Wednesday, July 3, 2013

Workshop Maintenance Tools..Definite Read! Part-2

WorkShop Tools Part-2

Maintainence Tools
(content courtesy: www.splashmaritime.com.au)

Declaration: All material published here is owned by splashmaritime.com.au. It is shared here for educational purposes only!

Hammers

Hammers impart a force either directly or indirectly through another tool such as a chisel or punch to a workpiece. The most common hammers used are:

Soft Faced Hammers
Hammers with copper, rawhide or plastic are suitable for panel beating, shaping thin metal sheet and assembling finished parts to give a light force fit. Soft Headed Hammers (rubber) are suitable for positioning work where you do not want the hammer to rebound

Claw Hammers
Claw hammers with jaws at the reverse of their heads are suitable for nailing, striking all metal chisels and extracting nails.

Ball Pein Hammers
The ball pein or engineers hammer is the most common of the hammers used by mechanical trades persons. It has a convex face for striking tools such as punches, chisels, centre punches or theworkpiece itself. The opposite end of the hammer head is a hemispherical ball pein used to dome or shape the shanks of rivets or to stretch the surface of a metal workpiece to straighten it.

The weight of the hammer must be chosen to suit the job. For example, where a heavy blow is required in a confined space, a heavy hammer should be used because its large mass will be able to deliver a large amount of energy to the workpiece or tool without being made to move fast.


The hammer handle should be in good condition and of a size that is comfortable to use.
It should be square with the head and fit tightly into the head. The hammer should not be used if either the head or the handle is damaged, because a burred or chipped head will cause injury if it hits the hand holding a tool such as a chisel, while a split handle may injure the hand holding the hammer.

Cross Pein Hammers
A special purpose engineering hammer that comes in a variety of masses up to 450 g (1 lb). Larger sizes are called sledge hammers and are suitable for driving a large shafts out of a pullies etc.The cross pein hammer is also used in confined spaces or for straightening or stretching when the metal is peined at right angles to the direction of stretch or curve.


Text Box:  Text Box:


















Ball pein hammer                                               Cross pein hammer

Cutting Tools

Chisels

Cold chisels are forged from tool steel. Only the point of the chisel is hardened and tempered, the body being left soft. If the head of the chisel were hard it would chip as the result of the hammer blows.

The point of the chisel if formed into a cutting edge. This cutting edge is similar in nature to other cutting edges in that it requires the edge to be sharp.









Cold chisel                                                                    Correct cutting angle and position



Clearance or relief angle is shown. The cutting action of a chisel is somewhat different from that of a lathe tool, in that the clearance or relief angle is determined by the operator in the manner that the chisel is held in relation to the work piece. The size of the cutting angle should be about 70° for soft steel; when chipping harder metals the angle should be a little larger and for softer metals it can be ground smaller.

Chisels selection
Flat chisel are used to cut out of  thin metal sheet. Diamond‑point and round‑nose chisel chisels can draw‑over a drill point that has begun to cut off centre. Diamond‑points also can chip out a weld that has cracked.  Cross‑cut chisels can cut out the length of a narrow groove.

 Care Of Chisels
Because chisels are subjected to continual impact loads, they are likely to show signs of metal fatigue or cracking after a period of use. In this condition they will become dangerous as small pieces of metal or splinters may fly off at high speed causing injury to the operator or to people standing nearby.
A new chisel should be used lightly until it is proved to be sound and only then should heavy blows be used on it.
A major problem associated with the use of chisels is the mushrooming of the head due to the fact that the head is soft and the constant hammering on the head distorts the metal as shown in. The head of the chisel should be kept in good repair by keeping the chamfer ground cleanly.

When resharpening a chisel care must be taken not to raise the temperature of the cutting edge above the temper temperature. Ideally when grinding a chisel cutting edge no colour should show on the surface but a very light straw colour would not reduce the hardness of the chisel edge.













Mushrooming is a dangerous condition



Text Box:
























Six common chisel shapes

Files


Files are used to reduce or smooth the surfaces of the work. They are made from a high grade tool steel and pass through a process which includes forging, dressing of the surfaces by filing or grinding, forming of the teeth and heat treatment.

They are very hard and brittle and must not be used as levers, packing or wedges, nor should they be hit, because of the danger of shattering.






Outline views of a flat file


Convexity Of A File
Most files are made with their faces slightly “bellied” or convex, along the length.





The belly on a file


Slight warping is likely to occur during heat treatment and if files were cut perfectly flat, one side might be concave after heat treatment and be useless for filling flat.

If perfectly flat in the natural state, the pressure applied at the ends when filing would cause the file to bend and become concave on the cutting face while the operation was in progress.

The convexity of a file restricts the number of teeth which contact the work surface and thus reduces the load required to make the teeth penetrate the surface of the work.

The convexity will make a small allowance for the tendency to rock the file as it is used, and will thus make it easier to file flat.


Single Cut And Double Cut Files
The teeth of a file are formed in one of two ways in that they maybe “single” cut or “double” cut.







Single cut                       Double cut


The teeth of a single cut file extend from one edge of the file to the other without interruption. This broad, continuous tooth has a scraping action on the work surface and produces a good finish. The teeth of a double cut file are pointed and are able to bite more deeply into the work surface than the single cut file. They are able to cut quickly and do not clog (that is, become “pinned”) as easily as the single cut file. Most files are double cut.


Coarseness Of Cut
For the more commonly used files, the coarseness of cut is defined by name: rough, coarse, bastard, second cut, smooth and dead smooth. The most commonly used grades of cut are bastard, second cut and smooth. Figure 10 shows a comparison between these grades.


                                  Bastard




                            Second Cut





                                   Smooth



These terms, expressing the grade of cut of a file, are related to the size of the file in that a 300 mm second cut file is coarser than a 150 mm second cut file. The cut of very small files is classified by numbers. Nos 00, 0, 1, 2, 3. 4, 5, 6, 7 and 8. No. 00 is the coarsest. The most commonly used grades are Nos 0, 2, 4 and 6.


File Shapes And Types
Files are made in a wide range of shapes and types, some for general purpose use and others for special applications.


The Common File Shapes

Flat File:
Tapered in width and thickness, double cut, used for general purpose filing.

The flat file



Hand File:
Tapered in thickness only, sides parallel, no teeth on one side (i.e. one safe edge), double cut, same application as the flat file.

The hand file.


Square File:
Tapered on all sides, double cut, used for roughing down flat surfaces and enlarging square holes.

The square file


Round File:
Tapered, single or double cut, used for enlarging round or curved holes.

The round file

Half Round File:
Tapered, double cut except that those finer than bastard cut are single cut on the convex surface. It is widely used because of its combination of flat with curved surface and ability to reach into restricted openings.

The half round file

Three Square File:
Tapered, double cut, triangular cross sectional shape, used for filing sharp internal angles.

The three square file


Warding File:
Tapered on edges only, double cut, its thin section allows it to reach into narrow slots.

The warding file


The Size Of A File
The size of a file is specified by its length as measured from the heel to the point.


Classification Of A File
In general, files are classified by length, name or type and grade of cut.
For example:      300 mm flat second-cut file
                            200 mm half round bastard cut file.


Care Of Files

Storage
Files should be stored in a clean, dry place to avoid the possibility of rusting or having oil or other liquids come in contact with the cutting face.
The cutting edges of a file must be protected from damage by keeping files separated from other files or hard metals. That is, they should not be placed or thrown across each other on the work bench or stored by bundling them together in a draw.
It is good practice to clean files before storage so that they are ready for use when needed.


File Safety
Never use a file as a lever. Files are very hard and brittle and are likely to snap if used in this way.
Never use a file without a correctly fitting handle as the tang of the file is likely to pierce your hand as you push forward on the working stroke.
A poorly fitted handle can come off the tang on the return stroke in which case you may loose balance and fall over or suddenly find yourself pushing forward towards an exposed tang.
Never use a file with a split or splintered handle.



Removal Of Scale
Scale on black steel is hard and abrasive and will quickly spoil the sharpness of the cutting edges. The cutting edges can be protected by removing scale from the surface of the workpiece with the edge of the file or with an old file or in some cases with a hammer and chisel.

Order Of Use
It is good practice, where possible, for the first use of a file to be on softer materials such as brass, bronze or grey cast iron, and after it has lost its initial sharpness to use it on steel.


Pinning
Particles of metal are likely to wedge in between the teeth of a file. This is called “pinning”. These particles of metal may stand higher than the teeth and can cause scratches in the work surface. Pinning can be minimised by rubbing chalk into the face of the file.


Cleaning Files
Files can be brushed and cleaned with a small stiff brush known as a “file card”









Hacksaws

Hacksaw blades are made from alloy tool-steels and high-speed steel. The blades are available in two types. These are:
All hard:
The “all hard” type blade is hardened throughout and is more rigid than the second type. It is recommended where the workpiece is securely supported and an accurate cut is required.

Flexible:
The flexible blade is hardened on the cutting edge only, the remaining portion of the blade being in a toughened state.


The blades are unbreakable in normal use and are preferred where the workpiece is not securely held or where the operator is unable to control the movement of the saw properly.
















Pitch Of The Teeth:
Hacksaw blades are made with a range of tooth pitches to enable them to cope with a variety of job situations.

Material to be cut
Hard  - 
Alloy & High Carbon Steel
Medium Hard  - 
Mild, Medium Carbon Steel


                                     Up to 3mm

32  TPI

32  TPI




                                    3mm - 6mm

24  TPI

24  TPI




                                  6mm - 13mm

24  TPI

18  TPI


             
                                13mm - 25mm

18  TPI



14  TPI





The Hacksaw Frame
The hacksaw frame is either fixed in length to take a certain length of blade or adjustable and able to take a range of blade lengths. The frame shown below is an adjustable frame.























Blade holding piece may be set in any of four positions



All hacksaw frames have a means of tensioning the blade because it is most important that the blade be properly secured.

If the blade is not tight enough the downwards cutting load will unduly bend it and it will likely break. It will also be difficult to guide the blade, during the cut, because of its lack of stiffness. Over tightening of the blade will also lead to blade breakage.

The blade will be sufficiently tight when it cannot be easily deflected by either the fingers or the cutting force.

When the hacksaw is not in use the tension should be let off the blade and frame by loosening the wing nut by one or two turns.


Hacksaws, like any other tool require regular maintenance. The tension piece and wing nut should be cleaned and lightly oiled from time to time and the handle should be checked for any burrs, sharp edges or splinters or cracks if it is a wooden handle.

Snips

Tin snips or snips are used to cut sheet metal. They come in a variety of styles for different cutting operations.

The two main types of snips are universal snips and aviation snips.













                  Universal snips                                                                 Aviation snips


Both these types of snips may be obtained in right hand or left hand cut, and in straight or offset stylet. Th figure below shows the correct side the waste should be on when using right hand or left hand snips.













Safety With Snips
When cutting sheet metal, sharp edges are formed that can cut a hand or finger very easily. Therefore take extra care when cutting with snips, that your hand or fingers are well clear of the sharp metal edges.

Some snips have handles that come together when the snip is closed. Ensure that the palm of your hand will not be nipped by the handles when they come together.

Care Of Snips
Only use snips for the material they were designed to cut. Never use snips to cut wire as the cutting edge will be nicked and further clean cuts will be impossible to make.

Keep the cutting edges in good condition by lightly honing with an abrasive stone or by regrinding on a bench grinder.

The pivot point should be kept lightly oiled and in good adjustment so that the faces of the blades slide together firmly with minimum clearance.


Cutters And Strippers
There is a wide variety of cutters which cut round metals up to approximately 13 mm in diameter, depending on the tool capabilities.

Cutters used for cutting round metals above 3 mm diameter are generally known as bolt cutters whereas cutters that are used to cut round metal below 3 mm diameter are side cutters. A range of cutters and strippers is shown in the figure below.














Strippers are used to remove (strip) the plastic insulation off electrical and other coated wiring.


Hand Taps

Hand taps are used to produce internal threads by hand.

Hand taps are made in sets of three and comprise a “taper” tap, an “intermediate” tap and a “plug” tap.

The driving end of the tap is formed into a square to take a tap wrench.













Taper            Plug           Bottoming

A set of hand taps


The tap wrench is adjustable to take a limited range of tap sizes; it is also double ended in that the driving force, from the operator’s hands, is applied to each end of the wrench. By applying a driving force to each end of the wrench, (i.e., by using a proper tap wrench and not a spanner) there is less chance of breaking the tap due to bending it, because the force applied by one hand balances the other. It is important to use the correct size wrench for a tap, because a large wrench will multiply the force of the hands up to a level where the tap may be overloaded and broken.


Tap wrench



The Tapping Hole Size
Before a hole can be tapped it must be drilled the correct size to allow sufficient metal in the hole for the thread to be formed by the tap. f too much metal is left in the hole it will make tapping difficult and increase the possibility of breaking the tap.

If not enough metal is left in the hole, the tapped thread will be weak and possibly be stripped when a bolt is tightened into it.

The correct size drill to use is best found by referring to tapping size drill tables and using the recommended size drill for the material and application.

A typical tapping size drill table is shown.


TAPPING DRILL TABLE
(Reproduced from the “Ajax Handbook” with the permission of the Ajax Fastener Co.)
To ease the strain of a tap the minor diameter of a nut thread should be produced by the recommended tapping drill



Dies
Three types of die are in common use:
•        The divided disc type which is made in two separate pieces. The two halves are attached to a guide plate which secures then and guides the die squarely onto the shaft to be threaded.
          The guide plate and dies are held in an elastic stock.
•        The button die, which is a disc in one piece, split on one side, is adjusted by means of a screw.
•        The die nut which is either hexagonal or square in shape, is operated by a spanner and is used only for cleaning a thread or for removing burrs. An exception is the pipe threading die nut which is used for thread cutting.













Scrapers

Scrapers are used to remove small inaccuracies in surfaces produced by the ordinary methods of machining such as turning, milling, shaping or planing, or by filing.

The scraper is, therefore, used where curved or flat surfaces must be fitted accurately to each other.

The scraper is sometimes used to give ornamental effects to machine parts even when they are not finished to a high degree of accuracy. Srapers can be made from tool steels or sinteredcarbide.Tool steels are more commonly used than is sintered carbide, because of their cheapness and ease of sharpening.

Scrapers are made in various forms, as follows:


The Flat Scraper
Flat scrapers are used for scraping flat surfaces. They range in size from about 150 mm to 300 mm or more in length. The tang should be fitted with a file handle.






The flat scraper



The Half Round Scraper
The half round scraper is designed for scraping curved surfaces such as bearings. It is made in a range of sizes.

As with other scrapers it should be fitted with a file handle.






The half round scraper



The Three Square Scraper
These scrapers are also used on curved surfaces, but usually small in diameter. The three square scraper is also used for removing burrs from the mouth of a hole while the job is in the lathe.

Three square scrapers can be easily made from a three square file.


The three square scraper


The Bull-Nose Scraper
Bull-nose scrapers are used for scraping large brasses or half bearings. This scraper, being round on the cutting edge end, can be used with the same action as the flat scraper and can also be used with the same action as the half round scraper. It is very useful as a roughing down scraper, but needs to be followed by a half round scraper for fine fitting.






The bull-nose scraper

 

 

Marking Out Tools


Engineer’s Squares
Engineer’s squares are available in a variety of sizes. They are accurately made with an angle of 90°. Squares are used to mark out right angles and to check internal and external right angles.












Adjustable blade square                                                                      Engineers trysquare                  






Combination Set
A combination set is made up of a steel rule, a square head, a protractor head and a centre square head. The steel rule is used in whichever head is needed for the job at hand. The square head will also give accurate 45° angles.
















Centre Squares
Centre squares are used to mark out the centre of round material.


Centring a disc






Protractor
A protractor is used for marking and testing angles. They can be ordinary protractors as shown, part of a combination set or vernier protractors.















Scriber
Scribers are made from hardened steel. They are used to mark clear, sharp lines into metal surfaces. A rule, square or other surface is used as a guide for the scriber.







                     

                   



Double edge engineer’s scriber                                              Pocket scriber




Dividers
Dividers have hard points. They are used to scribe clear and sharp circles and arcs into metal surfaces.













                                               
Spring dividers                                                     Winged dividers


Trammels
Trammels are used to mark out large diameter circles.










         







Hermaphrodite Callipers (Jenny, Odd Leg Callipers)
Hermaphrodite callipers have a hardened point which is used to scribe lines in metal surfaces. They are used to find the centre of round material or to mark a line parallel to an edge.











Prick And Centre Punches

A prick punch has a smaller diameter point than a centre punch which is ground at an angle of 60º. It  is used to lightly mark marking out lines so they don’t disappear during other work. A centre punch is used to make a large indent for starting a drill and is ground at an angle of 90º. A pin punch is used to drive out loosened taper pins. Taper drift punches will drive out tight parallel pins.         

                                          





                  Centre punch                   Prick punch                                    Pin punches

 

Care Of Hand Tools


Safety
For any job, select and use the hand tool that will allow the job to be done safely and within a reasonable amount of time.


Always use the hand tool for the job it was designed for. Example, do not use tin snips to cut wire instead of side cutters simply because they may be close at hand.

Good job planning will ensure you have the correct tools on hand when required during the job.

Always use the tools safely and wear appropriate safety clothing and personal protective equipment.


Storage
To prevent damage to hand tools during storage, manufacturer’s recommendations should be followed. These usually include:
•        protection of cutting edges and points by covering with a soft or plastic covering
•        cleaning before storage
•        application of a rust inhibitor where appropriate
•        store in individual compartments/sleeves to prevent damage through contact with other tools
•        release of tension where needed.

Where a number of people share hand tools, the tools should always be returned to the same place in good working order.


Faulty Tool Procedures
Faulty tools should be taken out of service immediately and repaired or replaced at the earliest possible time.

Never put a tool back into store or in a toolbox if it requires repair.

Where a fault is obvious or suspected, a qualified person should determine whether the tool can be repaired or needs to be replaced.

Repairs should only be done by someone with the necessary skills and/or training. Replacement tools should be obtained through normal workplace procedures.

Faulty tools should be tagged or marked so they are not used while faulty.

Faulty tools that cannot be repaired should be made inoperative to prevent accidental use.

Routine Maintenance
Routine maintenance of hand tools involves keeping the tools in good working condition. This may involve:
•        sharpening
•        removal of burrs or unwanted sharp edges/corners
•        cleaning
•        lubricating moving parts
•        applying rust preventative
•        checking and adjusting settings.

3 comments:

  1. All the three articles in the series are very well written!!!
    Covering almost all the tools used onboard and more. With just the right amount of explanation on its use, maintenance and safe practices.
    Definitely a Definite read!! :p

    ReplyDelete
    Replies
    1. Mr jayant negi, I am really thankful to you for appreciation of our work.
      This will encourage us to produce more and more articles for the benefit of marine world.
      God bless :)

      Delete
  2. You must not try missing any opportunity of getting the wide range of MIG welders for sale Ireland through the online store of Jebb Tools, a unique store that provides the exclusive collection of tools of various kinds.

    ReplyDelete

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