How to Tighten Bolts and Nuts


Nuts and bolts are some of the most common fastener types used in all sorts of mechanical applications. They’re used to hold two or more objects together, with the nut on one end and the bolt on the other, and the fastened material sandwiched in between.

Learning how to tighten nuts and bolts is typically fairly straightforward, but can sometimes be complicated by things like tight fastening locations, stripped threads, inadequate tools, and more.

nut and bolt with washers
Typical nut and bolt with washers. [Image source]
Let’s take a look at how to tighten bolts and nuts, as well as tips and tricks to solve common issues you might run into.

What Tools are Used to Tighten Bolts and Nuts?

Wrenches

The most common tools used to tighten nuts and bolts by far are wrenches. There are several different types of wrenches out there, including the adjustable crescent wrench, the combination wrench, ratcheting wrenches, and even specialty wrenches like basin wrenches and strap wrenches.

Wrenches are the ideal tool for this task, although you can also use things like pliers in a pinch.

When using a wrench to tighten a nut and bolt, you’ll need a pair of two wrenches – one to hold the nut and one to hold the bolt. You can also use a combination of a wrench and a pair of pliers, or one open-ended wrench to hold the nut and a ratchet to tighten the nut.

using a ratcheting wrench to tighten a lag bolt
Tightening a lag bolt with a ratcheting wrench.

Impact Drivers

Impact drivers look similar to power drills, but operate slightly differently in that they create short bursts of rotational force that can drive through thick, tough materials with ease. This makes them ideal for driving large fasteners, as well as tightening bolts.

Impact drivers make short work of tightening nuts and bolts, making them an ideal tool when you have many nuts to fasten. If you’re working on a project with a lot of bolts to fasten, then the cost of purchasing an impact driver often makes sense. They’re fairly inexpensive nowadays and are highly useful for driving regular fasteners like screws and lag bolts.

Impact Wrenches

Impact wrenches are similar to impact drivers, but are beefed-up versions offering increased levels of force and torque. They also use rapid concussive rotary force to rotate the shaft of the tool, so function in essentially the same manner.

Impact wrenches are often used in automotive situations, and typically provide double the amount of torque as an impact driver.

How to Tighten a Nut and Bolt?

Tightening a nut and bolt can be somewhat self-explanatory, but there are some intricacies to be aware of.

Using a Wrench

Before threading the bolt through the hole, clear out the inside of the hole of any debris. If the hole is threaded you’ll want to check that the threads on the bolt match the threads in the hole.

If the hole has no threads, then insert the bolt and check to see that the bolt fits snugly in the hole.

Then with the bolt inserted into the hole, twist the nut onto the threaded portion of the bolt that’s poking out. Make sure you install the nut in the right direction, typically it will only thread in one direction and won’t screw smoothly the other way.

tightening nut with wrench
Tightening a nut with a closed-end wrench. [Image source]
Hand tighten it until it is no longer possible to do so by hand.

At this point, you’ll need to break out the wrenches to continue the tightening process. Slide one wrench over the nut and another over the bolt. If you’re using a crescent wrench, adjust it so that it fits properly over the nut and/or bolt. If using a ratcheting wrench, use the ratcheting portion over the nut, not the bolt.

Also, some bolt heads will have a hex head, so you’ll need a hex key to hold them steady instead of a second wrench.

Tighten the nut clockwise until you’re no longer able to do so without stressing. Then give it one more quarter-turn and call it a day.

With an Impact Driver

If you’ll be using an impact driver to tighten your nut and bolt, then complete the following steps:

  • Make sure the bolt is threaded cleanly through the hole.
  • Just like when you’re tightening a nut with a wrench, but reversed. You’ll need to keep the nut in a fixed stationary position in order to fasten the bolt. Otherwise, the bolt will simply spin freely and won’t tighten at all.
  • Next, insert the right-sized socket bit into your impact driver, and fit the socket over the bolt head. Ensure the entire bolt head is inside the socket, and also that the impact driver is set in the fastening and not unfastening setting.
  • Then, with the nut fixed in place with one hand, slowly fasten the bolt into place. Be careful not to overtighten the bolt – which is actually pretty easy to do with an impact driver due to their power.

What to Use if You Don’t have a Wrench?

If you find yourself in a situation where you don’t have a wrench and need to fasten a bolt – don’t despair! There are several methods of getting the job done in a pinch.

Method 1: Zip Tie

One of the best methods of tightening a nut and bolt in a pinch is by using a couple of regular old zip ties. Wrap a zip tie around both the bolt end and the nut, and then rotate the nut in a clockwise direction until the nut is completely fastened.

Method 2: Another Nut and Bolt

This is a clever method of tightening a nut and bolt, but if you have a second nut and bolt lying around, you can actually use it to tighten your existing one.

To accomplish this, simply thread a nut onto a bolt and then tighten it until it reaches the width of the bolt you want to fasten. Tighten your makeshift wrench until the nut is gripped tightly and then you can turn your nut until it’s fastened.

You may need to build a second nut and bolt wrench to hold the bolt head in place while you’re doing this if you don’t have a pair of pliers or something similar lying around.

Method 3: Coins & Large Wrench

If you happen to already have a large wrench lying around but it’s too big to fit the nut, then this method will work perfectly for you. Simply insert as many coins as needed between the wrench and the nut until it’s tightly sandwiched in place.

Then, tighten the nut as you would with any other wrench – until the nut is completely fastened.


Denis Gardner

I've loved tinkering and fixing things for as long as I can remember. So, naturally, I gravitated towards DIY and home improvement when I bought my first home. Nowadays you can find me writing about my passions or messing around with my newest tool!

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