Modern wrenches are designed according to the laws of physics,
……..and although you may not always realize it, it would be almost impossible to remove tightly screwed-on fasteners if the shape, angles, and offsets on your wrenches were just slightly different.
So if you are shopping for wrenches, read on- because in this article we will explain the differences between various types of wrenches, and also what to look out for in terms of quality, fitness for their purpose, and what the different markings on wrenches mean.
Ever since the first wrenches were patented by Solymon Merrick in 1835, they have undergone many changes- from convoluted shapes that had more to do with art than engineering, to the highly efficient shapes, angles, and offsets we see today. Think about it: without wrenches of all sizes, types, and descriptions, we would not be able to hold cars, aircraft, or machinery together with bolt and nuts- simply because we could not fasten the bolts and nuts tightly enough to prevent everything falling apart.
Types of Wrenches
There are a great many types of wrenches, and each has its own particular uses, advantages, and disadvantages. The amount of offset between the centre line of the opening and the midline of the handle on an open ended wrench vary greatly between brands, but since the offset determines the amount of torque that can be applied without the wrench slipping off the fastener, it is important not to use wrenches with an offset of less than 5 degrees.
Wrenches also come in a variety of lengths to make it possible to work in confined spaces, but for the most part, all wrenches share most of their characteristics. Below is a short description of the various types of wrenches that are suitable for general DIY work around the house by car.
Open ended wrenches are those that have two different sized openings- one on each end. The main advantages of this type of wrench are that they are usually shorter than combination wrenches, which makes it easier to work in confined spaces.
In addition, open ended wrenches have openings that are close in size, which means that one wrench can be used for two fastener sizes. They also come in all the measurement standards, but beware that an open ended wrench cannot be used to apply the same force as with a combination wrench. Especially on soft materials like mild steel, an open ended wrench is likely to slip and round off the corners of the fastener.
As the name suggests, a combination wrench has a U-shaped open end on the one end, and a ring, or “box” as it is also known, on the other, and in all cases, the open and ringed ends are about the same size. Combination wrenches are also available in all measurement standards.
The advantage of combination wrenches is that it is possible to apply great force with the ringed end without damaging the fastener, and once loosened, the fastener can be further undone with the open end. Combination wrenches are sometimes fitted with ratchet mechanisms in the ringed end, which makes it possible to undo a fastener without having to remove the wrench from the fastener.
The best quality combination wrenches have an offset angle between the plane of the ring and the handle, which provides clearance between your hand and the work, to prevent skinning your knuckles, but also to increase the torque you can apply to the fastener.
In simple terms, a Pipe Wrench is an adjustable tool that is used in plumbing, to loosen or assemble pipe work that has no flat sides on which a normal wrench can find purchase.
Both jaws are serrated to improve grip on round pipes, but since the upper jaw is capable of some movement, the force with which the jaws grip the work piece increases as force is applied to the handle.
Pipe wrenches generally do not work well on fasteners with flat sides, and their use on normal fasteners must be avoided to prevent damage to the fastener, the tool, and your fingers should the wrench slip off the fastener. The size of a pipe wrench can be expressed both in inches and millimeters, and refers to the length of the handle. Pipe wrenches with a length of 12-,to 14 inches is adequate for most jobs around the house.
Size of Wrenches
Before the standardization of the sizes of fasteners, and especially the Imperial sizes, there were at least two dozen different standards in common use to measure the size of a nut or the head of a bolt. Many manufacturers of fasteners used proprietary standards, and you needed wrenches that were made especially for the products of that manufacturer. One good example is the “BSW” standard, which stands for “British Standard Whitworth”, and the wrenches made to this standard could not be used for any other standard, except by happy coincidence.
Today, however, only three standards, or measuring systems are in common use by industry worldwide, and they are:
In this standard, the sizes of nuts and bolts are measured in millimeters across the flats of the fastener, and the system is used in Japan, most of Asia, and all European countries, with the exception of England, where the SAE system is still widely used. However, the metric standard is fast gaining ground in England, and especially in the automotive industry.
The acronym stands for “Society of Automotive Engineers” and refers to the fact that the sizes of wrenches and sockets made to this standard increase in increments of 1/16th of an inch. The size of the fastener is also measured across the flats of the head, and it is mostly used in American industry.
Although the AF standard is becoming increasingly rare, it might still be found on cars and machinery made up to the mid-1970’s. Generally speaking, a wrench, marked with an AF size will fit a fastener that corresponds to the size stamped on the wrench-thus a ⅜ wrench will fit a fastener that is three eighths of an inch wide across its flats.
Guide to Buying Wrenches.
The first thing to remember when buying wrenches, or any other tools for that matter, is to buy the best quality that is available, as opposed to the best you can afford. Price is usually a very good indicator of quality, so avoid the cheaper brands. Below is a list of some other considerations to keep in mind when you are shopping for wrenches.
- Look for the “Cr-V” mark.
This mark refers to the alloying materials used in the manufacture of the wrench. “Cr” means that chromium was added to the base metal to assist in resisting rust and corrosion, and “V” refers to the vanadium that was added to increase strength.
- Look for offset wrenches:
Avoid wrenches that have no offset at the box end. The level of the handle should be above that of the “ring”, or box, to avoid the wrench slipping off the fastener when you apply force to a fastener.
- Look for full contact:
Avoid open ended wrenches if the sides of the opening does not make full contact with the total length of the flat sides of a fastener. Wrenches in which the opening is too short will round off the corners on almost any fastener, which could make it very difficult to loosen the fastener with anything else.
- Ask about lifetime warranties:
Some manufacturers guarantee their products for life, and provided that the tool was not used improperly, they will replace any tool free of charge if it is delivered to a dealer that sells their products- no questions asked. However, the tools of this quality are very expensive, but lesser quality tools simply do not work as well, which justifies the higher price.
- Buy wrenches in sets:
Although it is possible to buy wrenches individually, it makes good economic sense to buy full wrench sets, since a set is more cost effective than buying individual wrenches. Moreover, a set of wrenches, of any type, that contains 16 to 18 pieces will cover almost any size fastener you are likely to encounter during DIY jobs on your car of home.