Feeler Gauges & Strips

About Feeler Gauges & Strips

Feeler gauges and strips are precision measuring tools essential for checking gaps, clearances, and tolerances in mechanical assemblies across automotive, engineering, and industrial applications. These thin metal blades, manufactured to exact thicknesses typically from hardened steel or brass, allow technicians to measure spaces that conventional measuring tools cannot access. Whether setting spark plug gaps, measuring valve clearances, checking bearing tolerances, or adjusting machinery alignment, feeler gauges provide the accuracy demanded by professional work.

The selection at Tooled-Up.com includes metric and imperial gauge sets from trusted manufacturers including Sealey, Draper, Siegen, Facom, Starrett, and Faithfull. Available in various configurations from compact 10-blade sets for basic applications through to professional 36-blade combination sets, these precision instruments cater to automotive technicians, engineers, machinists, and maintenance professionals. Standard straight blade sets, angled gauges for restricted access, offset designs for awkward spaces, and dual-marked options displaying both metric and imperial measurements ensure maximum versatility across different workshop environments.

Modern feeler gauge sets are engineered for durability and convenience, with blades secured in protective holders that maintain organisation and prevent damage. Professional sets feature etched markings that resist wear over time, whilst combination sets include both steel and brass blades to prevent surface damage when working with soft metals or magnetic components. Specialist taper bore gauges are also available for measuring internal diameters and checking bore wear in cylinders and hydraulic components.

Jargon Buster

• Metric vs Imperial – Feeler gauges are available in metric measurements (typically 0.05mm to 1.00mm) or imperial measurements (usually 0.002" to 0.040"). Dual-marked sets display both measurement systems on each blade for workshops handling diverse equipment specifications.
• Blade Count – The number of individual gauge leaves in a set. Sets typically range from 10 to 36 blades, with higher blade counts providing more measurement options and finer increments for precise adjustment work.
• Offset/Angled Gauges – Feeler gauges with blades bent at 45° or 90° angles, designed to reach confined spaces or awkward locations where straight gauges cannot access, such as recessed engine components or deep machinery assemblies.
• Combination Sets (Steel/Brass) – Professional gauge sets containing both steel and brass blades. Brass blades are non-magnetic and softer, preventing scratches on precision surfaces and avoiding interference when working near magnetic fields or electronic ignition systems.
• Go/No-Go Gauging – A measurement technique where feeler gauges determine if a gap falls within acceptable tolerances. If one blade fits but the next size up doesn't, the gap meets specification requirements.
• Taper Bore Gauge – Specialist measuring tool with tapered blades used to check internal diameters and bore wear, particularly useful for assessing cylinder condition in engines and hydraulic equipment.

Who Uses Feeler Gauges & Strips?

Feeler gauges are indispensable precision tools across numerous trades and industries:

• Automotive Technicians – Setting spark plug gaps, measuring valve clearances, checking piston ring gaps, and adjusting points on classic vehicles
• HGV and Plant Mechanics – Maintaining diesel engines, adjusting injector clearances, and checking tolerances on heavy machinery
• Agricultural Engineers – Servicing tractors, combine harvesters, and farm equipment requiring precise clearance settings
• Motorcycle Mechanics – Adjusting valve shims, setting ignition timing, and measuring chain wear on motorbikes and scooters
• Machinists and CNC Operators – Checking machine tool alignment, measuring work holding parallelism, and setting up precision equipment
• Maintenance Engineers – Inspecting industrial machinery, checking bearing clearances, and measuring shaft alignments in factories
• Aircraft Maintenance Technicians – Measuring control surface gaps and checking tolerances on aviation components
• Marine Engineers – Servicing marine diesel engines and maintaining boat propulsion systems
• Quality Control Inspectors – Verifying manufacturing tolerances and ensuring components meet specifications
• DIY Enthusiasts – Maintaining classic cars, servicing lawnmowers, and undertaking precision home workshop projects

How to Choose the Right Feeler Gauges & Strips

Measurement System: Determine whether you need metric, imperial, or dual-marked gauges based on the equipment you work with. UK and European machinery typically uses metric measurements, whilst American vehicles and older British machinery may require imperial gauges. Dual-marked sets from brands like Sealey and Draper offer maximum flexibility for mixed workshop environments.

Blade Count and Range: Consider the variety of measurements you need. A 10-blade set suits occasional use and basic applications, whilst 20 to 26-blade sets provide better coverage for regular automotive work. Professional technicians working across multiple disciplines benefit from comprehensive 32 to 36-blade sets offering the finest increments and widest measurement range.

Blade Configuration: Standard straight gauges handle most applications, but angled or offset sets are essential if you regularly work in confined spaces such as deep within engine bays or industrial machinery. Many professionals keep both types in their toolkit for complete coverage.

Material Specification: Steel blades are durable and suitable for most applications, but combination sets with brass blades prevent scratching on precision-machined surfaces and avoid magnetic interference when working with electronic ignition systems or near sensitive equipment.

Build Quality: Professional-grade gauges from manufacturers like Draper, Facom, Sealey, and Starrett feature hardened steel construction with etched markings that remain legible throughout the tool's lifetime. Budget options may have printed markings that wear off with repeated use. Look for sets with robust holders that protect blades when not in use.

Brand Reputation: Established brands stocked at Tooled-Up are trusted by professional technicians for accuracy and consistency. Their gauges are manufactured to tight tolerances and maintain their dimensions over time, which is critical for precision measurement work.

Popular Accessories

• Digital Callipers and Micrometres – Complement feeler gauges for comprehensive measuring capabilities, useful for verifying gauge accuracy and measuring larger dimensions
• Dial Indicators – Work alongside feeler gauges for checking runout, flatness, and perpendicularity in precision engineering applications
• Spark Plug Gap Tools – Specialised gauges designed specifically for adjusting and measuring spark plug electrode gaps on automotive engines
• Engineers' Squares and Straight Edges – Used in conjunction with feeler gauges to check flatness and parallelism of machined surfaces
• Cleaning Cloths and Maintenance Sprays – Keep gauge blades clean and protected from corrosion to maintain accuracy and extend tool life
• Tool Storage Solutions – Dedicated gauge holders or toolbox organisers protect precision measuring instruments from workshop damage

Safety Information

Whilst feeler gauges are generally safe hand tools, observe these precautions for optimal safety and tool longevity:

• Always ensure engines and machinery are switched off and cooled down before measuring clearances to prevent burns or contact with moving parts
• Handle gauge blades carefully as thin metal strips can have sharp edges; inspect for burrs or damage that could cause cuts
• Never force gauge blades into gaps as this can bend or permanently deform the metal, compromising accuracy and potentially causing injury if blades snap
• When working on automotive systems, disconnect batteries before measuring near electrical components to prevent short circuits
• Store feeler gauges in their protective cases when not in use to prevent damage from workshop debris and to avoid creating sharp-edged trip hazards
• Keep gauge blades clean and lightly oiled to prevent rust, which can alter blade thickness and reduce measurement accuracy
• Wear appropriate PPE including safety glasses when working under vehicles or machinery, as measuring work often involves confined spaces where debris may fall

Frequently Asked Questions

What's the difference between metric and imperial feeler gauges?
Metric feeler gauges display measurements in millimetres (typically 0.05mm to 1.00mm), whilst imperial gauges use inches or thousandths of an inch (usually 0.002" to 0.040"). The choice depends on your equipment specifications – European and modern machinery generally uses metric, whilst American vehicles and older British machinery may require imperial. Dual-marked gauges display both systems for maximum versatility.

How many blades do I need in a feeler gauge set?
For basic automotive maintenance and occasional use, a 10 to 12-blade set provides adequate coverage. Regular mechanics and technicians benefit from 20 to 26-blade sets offering finer increments. Professional workshops handling diverse equipment should consider comprehensive 32 to 36-blade sets with both metric and imperial markings for complete measurement capability.

Can feeler gauges lose their accuracy over time?
Yes, feeler gauges can lose accuracy if bent, kinked, or corroded. Quality gauges from brands like Draper, Sealey, Facom, and Starrett are made from hardened steel to resist deformation, but rough handling or forcing blades into tight gaps can permanently bend them. Store gauges properly, keep them clean and lightly oiled, and replace any visibly damaged blades to maintain measurement accuracy.

What are offset or angled feeler gauges used for?
Offset and angled feeler gauges have blades bent at 45° or 90° angles, allowing access to recessed areas where straight gauges cannot reach. They're particularly useful for measuring valve clearances on engines with limited access, checking gaps behind pulleys, or working in confined machinery spaces. Many professional technicians keep both straight and angled sets in their toolkit.

Why do some feeler gauge sets include brass blades?
Brass blades serve two purposes: they're non-magnetic, preventing interference with electronic ignition systems and sensitive equipment, and they're softer than steel, reducing the risk of scratching precision-machined surfaces. Combination sets with both steel and brass blades offer versatility for different applications, with brass blades ideal for aluminium components and delicate finishes.