Spanners & Wrenches

Spanners are hand tools that in some instances are also known as 'wrenches'. Spanners have a variety of ways of gripping and turning fasteners, such as nuts and bolts, with some gripping the edges, whereas other spanners encapsulate the fastener from above.

Spanners are a standard hand tool in almost all DIYers and trades peoples tool boxes, with many opting for having a spanner set, so that a wide range of fasteners sizes can be tightened and untightened.

Frequently Asked Questions about Spanners & Wrenches

How do I choose the right spanner size for my project?

Spanner sizes correspond to the distance between their jaws or ring diameter, measured in metric or imperial units. We have a guide on bolt sizes, which is useful to ensure the correct spanner size is used on the corect bolt, which will help to prevent damage to the tool or fastener.

What is the difference between metric and imperial spanners?

The difference is simply the measurement type of the spanner, with metric spanners being sized in millimetres, whilst imperial spanners are measured in inches.

Can I use an adjustable spanner for all bolt sizes?

Yes, an adjustable spanner can fasten/unfasten any bolt size between its maximum and minimum jaw opening. Adjustable spanners do provide a weaker grip than fixed sized spanners though, which does increase the risk of rounding a fastener off, however because adjustable spanners can fasten a wide range of bolt sizes, they are a convenient spanner to have in a tool bag if an open end spanner set is not wanted.

What are ratcheting spanners and what advantages do they offer?

Ratcheting spanners have a mechanism allowing continuous turning without repositioning, making them faster and more convenient, especially in confined spaces. Essentially a nut or bolt can be fastened/unfastened without the ratcheting spanner ever losing contact with the fastener, with the ratcheting mechanism also making it easier to turn the fastener, which means less effort is required from the operator.

How should I maintain and store my spanners?

Wipe spanners clean after use, and add some tool oil to prevent rust forming on them. We would also recommend storing them in a tool box or rack to prevent them from getting damaged or lost.

Can spanners be used on damaged or rounded bolts?

Special spanners like flank drive or gripping spanners are designed to grip the sides of fasteners rather than the corners, making them useful for working on damaged or rounded bolts.

What are flare nut spanners and when are they used?

Flare nut spanners have a partially enclosed head, offering better grip on soft metal fittings like brake or fuel lines, which is why they are also known as 'brake wrenches'. They're used widely by mechanics, plumbers and HVAC technicians.

A Guide to Metric Bolt Sizes

Choosing the correct metric bolt size is essential in construction, engineering and DIY projects. Metric bolts, measured in millimetres, are widely used across industries for their precision and standardisation.

What Size Spanner Do You Need?

Spanners are a great addition to any toolbox, but which type should you use? Here is a guide to help you establish which spanner you need for your DIY project.

16 Types of Spanners and Their Uses

With so many different spanners available, how do you know which one to use? We’ve compiled a list so you can see what each spanner does and which you need.

Spanners Vs Wrenches: What’s The Difference?

Learn the key differences between spanners and wrenches in this guide from Heamar. Find out which tool fits your task – with real-world examples and expert picks.