General Purpose Tools Part 01- Shaping and Cutting Tools

     

GENERAL PURPOSE TOOLS

      INTRODUCTION

     Hand tools used by General mechanics can be classified under three classes,

            a.         Shaping and metal cutting tools.

            b.         Marking and measuring tools.

            c.         Tools used for dismantling and assembling.

 

         SHAPING AND CUTTING TOOLS

     Bench Vice

 

a.                Purpose

Although Bench vice is not a shaping or cutting tool, this is a very essential tool used to hold the material or job firmly.

b.        Classification

                        Bench vice is classified by Length of Jaws and Weight.

            c.         Construction

The body is made of malleable cast Iron or cast steel. ­Detachable Jaws are hardened and Tempered screw - Is made of mild steel having a single, start, buttress or square threads, Quick Release mechanism is to release the jaws quickly.

    HAND VICE

      a.         Purpose

Used for hold small jobs as screws, rivets etc.          

a.                  Classification

Classified by the weight and overall length.

b.                  Construction

The body is made of steel with jaws – Hardened and Tempered of mild steel.

   Hand Vice

    HACK SAWS

a.         Purpose

To cut or part off materials to required size.

      b.         Classification

(1)        Handle - By the construction fixed or adjustable.

(2)        Blades - Are classified by the length and number of teeth per inch.

a.         Course blade - (14-18 Teeth per inch)

b.         Fine blade - (14-32 Teeth per inch)

c.         Construction

(1)        Frame

            It is designed to hold blade, and may be adjustable for different length blades can be obtained in two styles pistol grip and straight. Frame is usually made of medium Carbon Steel.

(1)               Blade

Blades are have holes in both ends, and are mounted on pins attached to the frame Blades should be installed in the frame with the teeth pointing forward. Hack saw blades are made of High grade tool steel or tungsten steel and are available in sizes from 6 to 16 inches two types of blades are available.

    HAND SNIPS

            a.         Types

                        (1)        Aviation Snips

Used for cutting heat treated Aluminum Alloy and stain less steel, and for cutting small circles and Irregular out-lines. This may be right or left hand.

Aviation Snips

(2)        Straight Snips

      Used for cutting straight lines.

Straight Snips

(1)               Circle Snips and Hacks-Bill Snips.

      Used for cutting inside of curves or radial.

Circle Snips and Hacks-Bill Snips.

CHISELS

Chisels

a.         Purpose

Use for cutting and chipping any metal softer than the chisel itself. This can be use in restricted areas and for shearing rivets.

b.         Classification

                        Classified by the types.

Ø    Flat chisel

Ø    Cross cut chisel

Ø    Diamond point

Ø    Half Round

Flat.

                              These chisels are used for general chipping work, such as parting sheet metal or cutting flat surfaces preparatory to filing. The cutting edge is formed slightly convex.

Cross-Cut.

                 This type is used for cutting narrow flat-bottomed grooves, such as keyways in shafts, or where it is. Not practicable to use a flat chisel.

Diamond Point.

                               These chisels are particularly useful for cutting in corners, cutting small oil grooves, and rectifying an incorrect start when drilling.

Half-Round

These are general-purpose grooving chisels which are very suitable for cutting half-round bottomed grooves;

 

    FILES

 a.         Purpose

Files are used to remove metal accurately to required size .to square ends. File rounded corners. Remove burrs from metal. Straighten uneven edges. File holes and slots and smoother rough surfaces.

 

             b.        Classification

By length; section; cut and grade.

 

            c.         Construction

Files are made of high grade tool steel hardened and tempered-blade and tang left soft. Length is measured from heel to the tip of the file. Tang is not included.

SECTION (Shapes)

                                          Types of section of file

(1)           Hand or Flat.

These are slightly tapered toward the point and single cut in on edges and double cut in on both sides. The safe edge has no teeth.

(2)           Square Files.

May be tapered or blunt and is double cut. Used for filing circular opening or concave surfaces.

(3)           Round or Rat-Tail.

           These are in circular cross section may be single or double cut, either tapered or blunt. Used for filing circular openings or concave surfaces.

(4)           Triangular Three Square.

Triangular in cross section may be single cut or double cut used for filing, gullet between saw teeth, internal angles clearing out corners, and taps and cutters..

(5)           Half Round.

           Cut on both flat and half round sides, may be single or double cut. Used for concave surfaces.                   

a.                Cut

                          Type of cut refers to the shape of the teeth of the file. There are four types of cut.

(1)               Single Cut

Has single series of teeth.

(2)               Double Cut

Has second series of teeth cut at an angle to the first.

(3)               Rasp Cut

Has series of raised individual teeth makes fast but rough cuts. Used on soft materials as aluminum and lead, where removal of material fast desired.

Types of file tooth cuts grade

    REAMERS

a.         Purpose

     REAMERS

b.         Types

                        Hand reamer (straight-fluted).

As square end shank so that can be turned with a tap wrench or similar handle used to smooth holes. Tapered Reamer used to aid in. starting.

(1)                 Shaping Procedure

Bottoming reamers are used to complete the reaming of blind holes. For accurate work fixed reamer with standard size is employed and obtained in increments of 1/64”.Spiral fluted reamer has fewer tendencies to chatter.

Expansion reamer (Adjustable reamer)

Used when the technician requires to size a hole slightly .larger than a standard measurement. Available in standard sizes from 1/4” to 1 inch by 1/32-inch increments.

(2)         Construction

Reamers are made of either Carbon tool steel or high-speed steel, blades are hardened to the point of being brittle.

 

(3)        Operation

                                    Hole to be reamed to exact size must be drilled about 0.003 to 0.007 inch under size. When reaming a hole rotate the reamer in the cutting direction only. Turn the reamer steadily and evenly to prevent chattering marking and scoring of the hole walls.     

a.                Precautions

            Must be handle with great care should never be placed in a rack or tool box. Reamer should be -provided- with a case of soft material, or should be placed in a separate space provided in a wooden reamer box.

 

    TAPS AND DIES

These are used to cutting internal and external thread by hand.

            a.         Tap

(1)        Purpose

            Taps are used to cut threads on the inside of a drilled hole.

(2)        Types

i.          Taper Tap

Taper tap is used to begin the tapping process it is tapered back for 6 to 7 threads. This tap cuts the complete thread.

ii.         Plug Tap

Plug tap is used when the hole is blind, and the user wants to cut the thread nearer the bottom than is possible with taper tap.

            iii.        Bottoming Tap

This is not tapered. It is used to cut full threads to the bottom of the blind hole.

(1)               Construction

Taps are made of High Carbon steel Hardened and tempered, and ground to an exact size. Four-types of threads are cut in standard taps. Course and fine.

(2)               Tapping Procedure  

After drilling the hole, proceeded on with the tapping operation as follows Ensure the work is held securely. Enter the tap perpendicular to the face of the work and turn it carefully in the cutting direction, until the thread start is made. Test the entered tap for square with the aid of Fitter Square.

Turn the tap in the cutting direction for half a turn (1800) and then in the reverse direction a quarters. This prevents over straining the tap and breaks burrs in to chips. Repeat the operation until full thread has been cut, changing second a tap.

a.                Dies

 

(1)               Purpose

Used to cut external threads on metal rod stock .It is used in conjunction with special wrench called stock.

(2)        Types

i.          Solid Die

This has no provision for adjustment .Used for cutting thread on small Diameter rods.

ii.         Adjustable Die

Adjustable die can have small adjustments made to it

Die set

(3)        Construction

                                    Made of high Carbon - steel hardened and tempered.

 

            (4)        Thread Cutting Procedure

The rod to be threaded is held securely in a vice and light oil is applied to the end Starting side of the die is placed over the end of the rod and is turned in a clock wise direction.

 

From time to time the direction of the die movement is reversed. To clear the threads of metal chips.

Thread Cutting Procedure

(5)        Die Nut

            Used to clean the (damaged) thread Die nut is similar to ordinary hexagonal nut, and are available in all sizes of standard screw threads.

     HAMMERS

A hammer is a tool meant to deliver an impact to an object. The most common uses are for driving nails, fitting parts, forging metal and breaking up objects. Hammers’ are designed for a specific purpose, and vary widely in their shape and structure.

a.                  Purpose

 

                        It is used forming soft metals and striking surfaces.

b.         Classification

                        Hammers are classified by type and the weight of the head.

            c.         Types.

(1)               Ball Peen

 

Combination of flat face and the rounded been makes the ball been hammer useful fore variety of metal forming tasks. Head is made of tough steel to permit its use in pounding against other steel parts such as punches and chisels.

(1)               Cross Peen And Straight Peen

 

            These hammers are used in sharp comers or narrow restricted areas.(Peen may be spelled as Pain or Peen)

(1)               Soft Hammers

 

Soft hammers are made with heads or faces of plastic raw-hide wood­ brass copper lead or rubber. These are designed to apply moderately heavy blows to various materials including metals without causing damage .Soft Hammers are used for -forming metal ­separating tightly fitted parts ,Assembling parts, where a tight fit is required. Removing tight fit bolts and variety of other job.

Main purpose of using the soft hammer is to prevent damage to the surface. Use of wrong hammer can cause damage to the .material and personal injury to the user.

Please continue reading with part 02 ........