Spring Callipers

About Spring Callipers

Spring callipers are traditional precision measuring instruments essential for engineers, machinists, and metalworkers who need to transfer dimensions accurately in workshop environments. Available in two main types—inside spring callipers for measuring internal dimensions like bore diameters, and outside spring callipers for external measurements such as shaft diameters—these tools feature a simple spring-loaded design with an adjustment screw for precise setting. Unlike digital measuring instruments, spring callipers require no batteries and excel in harsh workshop conditions where cutting fluids, metal swarf, and dust might compromise electronic tools.

MyToolShed.co.uk stocks spring callipers from trusted manufacturers including Draper, Faithfull, Moore and Wright, and Sealey, offering various sizes to suit applications from delicate precision work to heavy engineering tasks. These comparative measuring tools transfer dimensions to rulers or micrometers for accurate readout, providing the tactile feedback and reliability that experienced tradespeople value for quality control checks and repetitive measurement tasks.

Applications

Spring callipers are used across numerous trades and industries:

• Machinists and Turner Operators: Measuring turned components, checking shaft diameters, and verifying bore sizes on lathes and milling machines
• Mechanical Fitters and Engineers: Assembly work, maintenance inspections, and quality control in engineering workshops
• Tool and Die Makers: Precision measurement when creating tooling, jigs, and fixtures
• Fabricators and Metalworkers: Measuring pipe diameters, tube wall thickness, and structural steel dimensions
• Maintenance Engineers: Inspecting wear on shafts, bearings, and mechanical components during planned maintenance
• Pattern Makers and Foundry Workers: Checking dimensions of patterns and castings during production
• Vintage Machinery Restorers: Measuring components on classic engines and equipment
• DIY Enthusiasts: Home workshop projects involving metal turning, model engineering, and precision fabrication

Choosing The Right Spring Callipers

Measurement Type: Determine whether you need inside callipers for internal measurements, outside callipers for external dimensions, or both. Most professional tradespeople keep matched pairs in their toolbox for comprehensive workpiece inspection.

Size Range: Select the leg span based on typical dimensions you measure. Common sizes include 75mm, 100mm, 150mm, 200mm, and 300mm maximum opening. A 150mm size offers excellent versatility for general engineering work, whilst smaller sizes suit delicate tasks and larger callipers handle substantial components.

Build Quality: Professional-grade spring callipers from Moore and Wright feature hardened steel construction with corrosion-resistant finishes for demanding workshop environments. Draper, Faithfull, and Sealey offer excellent value options suitable for general workshop use and DIY applications. MyToolShed.co.uk stocks quality options across all price points to suit both professional tradespeople and home users.

Adjustment Mechanism: Quality callipers feature smooth, fine-threaded adjustment screws with knurled nuts for easy grip, enabling precise dimensional setting even with oily fingers.

Frequently Asked Questions

What's the difference between inside and outside spring callipers?

Inside spring callipers have legs that curve outwards, designed specifically for measuring internal dimensions such as hole diameters and bore sizes. Outside spring callipers have legs that curve inwards to measure external dimensions like shaft diameters and material thickness. The leg geometry is optimised for each application—using the wrong type compromises accuracy and risks damaging the workpiece.

How accurate are spring callipers?

Spring callipers are comparative tools that transfer dimensions to be read on a separate rule or micrometer. Their accuracy depends on user skill and the precision of the reference scale used. In experienced hands, they reliably transfer measurements to within 0.1mm when used with quality micrometers, making them ideal for checking consistency across multiple components.

How do I maintain spring callipers?

Keep the pivot point and adjustment screw lightly oiled with engineering oil for smooth movement. Wipe the legs clean after use, particularly if exposed to cutting fluids or metal swarf. Store in a protective case to prevent damage to the points, and avoid dropping them as this can affect spring tension or bend the legs.