How to use a wrench

Every wrench is nailed to a wood plank using nails, ranging from smallest-largest.

I never thought that I could use a wrench wrong. After several rounded bolts through my time, I googled “How to use a wrench” with several interesting results telling me how I had been wrong all my life. In this article, we will talk about the regular wrench, with one open, and one closed end.

Oh, and a TL;DR can be found at the bottom.

Basics

But lets start out with the basics. A wrench is used to apply more torque to a bolt or nut, than you could do with your bare hands. Always make sure that your wrench is fully seated on the bolt or nut before applying torque.

Push or pull?

I always pull wherever possible. This gives you more control of the operating environment, while pushing could lead to bleeding knuckles. Ask me how I know. The explanation is that pushing puts more a explosive force onto the wrench, and makes you unstable once the bolt breaks loose, or the wrench slips. Pulling is easier to control.

Do I use the open, or the closed end?

I had to think about this one for a while, but I had the theory that the closed end of the wrench would be in contact evenly over the bolt or nut, while the open end would only have contact with around half. My earlier experiences was that the open end would give away, and strip tight bolts more easily than the closed end. This was only my memory though, and further research was done.

In the book “I-Car Professional Automotive Collision Repair”, by James E. Duffy, 1995. The following was stated:

An open end wrench has three-sided jaws on both ends. This type of wrench is good if the bolt or nut is not very tight. The open jaws are weak. If a bolt is extremely tight, the open end wrench will bend or flex outwards and strip the bolt head”.

Get your copy here https://www.amazon.com/I-Car-Professional-Automotive-Collision-Repair/dp/0766813983

So, the conclusion is to use the closed end wherever possible, in order to avoid stripping bolt heads.

A photo showing the difference on a wrenches open, and closed end on a nut. The closed end has less surface contact than the closed end.
Seen in this photo is the difference between the open and closed end. The open end on the left has less surface contact, while the closed end on the right touches every single corner of the nut spreading the torque evenly.

Open end

The open end has more information to it than you would believe. First of all, the open end usually has an angle. This comes in handy when working in confined spaces where you are unable to get a second grip on the bolt, and you can turn the wrench around to get a better grip.

As the open end is somewhat angled, one way is also better than the other to make the bolt less prone to slipping. This can be seen in the photo below.

A photo showing how to correctly use the open end on a wrench.
The right photo shows the correct way, and is less prone to slip than the left photo.

12 sided and 6 sided closed end wrench

You might also have seen that some wrenches have a 6 pointed closed end, instead of a 12 point. The advantage found within a 12 point closed end is that you can fit the wrench on the bolt using a lot less movement than 6 point end. The 12 point will fit on a bolt in 12 different ways, with 30 degress between each, while the 6 point will fit in 6 different positions with 60 degrees between.
This is a photo of a 6 point vs a 12 point socket. Notice the difference in surface contact between the two.

However, the 6 point has the advantage of full surface contact to the bolt, while the 12 point essentially only has half . This allows more torque to be applied by the 6 point wrench, and should be used on tightened down bolts where the 12 point potentially could strip the heads.

A photo showing a 6 point, and a 12 point ratchet, with a nut inserted in both. The 6 point has 100% surface contact, while the 12 point only has 50% surface contact with the nut.
Seen on the left is a 6 point ratchet with 100% surface contact. The 12 point on the right can be seen with around half the surface contact, making it more prone to slip and strip the head.

Length of wrench

A short wrench will prove useful in tight areas, but will apply less torque than a long wrench. This essentially means that you might not be able to loosen some bolts and nuts with the short wrench. Applying enough torque to might also be a problem. Having a short, and a long one often proves useful.

Two 13mm wrenches, with different lenghts. The longer one can apply more torque, while the smaller one can be used in tighter areas.
This picture shows two 13mm wrenches, with different lenghts. The longer one can apply more torque, while the smaller one can be used in tighter areas.

The wrench has a curve

Yes, you probably have noticed that some wrenches are curved, or bent. I believe this simply is to get a grip on the wrench, while avoiding hurting you and your knuckles.
Seen here is the wrench being hold flat down on a plank to display how it is curved. This allows you to wrench without hurting your knuckles on the surface.

The wrench is placed on a flat surface in order to showcase how it is bent, allowing to wrench without hurting your knuckles.
An image showing how a wrench is bent.

Using other tools together with a wrench

Using other tools together with the wrench can be done. Forexample a pipe on top of the wrench to create a “Cheater bar”. This allows you to apply more force to the bolt or nut, but has the disadvantage of giving you less control.

Combining tools can be dangerous, and always make sure that safety is your number one priority. 

What sizes exists, and which ones do I need?

You have wrenches based on the metric system, and the US that uses inches. You buy the wrenches needed for your application. I mostly work on BMWs, meaning that I need metric wrenches only. However, american cars or motorcycles would need wrenches that uses inches. The sizes I have range from 6mm-19mm, but I also have a 22mm and a 32mm that are used on special occations.

Nearly every auto shop sells wrenches. My experience is that sets of wrenches ranging from small to large are sold at a cheaper price than buying individuals.

TL;DR

-Used for tighetning/loosening bolts and nuts.
-Use closed end if needed on tight bolts to avoid stripping them, and preferrably 6 pointed if necessary.
-Pull, not push.
-More length = more torque
-Metric and inches
-Can be bought at almost every auto shop

Comments?

– Do you agree with what I have written? I would LOVE your thoughts on the best way to use a wrench, and how this differs from mine.
– Wrenches can be used in many ways, such as combining two for more torque. What is your special trick?

Synonyms

Spanner, wrench

Disclaimer

Everything written is based off my experiences from having used wrenches for 10 years, together with some literature written by professionals. I am simply trying to give others information and advice, and I will not claim that everything I write is 100% correct.

Everyone has their own preferred method while using wrenches, which is what works best for that person. 

 

 

Author: Jehans Jr Storvik

A website with information on how to use tools, and do mechanic work in general with the main focus on cars. This blog is written by a 24 year old computer programmer and amateur mechanic. I have worked on cars since the age of 16, and I learned everything from scratch by myself working on 1990-2000 BMWs. I started with simple operations, and these days I can do engine swaps/rebuilds, suspension overhaul, and building amateur race cars with forced induction. I am a 24 year old computer programmer, and amateur mechanic from Norway. My interest for mechanics started as a child when I disassembled our familys lawnmower to study how it worked. I never got it working again. As I turned 15, I started working on two stroke dirtbikes, and I found the tuning part especially fun. However, a manual 94' BMW E36 325i acquired at the age of 18 turned this interest into a passion. I have since attempted to do all maintenance and mechanical operations myself, to gain further knowledge. These days I am able to do nearly all maintenance by myself, and other things such as: -Engine swaps -Tuning using forced induction, or cam swaps. -Suspension overhauls -Basic welding and cutting. -Basic wire and electric knowledge. -Basic ECU tuning

3 thoughts on “How to use a wrench”

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