You can buy individual feeler gauges in the UK at specific thicknesses, which is a cheap and convenient way of replacing a single blade if one should snap or become damaged. However, it is usual to start with a full set of them.
Below, we have listed some of the most common types, materials and models of feeler gauges. Most are available either as full sets or as individual blades.
Wire Type Feeler Gauges
A wire-type feeler gauge is a little different to the standard shim arrangement. Instead of featuring a series of graded metal leaves or blades, the wire feeler gauge instead has a series of rigid metal wires.
Again, these are calibrated to specific thicknesses and normally bent over at a right angle. Wire type feeler gauges are typically used for measuring spark plug gaps, so you might also see them referred to as spark plug gap gauges.
Blade Feeler Gauges
A blade feeler gauge is probably the most common type of gap gauge you will encounter when shopping for these tools online. They usually feature a range of graded flattened metal shims or leaves which are designed to fold in or out of a central case or sheath.
The blades can typically be fanned out from the central case to easily select and access the one you want to use. If a single strip gets damaged or breaks, you can buy an individual one to replace it at the same thickness.
Thin Feeler Gauges
All feeler gauges are somewhat thin. This is because the point of them is to fit into and measure gaps that are far too narrow for most other common measuring tools, such as tape measures.
It is relatively rare to find sets that include blades any thicker than around 5mm at the upper limit, although they do exist. Most people who buy feeler gauges for mechanical or engineering work are more concerned with measuring much smaller gaps. In this regard, thin feeler gauges can be graded down to thicknesses of just 0.02mm or less.
The measurements for individual blades might be given in either metric or imperial units - or in both. When shopping online for gap gauges in the UK, remember to check that your chosen product displays the right type of measurement units for your requirements.
Angled Feeler Gauges
Angled feeler gauges are ones whose tips are bent over at a slight angle to the rest of the blade. This can be handy for accessing harder to reach gaps, where it may not be possible to slide a standard gap gauge in straight enough to get a good reading on the width of the opening. They are also known as offset feeler gauges.
Feeler Gauge Sets
It is more common to start by buying a feeler gauge set, and then later to replace any blades that become damaged or broken one at a time. A sheaf of multiple blades or leaves enables you to test various strips of different thicknesses in the gap you are trying to measure. This typically makes it fairly easy to work out the size of the gap by a simple process of comparison and elimination.