FITTING SHOP
INTRODUCTION:
In fitting shop, proper shape and finishing of specimen is done. There are various tools used in fitting shop, which perform these operations. This shop is very important as various metal pieces are given proper shape and finishing for further operations as turning, milling etc. Thus, a fitter should have complete knowledge of tools used and operations performed in fitting shop. Tools used in fitting shop are: 1.Measuring tools. 2.Cutting tools. 3.Surface measuring tools.
1.Measuring tools: These tools are used for measuring various sizes or
comparing different sizes of identical parts to check their mating or to check errors in their manufacturing. These are further classified as: a. Vernier caliper: - It is used for checking internal or external measurements of different articles. They are made in lengths of 150, 200, 300, 400, 500, 600, 800, 1000 and 1200 mm sizes.
b. Vernier Depth Gauge: - It is similar to vernier caliper except that it is used to measure depth of holes or thickness of components. c. Micrometers: - These are designed for measurements having accuracy up to 0.01 mm.
2.Cutting Tools: They are used to remove metal from blanks in form of
blanks in form of chips to bring it to desired shape and size. Commonly used cutting tools are: a.Chisel: They are used for chipping and cutting away metal. Forging, rough grinding, hardening and tempering make them. The cutting angle varies between 35 and 70. b. Files: - File is a hardened piece of high-grade steel with slanting rows of teeth cut on it. The teeth are cut with a sharp chisel having a point angle of 55 to 60. c. Hacksaw: - It is an important tool used to make long cuts. It consists of a blade having cutting teeth fixed to a frame, which may be adjustable or nonadjustable. The blades are either made of carbon or high speed steel. d. Scraper: - It is used to remove metal flake by flake from a surface to make it fine and smooth. It removes thin chips. e. Drills: - These are used to produce round holes in metal. These are mainly of three types:
I. Flat Drill. II. Straight flute drill. III. Twist Drill. Out of these, twist drill is most commonly used. f. Reamers: These are multitoothed tools used for finishing and enlarging previously drilled hole. These are classified accordingly to operation, purpose and shape as: I. Parallel head reamer: - It has cutting edges parallel to axis with front teeth slightly tapered for easy operation. II. Parallel machine Reamer: - It is similar to above reamer except length of teeth is small and has a straight parallel shank. III. Taper pin reamer: - The fitting edges are tapered for hole to suit pins with a taper of 1 in 50. g. Scriber: - It is a piece of harden steel about 150 to 350 mm long and 3 to 5 mm in diameter pointed on both sides like a needle. One side is generally bent at right angles. This side is used to scratch lines in places where straight portion cannot reach.
h. Spanners: - These are used for scribing circles, marking off and lengths.
3.Surface measuring tools: These are used for checking deviation of a surface from horizontal or vertical plane and for checking straightness of surfaces. Spirit levels are most commonly used for testing surfaces. In the process of checking, spirit level is placed on surface to be checked and deviation is read off scale in the glass tube. Placing level at several points checks long parts.
