scale. The clinometers is mainly used to determine the included angle of two adjacent faces of work piece. Thus for these purpose, the instrument base is placed on  one face and the rotary body adjusted till zero reading of the bubble is obtained. The angle of rotation is then noted on the circular scale against the index. A second reading is then taken in the similar manner on the second face of work piece. The included angle between the faces is then the difference between the two readings.

 Precautions :-

 1.               Angle of instrument must coincide with the angular scale

2.               Gripped the instrument to the measuring face exactly

 Result :-

To Perform angular measurement using sine bare with slip gauge study of clinometers , angle , gauge , combination set and bevel protractor is successfully completed

 

References:- 

1. Vernier height gauge | How to measure height and least count? - YouTube

2. https://www.google.com/url?sa=i&url=https%3A%2F%2Fth.misumi-    ec.com%2Fvona2%2Fdetail%2F223000297601%2F&psig=AOvVaw0siuF8msXg2-ZsfKTdxM38&    ust=1597123538407000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCOCrqPXyj-    sCFQAAAAAdAAAAABAK

3. https://www.google.com/url?sa=i&url=https%3A%2F    %2Fwww.mechanicalmeasuring.com%2Fmicrometer-parts-main-    function%2F&psig=AOvVaw02MwnUBPyr5tmjX-EQCBtV&ust=1597123623886000&    source=images&cd=vfe&ved=0CAIQjRxqFwoTCKjNmp3zj-sCFQAAAAAdAAAAABAD

4. https://technologystudent.com/images3/micrm11.gif

5. https://4.imimg.com/data4/IA/YD/MY-5401561/mitutoyo-180-907-combination-square-    set-500x500.jpg