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In this guide, learn all about various types of wrenches and how to use them on hex nuts and bolts. This guide also covers things to consider when purchasing wrenches.
Using A Wrench
A wrench is a common hand tool used to tighten or loosen nuts and bolts. The most common type of nuts and bolts that you see pictured are hex nuts and hex bolts. Every wrench has two parts: the head of the wrench is used to grip fasteners; the handle of the wrench is where you will hold the wrench when tightening or loosening fasteners. Fasteners refer to materials used as connecting devices like hex bolts, hex nuts, and hex screws.
The head of the wrench grips the fastener, allowing you to rotate it to tighten or loosen it. The handle of a wrench provides leverage that makes it easier to tighten or loosen a fastener. When using a wrench, use your dominant hand to hold the wrench near the end of the handle to achieve the greatest amount of leverage.
When choosing a wrench, choose one that is slightly larger than the diameter of the bolt head. While bolts are typically measured in inches, wrenches have two types of sizing:
Imperial or SAE, where the measurement is in fraction of inches like 1/4" and 9/16”
Metric, where the measurement is in whole millimeter figures like 10 mm or 8 mm
It's more common to find SAE sizing for wrenches in the United States where SAE sized fasteners are used. Other countries are more likely to use metric sizing for wrenches since they have metric sized fasteners. While some SAE and metric sizes may overlap, it's generally recommended to stick to SAE sized wrenches for SAE sized fasteners, and metric sized wrenches for metric sized fasteners.
Determining whether you're more likely to work with SAE sized fasteners or metric sized fasteners is very important. If a wrench is not the correct size or it is not properly placed on the fastener, the wrench can slip off the nut or bolt; this is called wrench slippage. To avoid wrench slippage, make sure your wrench is the correct size and in proper contact with the bolt or nut. Make sure to pull the wrench at a 90-degree angle to the fastener and towards you to reduce risk of injury.
To tighten a nut or bolt, turn the wrench clockwise. To loosen a nut or bolt with an open wrench, turn the wrench counterclockwise. Remember “Righty tighty, lefty loosey.” In some cases, you will not be able to rotate the wrench in a full circle. If this happens, you must reset the wrench jaws after each turn.
When you try to loosen a nut or a bolt, the nut and bolt may spin at the same time. If this happens, the nut will not loosen even as you rotate the wrench. To prevent the nut and bolt from spinning at the same time, we use a technique called a holdback. A holdback is when you grip the nut with a wrench, and the bolt with another wrench. One wrench prevents the bolt from rotating, and the other wrench is used to loosen the nut.
Although it seems like a straightforward tool, it's important to keep in mind how to minimize injuries when using any wrench. Before using a wrench, inspect the wrench for damage. Do not use a bent, cracked or damaged wrench. Do not use a wrench on moving machinery or to strike objects. If you need to strike an object, use a hammer. Do not strike a wrench with a hammer to gain more force.
Types of Wrenches
When picking the right tool for the job or a wrench set to purchase, there are many different wrenches to consider. Each type of wrench is a specialized tool designed for specific tasks.
Open Wrench
Open wrenches have a U-shaped head on both sides of the handle. The two heads are different sizes, allowing you to work on multiple sized nuts or bolts with one wrench. An open end wrench is great for reaching nuts or bolts in hard to reach spaces, but have a higher chance of wrench slippage.
Start by identifying the correct size open end wrench for the nut or bolt. Then, insert the nut or bolt head deep into the U of the jaws of the open end wrench. Make sure that the jaws of the wrench are in solid contact with the head of the bolt.
Box Wrench
A box wrench looks similar to an open end wrench, but has ring-shaped heads on both sides of the handle instead. The two heads are different sizes that let you work on multiple sized nuts or bolts with one wrench.
Box wrenches provide more contact with the bolt head than an open wrench. More contact between the box wrench and the bolt head increases the wrench’s grip on the fastener. Additional grip reduces the chance of wrench slippage.
To use a box wrench, start by identifying the correct size box end wrench for the nut or bolt. Insert the nut or bolt head securely into the box head of the wrench.
Combination Wrench
To receive the benefits of both the box and open wrenches, use a combination wrench. A combination wrench combines an open wrench and a box wrench, having one head that is U-shaped and another head that is ring shaped. For this reason, combination wrenches can be a very convenient tool. You can use the box end of a combination wrench to loosen a very tight bolt or the open end of a combination wrench to reach nuts in hard to reach areas. The heads on a combination wrench are the same size.
Keep in mind that combination wrenches typically come in combination wrench sets with a variety of different sizes. Because of this, combination wrenches may end up being a more expensive option. In certain instances, some find only one end of a combination wrench useful and would rather purchase just an open wrench or box wrench. Consider whether or not a combination wrench is the best tool for jobs in your field before purchasing a combination wrench set. If you're skeptical about using a combination wrench, you may find crescent/adjustable wrenches a better alternative.
Crescent/Adjustable Wrench
A crescent wrench, or adjustable wrench, has an adjustable jaw size. The adjustable jaw allows you to use the adjustable wrench on different sizes of nuts and bolts. This way, you do not need to find a specific wrench for a bolt or nut.
An adjustable wrench has a “warm screw” just above the handle. Turn the warm screw to increase or decrease the width of the jaws. Start by making sure that your adjustable wrench jaws can fit the nut or bolt you are working on. Twist the screw until the jaws are slightly larger than the nut. Place the nut inside the jaws of the crescent wrench.
Once the nut is inside the jaws, turn the warm screw to slowly tighten the jaws of the adjustable wrench. Once the jaw is tight around the nut, you can begin to tighten or loosen the nut. When you rotate the wrench, it is important that the force is directed into the fixed jaw. To do this, the fixed jaw should always be on the opposite side of the turning direction.
Socket Wrench & Ratchet Wrench
A socket wrench has a handle, a head with a square extension coming out of the head, and a socket. Sockets allow you grip different sized nuts or bolts. The socket locks onto the square extension on the wrench head.
The socket functions similarly to a box end wrench. The nut or bolt head will fit into the hollow opening of the socket. However, because you can use a ratchet to change sockets for different sized nuts, socket wrenches useful in any situation.
While they're technically different, you may hear a socket wrench be referred to as a ratcheting socket wrench or ratchet wrench. Unlike socket wrenches, ratchet wrenches have a a fixed square drive size with specialized sockets instead of interchangeable sockets. However, both socket wrenches and ratchet wrenches have a ratcheting mechanism. Thus, you may hear the terms socket wrenches and ratchet wrenches be used interchangeably on the field.
Ratcheting mechanisms make it easier to quickly tighten or loosen nuts compared to other wrenches. With a socket wrench, you don't need to reset the wrenches head position with each pull. As you rotate the wrench back to the starting position, the ratchet doesn't turn the nut or bolt. The ratchet only turns the nut or bolt when you are rotating the wrench in a specific direction.
A socket wrench can loosen or tighten based on its knob setting. To change the direction in which the socket turns, flip the knob on the head of the wrench. If the knob is switched to one setting the socket wrench will only grip the nut when you rotate the wrench clockwise. If the knob is switched to the other setting, the wrench will only grip the nut when you rotate the wrench counterclockwise.
To change a socket, press the quick release button on the back of the socket wrench. Pull the socket away from the head of the wrench and the socket will come off. To add a new socket, press the quick release button on the back of the head of the wrench. Slide the socket onto the square extension of the wrench. Release the quick release button when the socket is fully on the wrench. Pull the socket to confirm it is secure.
To use a socket wrench, start by attaching the correct size socket for the nut or bolt you are working on. Set the direction of the knob on the socket wrench to tighten or loosen using the ratchet. Press the socket onto the head of the nut so there is full contact. When you cannot rotate the wrench further using the ratchet, move the handle back to the starting position. Rotate the wrench again.
Oftentimes when purchasing socket wrenches, you may purchase a ratcheting wrench set alongside a socket set. A socket set provides the interchangeable sockets for your socket wrench. While there are various sizes of tool accessories within a socket set, no one socket set may provide everything you need since there are so many different sizes and shapes of nuts and bolts. It's important to consider what kinds of fasteners you're likely to encounter in your field before purchasing a socket set to ensure that you find the right socket set for your job.
A socket set can come in a variety of types or sizes. For example, a standard socket set includes the most common socket sizes and parts while an impact socket set is curated to be used alongside power tools. You may also find a socket set described by size (ex: small socket set or 1/2 inch socket set).
Allen Wrench
An Allen wrench has an L-shaped body with a hexagonal head at each end and is used when tightening and loosening bolts with hexagon shaped sockets on their heads. You can insert either end of the Allen wrench into a hexagonal head, but each end has unique advantages.
If you insert the Allen wrench so that the wrench is vertical, you will have less leverage, meaning you will need to work harder to rotate the wrench. However, this positioning can make it easier to reach hard to reach areas. You can gain leverage by inserting the Allen wrench at a 90 degree angle to the nut. This additional leverage in this position makes it easier to loosen very tight bolts. In general, the long lever position is typically the best one to use.
Pipe Wrench
A pipe wrench is designed to be used on soft piping, like black pipe. The pipe wrench has an adjustable jaw that lets you work on a variety of pipe sizes. The jaws of a pipe wrench also have sharp teeth which give it a better grip on pipes.
The pipe wrench has four parts:
Handle
Adjustable nut - a rotating dial that you twist to adjust the size of the adjustable jaw
Fixed jaw - the jaw that is fixed into one position
Adjustable jaw - the jaw that moves up and down as you rotate the adjustable nut
The adjustable jaw also has a rocker built into the jaw. The rocker allows the fixed jaw to hook onto pipe. It also allows you to easily reposition the jaw.
Pipe wrenches are longer than other wrench types to provide more leverage. To use a pipe wrench, start by rotating the adjustment nut until the pipe jaws are slightly larger than the pipe. Place the pipe in between the jaws. The pipe should not be touching the back of the jaw.
Rotate the adjustment nut until the pipe jaws are lightly biting into the soft pipe. When using a pipe wrench, you want the force to go into the fixed jaw. To do this, the opening in the jaws should be facing in the direction you will rotate the wrench. If you try to rotate the pipe wrench in the wrong direction, the rocker will unhook the wrench.
Once you have rotated the pipe, you can bring the pipe back to the starting position. Similar to the socket wrench, the adjustable jaw on the pipe wrench only pulls in one direction. This allows you to make multiple turns of the wrench without having to remove the wrench from the piping.
Once the pipe is loosened, remove the pipe wrench from the pipe. Press down on the adjustment nut and the adjustable jaw will loosen from the pipe. Pull the pipe wrench away from the pipe.
When you are using a pipe wrench, you must be careful what material you place the wrench on. The teeth of the pipe wrench can damage softer materials like brass. The teeth can also damage pipe threading, nuts, bolts, and other fasteners.
Using two pipe wrenches might be necessary when connecting two free moving pieces of pipe. One wrench is used to hold one piece of piping in place. The other wrench is used to tighten or loosen the other pipe. To tighten the two pipes together, move the pipe wrench that is closest to you clockwise and the other wrench counterclockwise. To loosen the two pipes, move the pipe wrench that is closest to you counterclockwise and the other wrench clockwise.
When choosing a pipe wrench, pick one that is suitable for the pipe you are working with. A pipe wrench that is too large is harder to turn and can damage smaller pipe. A pipe wrench that is too small will not have the grip to turn larger pipes.
Specialized Types of Wrenches
Breaker Bar
A breaker bar is a long bar that attaches to a socket wrench to give you more leverage. They are used in the same way as a socket wrench. A breaker bar should be used when nuts are difficult to remove.
Torque Wrench
Each type of bolt and nut have specific torque requirements. Torque refers to the amount of force used to make an object rotate on an axis. Applying too much torque can damage the fastener. Applying too little torque weakens the fastener.
A torque wrench is a precision tool that allows you to adjust the torque you are applying to a bolt. A torque wrench functions in a similar way to a socket wrench. The torque wrench has several parts:
Head
Socket
Rotating handle
Measurement marks
Nut
The nut on the bottom of the handle prevents the handle from moving. If the nut is loose, you can rotate the handle. Rotating the handle to the right will move the handle up the shaft of the torque wrench.
As the handle moves up the torque wrench, the wrench is set to a higher level of torque. You can see what torque the wrench is set to by looking at the top of the handle and the gauge marks.
To use a torque wrench, start by setting the wrench to the required torque. Loosen the nut at the bottom of the handle. Rotate the handle of the wrench until the handle is lined up with the correct measurement mark. Set the socket size of the torque wrench to the size of the nut you are working on. Press the torque wrench onto the nut. Turn the wrench clockwise to tighten the nut. Turn the wrench counterclockwise to loosen the nut. Continue rotating the wrench until the nut is loose or tight. Once you finish, set the torque wrench to its lowest measurement.
A torque wrench is best used when you don’t want to over tighten a bolt. They are commonly used when working on engines. An over tightened bolt can cause an engine to crack.
A torque wrench can measure force in multiple units such as:
Pound-foot (lb-ft)
Pound-inch (lb-in)
Newton-meter (Nm)
Service Wrench
Service wrenches, or pump wrenches, are lighter wrenches that are used in low force jobs. They are easy to carry and provide delicate force for certain jobs.
Service wrenches are commonly used in the HVAC industry. They are great for...
Opening and closing gas tanks
Adjusting thermostat valves
Opening and Closing valves
Purchasing Wrenches - Understanding Wrench Sets
When selecting the right wrenches for your tool kit, it's important to consider the specific needs of your job and the types of fasteners you'll encounter most frequently. A well-chosen wrench set can be an invaluable addition to any mechanic's or DIY enthusiast's tool collection.
When purchasing a wrench set, consider the following factors:
Variety: A good wrench set should include a combination of different types of wrenches. Look for a wrench set that offers a combination of open end, box end, and adjustable wrenches, as these tend to be the most common types of wrenches for any job.
Size range: Ensure the wrench set covers the sizes you'll need most often and consider if you are more likely to work with SAE sized fasteners or metric sized fasteners. Most wrench sets focus on one type of sizing (SAE wrench set or metric wrench set). A comprehensive wrench set typically includes sizes from 1/4 inch to 1 inch for SAE measurements, and 8 mm to 19 mm for metric.
Material quality: The durability of your wrench set is crucial. Look for wrench sets made from high-quality materials like chrome vanadium steel, which offers strength and corrosion resistance.
Warranty: A good warranty can protect your investment. Some manufacturers offer lifetime warranties on their wrench set.
Specialty needs: If you work in a specific field, you might need a specialized wrench set. For example, plumbers might prioritize a wrench set that includes pipe wrenches.
Budget: Wrench sets can vary widely in price. While it's tempting to go for the cheapest option, investing in a quality wrench set can save you money in the long run. Options with free delivery may be something to consider if staying within a budget is important.
Completeness: Some wrench sets include additional tools like socket sets or screwdrivers. Consider what combination of tool add-ons are necessary for your needs.
Frequency of use: If you'll be using these tools frequently, it's worth investing in a higher-quality set. For occasional use, a mid-range wrench set might suffice.
Whether you are in a trade field or are looking to DIY something, the right wrench set for you depends on your specific needs and preferences. Take the time to compare different options and read reviews before making your purchase. A well-chosen wrench set will serve you well for years to come, making your work easier and more efficient. The right combination of tools for the job not only makes your work easier but also ensures better results and safety.