Spanners (which are also often known as wrenches in some countries) will only do a job properly if it’s the right size for the nut or the bolt to be turned.
The size used to describe a spanner/wrench is the distance across the flats of the nut or bolt to be turned. There are two systems in common use, metric, in millimeters, and imperial, in inches. Each of the systems has a range of spanners/wrenches especially made for each one. The systems can be identified on the spanner/wrench by either a number for metric spanners, or a fraction followed by A/F.
Another system once widely used in the United Kingdom was the Whitworth system. It used fractions but they did not refer to the distance across the flats of the fastener. Some older British and Australian machines use Whitworth-size fasteners. Some Whitworth sizes are not interchangeable with metric or Imperial systems.
There are many types of spanners/wrenches.
Choosing the correct one to use to do the job usually depends on two things: How tight is the fastener? In other words how much force is going to be applied to it, and, how accessible is it? - how much room is there to get the spanner onto the fastener, and then turn it.
When being used it's always possible a spanner/wrench will slip. Always try to anticipate what will happen if it does before putting a lot tension onto it. If possible, always pull a spanner/wrench towards you rather than pushing it away.
Ring spanners grip a fastener at the corners just like a socket spanner, just the sort of grip that is needed if a nut or bolt is very tight. Ring spanners have different sized heads at each end. They aren't as convenient as sockets but can fit into places that a socket can't. One disadvantage of the ring spanner is that it can be awkward to use once the nut or bolt’s been loosened.
Open end spanners/wrenches slip easily and quickly onto fasteners, and that's particularly important for nuts and bolts in awkward places. The angle on the head allows it to be used in two different positions. While an open-end spanner often gives the best access to a fastener, if it's extremely tight the open-end shouldn't be used as this type of spanner/wrench only grips across two flats. If the jaws flex slightly or the flats don't fit tightly between them, the spanner can suddenly slip when force is applied.
The best way is to use a ring spanner to break such a bolt or nut free, then the open-end. The open-end spanner should only be used on fasteners that are no more than firmly tightened.
The
combination spanner/wrench provides the user with the best features of each of the other types. It has a ring on one end for gripping and breaking the fastener's hold, and an open ended spanner of the same size on the other end.
A variation on the open end head is the
flare nut spanner. It gives a better grip because the flats meet on 5 sides, not 2. The open 6th side lets the spanner be used on nuts and fittings associated with pipes and tubing. Don't use the flare-nut spanner on extremely tight fasteners as the jaws may spread, damaging the nut.
There is another type of universal adjustable open end spanner/wrench in use. Usually referred to as a
shifting spanner/wrench or simply "shifters", the lower jaw can be moved to fit any fastener size within the spanner range. Shifting spanners should only be used if the correct sized spanner is not available. Both the fastener and spanner could be damaged if they are used on really tight bolts or nuts.
Sockets are a good choice where the top of the fastener is reasonably accessible. The socket fits onto it snugly and grips it on all 6 corners and is the type of grip needed on any nut or bolt that’s extremely tight.
Sockets also come in
deep wall sizes . These are ideal for removing or tightening spark plugs or nuts screwed on to long protruding threads.
There is also a special socket that only has 6 flats instead of the common 12 point design. It’s specially made for impact wrenches that exert a lot more pressure than turning sockets by hand. Socket spanners always need an attachment to turn them. This is done by a range of accessories, many of which are included in socket tool sets.
The connection between the socket and accessory is made by a
square drive. The larger the drive, the heavier and bulkier the socket.
The quarter-inch drive is for small work in difficult areas. The three-eighth drive handles a lot of general work where torque requirements are not too high. The half-inch drive is for all-round service. The three-quarter inch drive is for large work with high torque settings.
Many fasteners are located in positions where access can be difficult. Many lengths of extensions are available to bring the drive point out to where a handle can be attached.
A
universal joint can be used with an extension and takes the turning force that’s to be applied through an angle.
A
speed brace is the fastest way to spin a nut on or off a thread by hand, but it can't apply much torque to the nut, so it's mainly used to remove a nut that's already been loosened, or to run the nut onto the thread until it begins to tighten.
The most common socket handle, the
ratchet, makes easy work of tightening or loosening a nut where not a lot of pressure is involved. It can be set to turn in either direction and it doesn’t need much room to swing it. It’s built to be convenient, not super-strong, so too much pressure could damage it.
For heavier tightening or loosening, an
adjustable offset handle or breaker bar , gives the most leverage.
When that's not available a
sliding tee-handle may be more useful. Both hands can be used, and the position of the tee piece is adjustable to clear any obstructions to turning it.
Safety first:
- When applying pressure to pliers, make sure your hands aren't greasy, otherwise, sooner or later, they're going to slip.
- Select the right type and size of pliers for the job. As with most tools - if you have to exert almost all your strength to get something done, then you're either using the wrong tool, or you're doing it incorrectly.
- If the pliers lets go, you're going to get hurt. At the very least you'll damage the tool, and the work.
- Pliers get a lot of hard use in the workshop, so they do get worn and damaged. That makes them inefficient and even dangerous. Always check the state of all workshop tools on a regular basis.
Combination pliers are made from 2 pieces of high carbon or alloy steel. They pivot together so that any force applied to the handles is multiplied in the strong jaws.
Some pliers provide a powerful grip on objects, others are designed to cut. Combination pliers can do both - that’s why they’re the most common type.
There are two surfaces for gripping flat or rounded objects, and two pairs of cutters. The cutters in the jaws should be used for softer materials that won't damage the blades.
The cutters next to the pivot can shear through hard, thin materials, like steel wire or pins.
Most pliers are limited by their size in what they can grip.
Beyond a certain point the handles are spread too wide, or the jaws can't open wide enough, but these
multi-grips overcome that with a moveable pivot.
A pair of multi-grips can get a comfortable grip on a range of objects, and there are 2 surfaces for things that are flat or round.
Vice grips are general purpose pliers. Put an object between the jaws, turn the screw until the handles are almost closed, then squeeze them together to lock shut. They can also be used as temporary clamps in case a free hand is needed elsewhere.
There are a few specialized pliers in most workshops:
Long-nosed pliers can reach tight spots that others can't.
Flat-nosed pliers, have an end that is flat and square on the the end or nose, while on the combination pliers the end is rounded. A flat nose makes it possible to bend wire, or even a thin piece of sheet steel accurately along a straight edge.
Circlip pliers have metal pins that fit in holes in a circlip. Squeezing the pliers compresses the circlip and fits it in its groove. There's also a special pair of
external circlips (right) that are sprung to push them open.
This type of cutters are called
Nippers, or pincer pliers. They have a cutting edge at right angles to their length. They are designed to get a grip on and cut through anything sticking out from a surface. Rolling them on the curve of the jaws gives leverage too.
Side cutters work with any length, on things like wire or a steel pins. They're the most common cutters in the toolbox but they shouldn’t be used on hard or heavy gauge materials.
Bolt cutters cut heavy wire, rods, and bolts. Their compound joints and long handles give the leverage and cutting pressure that’s needed for heavy gauge materials.
Tin snips are the nearest thing in the toolbox to a pair of scissors. They can cut thin sheet metal, and lighter versions make it easy to follow the outline of gaskets. Most snips come with straight blades but if there’s an unusual shape to cut there is a pair with left or right hand curved blades.
Aviation snips are designed to cut soft metals. They’re easy to use because the handles are spring loaded open and double pivoted for extra leverage.
Wrenches
A torque wrench is also known as a tension wrench.
It is designed to tighten bolts and nuts using the drive on the end which takes any sockets and accessories found in an ordinary socket set. It is used to tighten fasteners, to a pre determined tension (torque) by the use of a movable scale that allows how tightly the nut or bolt is being done up.
Whilst manufacturers don't specify torque settings for every nut and bolt, when they do, it's important, and that's why the torque wrench is such an important tool.
The pipe wrench grips pipes and tubes and it can exert a lot of force to turn them. Putting more pressure on this wrench tightens its grip more and more. The jaws are hardened and serrated, and increasing the pressure also increases the risk of marking or even gouging metal from the pipe.
A wheel brace is a specialized wrench. This model has 4 different sockets, 1 on each arm. Never hit or jump on a wheel brace when loosening wheel nuts. If the brace won't remove them, use an impact tool. When using the wheel brace, the force provided with your hands is adequate to secure the nuts properly.
This specialized wrench is an
oil filter removing tool, which gives that extra leverage when oil filters are tight.
Files
Files are often sold without handles, but they shouldn’t be used until a handle of the right size has been fitted. The handle should be checked before use. It can come loose, and it may need a sharp rap to tighten it up.
Clean hands will help avoid slipping. Hands should always be kept away from the surface of the file and the metal that’s being worked on. Filing can produce small slivers of metal which can be difficult to remove from a finger or hand, and acids and moisture from the skin can cause corrosion.
Depending on how hard or soft a material is, a special file may be needed. It’s no good trying to file something if the file is softer than what is being filed - softer metals like copper and aluminum can clog a conventional file.
What makes one file different from another is not just it's shape but how much material it’s designed to remove with each stroke. That depends on the teeth. The following are both flat files, the most common general purpose type, but their teeth are different.
The teeth on this coarse grade file (left) are longer, with a greater space between them. Filing this piece of mild steel removes a lot of material with each stroke. A coarse file leaves a rough finish.
On the right is a flat file, but its shorter teeth remove much less material on each stroke, and the finish is much smoother.
On a job, the coarse file is used first to remove material quickly, then a smoother file gently removes the last of it and leaves a clean finish to the work.
The full list of grades in flat files, from rough to smooth, is:
- rough
- coarse bastard
- second cut
- smooth, and
- dead smooth
Some flat files are available with one smooth edge, called safe edge files. They allow filing up to an edge without damaging it. Flat files are fine on straightforward jobs but files need to be able to work in some awkward spots as well.
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| A warding file is thinner than normal, for working in narrow slots. | A square file has teeth on all 4 sides, so you can use it in a square or rectangular hole. |
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| A square file can make the right shape for a squared metal key to fit in a slot. This is a three square file. It's triangular in section, so it can get into internal corners. | Curved files are either half-round, or round. This is a half round. Its shallow convex surface can file in a concave hollow, or in an acute internal corner. The fully round file, sometimes called a rat-tail file, can make holes bigger. Or it can file inside a concave surface with a tight radius. |
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Files should be cleaned after use. If they’re clogged, they can be cleaned by a tool that's really part of the family called a filecard or filebrush.
This is a thread file. It cleans clogged or distorted threads. It has 8 different surfaces that match different thread dimensions so the right face must be used. |
Torque wrenches
This is a torque wrench. It tightens bolts and nuts using the drive on the end, which takes any sockets and accessories.
What makes this a special way to tighten fasteners is a scale that shows how tightly the nut or bolt is being done up.
This head bolt is being tightened to a specified torque recommended by the manufacturer, as being tight enough to ensure that the nut won't come loose, and the parts are being held together firmly, but not so tight as to risk breaking the bolt or stripping its threads.
Manufacturers don't specify torque settings for every nut and bolt, but when they do, it's important, and that's why the torque wrench is such an important tool.
