Dial Indicators

About Dial Indicators

Dial indicators are precision measuring instruments essential for engineering, machining, and quality control work where accuracy matters. These mechanical or digital gauges measure small linear distances with exceptional precision, typically reading down to 0.01mm or 0.001" increments. They work by converting the linear movement of a contact point into a rotary movement displayed on a calibrated dial face or digital screen, allowing tradespeople to detect minute variations in dimensions, runout, surface flatness, and concentricity.

Our range includes metric and imperial dial indicators, dial test indicator kits, bore gauge sets with interchangeable anvils, and complete sets with magnetic bases for versatile positioning. Whether you're checking component tolerances on a lathe, measuring bearing clearances, setting up CNC machinery, or inspecting manufactured parts for quality assurance, these tools provide the repeatable accuracy required for professional engineering work. Available from trusted brands including Draper, Sealey, and Facom, our dial indicators meet the demanding standards of British manufacturing and precision engineering.

Modern digital dial gauges offer additional features such as dual metric/imperial readings, data output capabilities, and easier readability in poor lighting conditions, whilst traditional analogue dial indicators remain popular for their reliability, no-battery operation, and tactile feedback that experienced engineers prefer.

Jargon Buster

• Resolution: The smallest measurement increment the indicator can display, typically 0.01mm (10 microns) for standard dial indicators or 0.001mm (1 micron) for precision models. This determines how finely you can measure dimensional variations.
• Contact Point: The movable probe or tip that touches the workpiece being measured. Available in various configurations including spherical, flat, and pointed designs for different measuring applications.
• Plunger Travel: The total distance the contact point can move in and out, typically ranging from 10mm to 50mm depending on the model. This determines the range of measurements possible without repositioning.
• Magnetic Base: An adjustable mounting system with a powerful magnetic foot that securely attaches the dial indicator to ferrous surfaces such as machine tables, allowing hands-free measurement with precise positioning.
• Bore Gauge: A specialised dial indicator configuration designed specifically for measuring internal diameters of holes, cylinders, and bores. Features interchangeable measuring heads for different size ranges.
• Runout: The measurement of how much a surface varies from being perfectly circular or flat as it rotates. Dial indicators excel at detecting runout on shafts, spindles, and rotating components.

Who Uses Dial Indicators?

Dial indicators are essential tools for a wide range of precision trades and applications:

• Machinists and CNC Operators: Setting up workpieces, checking component tolerances, and ensuring machine accuracy on lathes, mills, and machining centres
• Mechanical Engineers: Quality control inspections, dimensional verification, and prototype testing in manufacturing environments
• Automotive Technicians: Measuring crankshaft runout, checking brake disc flatness, verifying engine component tolerances, and diagnostic work
• Toolmakers and Die Makers: Precision tool setup, mould alignment, and quality inspection of manufactured tooling
• Metrology Technicians: Professional inspection and measurement in quality assurance laboratories and manufacturing facilities
• Maintenance Engineers: Checking bearing clearances, shaft alignment, and machine calibration during preventative maintenance
• Fabricators and Welders: Verifying flatness and alignment of fabricated assemblies before and after welding
• Precision DIY Enthusiasts: Model engineering, home workshop machining projects, and equipment restoration requiring accurate measurements

How to Choose the Right Dial Indicators

Analogue vs Digital: Traditional dial indicators offer robust mechanical simplicity with no batteries required and excellent tactile feedback, making them ideal for workshop environments. Digital models provide easier reading, dual unit displays, data logging capabilities, and better visibility, suited to quality control and inspection work.

Resolution and Accuracy: Standard dial indicators offer 0.01mm resolution suitable for most machining and engineering applications. High-precision models with 0.001mm resolution are necessary for metrology work and extremely tight tolerances. Consider what accuracy your work genuinely requires - higher precision costs more and may be unnecessarily sensitive for general workshop use.

Measurement Range: Choose plunger travel based on your typical applications. Shorter travel (10mm) provides greater rigidity and accuracy for small variations, whilst longer travel (25-50mm) offers versatility for larger dimensional checks without repositioning.

Mounting Requirements: Complete kits with magnetic bases and adjustable arms provide maximum versatility for various measuring positions. Stand-alone indicators work when you already have mounting equipment or need compact storage. Bore gauge sets include specialised mounting for internal measurement work.

Metric vs Imperial: UK engineering predominantly uses metric measurements, but some industries and older machinery require imperial readings. Dual-reading digital models eliminate conversion calculations, whilst analogue users should match the scale to their primary work requirements.

Brand Quality: Draper Expert and Facom represent professional-grade accuracy suitable for critical engineering applications. Sealey offers excellent value for workshop and automotive use. For metrology and inspection work requiring certified accuracy, consider models supplied with calibration certificates traceable to national standards.

Popular Accessories

• Magnetic Bases with Adjustable Arms: Essential for hands-free operation, these versatile mounting systems position indicators precisely against machine tables, surface plates, or any ferrous surface. Articulating arms allow infinite positioning angles.
• Interchangeable Contact Points: Different tip shapes including spherical, flat, pointed, and extended reach designs suit various measuring scenarios and workpiece geometries.
• Storage Cases: Protective carrying cases prevent damage to precision instruments and keep complete kits organised with foam inserts for each component.
• Extension Rods and Clamps: Increase measuring reach and provide additional mounting options for difficult-to-access locations.
• Test Indicator Holders: Precision mounting brackets and dovetail attachments for installing indicators on machine tool carriages and inspection equipment.
• Calibration Standards: Gauge blocks and setting masters for verifying indicator accuracy and maintaining measurement traceability.

Safety Information

Whilst dial indicators themselves present minimal safety risks, observe these important precautions:

• Always secure workpieces and ensure machinery is properly stopped before taking measurements to prevent unexpected movement that could damage the indicator or cause injury
• Be cautious when using magnetic bases near rotating machinery - ensure the base cannot be dislodged by swarf, coolant, or vibration
• Wear appropriate PPE including safety glasses when working around machining operations, even during measurement tasks
• Ensure indicators are properly mounted with stable support before applying contact pressure to avoid sudden slipping or dropping
• Store precision instruments away from extreme temperatures, moisture, and magnetic fields that could affect accuracy
• Never force the plunger beyond its travel limits as this can permanently damage the internal mechanism and compromise accuracy
• Follow HSE guidelines for manual handling when positioning heavy magnetic bases and mounting equipment

Frequently Asked Questions

What's the difference between a dial indicator and a dial test indicator?

A standard dial indicator measures linear movement along a single axis with the plunger moving perpendicular to the dial face. A dial test indicator (DTI) has a lever arm with the contact point at right angles to the dial, making it better suited for measuring surface runout and positioning work on machine tools. Both serve different but complementary measurement purposes.

How often should dial indicators be calibrated?

For professional metrology and quality control work requiring traceability, annual calibration against certified standards is recommended. In general workshop use, verify accuracy periodically using gauge blocks or precision references, and recalibrate whenever you suspect damage or after heavy use. Keep records of calibration dates, especially if working to ISO 9001 or similar quality standards.

Can I use metric dial indicators for imperial measurements?

Whilst mathematically possible using conversion factors, this introduces calculation errors and defeats the precision purpose of dial indicators. For regular imperial work, invest in a dedicated imperial gauge or choose a digital model with switchable metric/imperial displays for convenient unit conversion without accuracy loss.

Why does my dial indicator reading change when I remove contact pressure?

This typically indicates either insufficient preload (the indicator should be set with some spring compression), movement in the magnetic base or mounting, or flex in the measuring setup. Ensure rigid mounting, proper preload of approximately 1mm travel from the rest position, and that workpieces are securely held. Thermal expansion can also cause readings to drift on precision measurements.

What maintenance do dial indicators require?

Keep the plunger and contact point clean and lightly lubricated with precision instrument oil. Avoid getting swarf, coolant, or abrasive dust inside the mechanism. Store in protective cases away from magnetic fields and extreme temperatures. Never disassemble the internal mechanism as this requires specialist tools and will void calibration. If dropped or damaged, have professionally inspected before relying on measurements for critical work.