Basic Fitting-Steel Rule-Scribes-Dividers-Calipers-Punch-ITI-fitter online note

1)- Steel Rule(Basic Fitting):-

i)- Engineer’s steel rule are used to measure the dimensions of work pieces.

ii)- It is made by Carbon Steel, Stainless Steel or Spring Steel.

iii)- Its both edges there is marking lines and with the help of these lines the jobs can be measured.

iv)- Its available in 150 mm, 300 mm and 600 mm.

v)-  The reading accuracy of steel rule is 0.5 mm and 1/64 inch. 

Steel rule

Types of rule:-

a)- Narrow steel rule:-

i)- Narrow steel rule is used to measure the depth of key- ways and depth of smaller dia.

ii)- Blind holes of jobs, where the ordinary steel rule can not reach. 

iii)- Its width is approximately 5 mm and thickness 2 mm.

iv)- Do not place a steel rule with other cutting tools.

v)- Apply a thin layer of oil when not in use.

b)- Short steel rule:- 

i)- Its available in a set of small rule having 1/4", 3/8" 1/2" 3/4" and 1" length pieces.

ii)- It is also available in metric system having a set set of pieces from 5 mm to 25 mm.

iii)- It is marked upto 32 parts(division) in a inch.

iv)- These pieces are used by holding in a holder.

c)- full flexible steel rule with tapered end:-

i)- This rule are used all mechanics. 

ii)- its tapered end permits measuring of inside size of small holes, narrow slots, grooves, recesses etc.

Different types of steel rule

Metric:-

i)- Micron 1μ = 0.001 mm, ii)- Millimetre 1 mm = 1000μ, iii)- Centimetre 1 cm = 10 mm, 

iv)- Decimetre 1 d.m = 10 cm, v)- Metre 1 m = 10 d.m, vi)- Decimetre 1 dam = 10 metre

British:- 

i)- Thousandth of an inch= 0.001", ii)- Inch = 1", iii)- Foot 1 ft = 12", iv)- Yard 1yd = 3 ft, 

v)- 1 furlong 1 fur = 220 yds, vi)- 1 mile = 8 fur.

2)- Scribers(Basic Fitting) :-

i)- We draw the lines on paper with pencil similarly to draw the lines on metal scribes is used.

ii)-  It is made of high carbon steel and is hardened.

iii)- Its 3 to 5 mm thickness.

iv)- Its both ends are sharp,hard and tempered.

v)- Its point angle is 10 degree to 15 degree.

vi)- Its length is 150 mm to 200 mm.

vii)- These are available in different size exa:- Straight Scribner, Bent Scribner, Adjustable Scribner, Offset Scribner, Pocket Scribner.

Different types of scriber

3)- Dividers (Basic Fitting):-

i)- Dividers are used for ascribing circles, arcs and for transferring and stepping off distances.

ii)- Dividers are available with a)- firm joints and b)- spring joints

iii)- The measurements are set on the dividers with a steel rule.

vi)- The sizes of dividers range between 50 mm to 200 mm.

vii)-  Dividers are specified by the type of their joints and length.

viii)- The distance from the point to the center of the fulcrum roller (pivot) is the size of the divider.

ix)-  Frequent sharpening with an oil stone is better than sharpening by grinding. 

x)- Divider legs do not Sharpening by grinding because it will make the points soft.

Divider

4)- Calipers (Basic Fitting):- 

i)- Calipers are indirect measuring instruments.

ii)- It is used for transferring measurements from a steel rule to a job, and vice versa.

iii)- Calipers are classified according to their joints and their legs.

a)- Joint:– i)- Firm joint calipers. ii)– Spring joint calipers 

b)- Legs:– i)- Inside caliper for internal measurement. ii)– Outside caliper for external measurement.

iv)- Spring joint calipers have the advantage of quick setting with the help of an adjusting nut.

v)- Inside measurement in inside caliper, and out side measurement in out side caliper.

Out side calipers and Inside Calipers

5)- Jenny calipers:-

i)- Jenny calipers have one leg with an adjustable divider point, while the other is a bent leg.

ii)-  These are available in sizes of 150 mm, 200 mm, 250 mm and 300 mm.

iii)- Jenny calipers are used – for marking lines parallel to the inside and outside edges and also used for finding the center of round bars.

iv)- The other names for this caliper are: - hermaphrodite calipers - leg and point calipers - odd leg caliper.

v)-  These calipers are available with the usual bent leg or with heel. 

vi)- Calipers with bent leg are used for drawing lines parallel along an inside edge, and the heel type is used for drawing parallel lines along the outer edges.

Jenny Caliper

6)- Punch:-

i)- It is used for permanent marking on a already marked job. 

ii)- It is made of high carbon steel or tool steel.

iii)- its point is hard and tempered.

iv)- Its body is like a octagon (eight sides) or round in shape with knurling over it. 

v)- It has three parts. (i) Head, ii) Body, (ii) Point.

 Types of Punch:-

(i) Center Punch (ii) Dot Punch (iii) Prick Punch (iv) Automatic Punch (v) Solid Punch (vi) Hollow Punch, (vii) Pin Punch vii) Bell Punch (ix) Drift Punch.

(i) Center Punch: 

i)- It is 4 mm to 12 mm in thickness and about 125 mm in length. 

ii)- Its some front position is tapered and pointed at 90° angle. 

iii)- Its center portion of body is having knurling. 

iv)- It is used for making drill center.

(ii) Dot Punch:- 

i)- It is also like center punch but its pointer has 60° angle. 

ii)- It is used to make permanent marking after scriber marking .

iii)- Prick Punch: 

i)- It is used for fine marking and mostly used in soft metal marking like aluminium, copper, brasses etc.

ii)- Its point is having 30° angle.

(iv) Automatic Center Punch: 

i)- It is a modern punch and while using it there is no need to strike hammer over punch head.

ii)- It is used for fine and accurate marking. 

iii)- It has spring and steel block setting that is whenever we put pressure on the punch it starts marking without hammering. 

iv)- The quantity of strike (pressure) can be adjusted by rotating its cap fitted to its back.

v)- Its point is either 60 or 90° .

v)- Solid Punch: 

i)- It is used to make holes in the sheet and these holes are not so accurate in size so it is used for rough Work. 

ii)- While doing hole in the sheet a nut is placed below the sheet. 

iii)- It is used in sheet metal and black smith work.

(vi) Hollow Punch: 

i)- It is used to make holes in soft sheet like board, leather, gas cut sheet, flat belts, soft metal non-ferrous metal and thin iron sheet etc. 

ii)- It is hollow from inside and available in different sizes as per hole.

(vii) Pin Punch: 

i)- It is longer and parallel in shape. 

ii)- It is used to draw out the pin etc. 

iii)- It is available in different sizes.

(viii)- Bell Punch:-

i)- This is used to find out center or mark on round rod.

ii)- Its front portion is like a bell and its sizes depend upon the circumference of rod.

iii)- A punch is attached to its center which is pushed by spring.

iv)- Size of punch depends upon its diameter and length. 

Different types of Punches