Mitutoyo 511-726-20 Dial Bore Gauge

Technical Overview

Metric dial bore gauge with 250-400mm range, 0.001mm graduation, and ±2µm accuracy. Features carbide contact points and 50% thermal isolation grip design.

Key Features

Wide-range measurement from 250 mm to 400 mm utilizing interchangeable anvils and fine-increment spacers.
Highly reliable Mitutoyo 2109AB-10 dial indicator included as standard to read to 0.001 mm increments.
Carbide-tipped contact points and anvils provide outstanding durability and long-term wear resistance.
Specialized hollow-structured handle reduces thermal transmission from the operator's hand to the gauge body by 50%.
Self-centering guide bridge ensures rapid alignment and stable positioning inside the cylinder bore.
Supplied as a comprehensive kit inside a fitted protective carrying case.

Technical Specification Matrix

Parameter	Value
Measuring Range	250 - 400 mm
Graduation	0.001 mm
Accuracy	±2 µm
Repeatability	0.5 µm
Indication Stability / Adjacent Error	1 µm
Measuring Depth (Probe Depth)	250 mm
Measuring Force	6 N or less
Stroke of Contact Point	1.6 mm
Stem Diameter	8 mm
Dial Indicator Model	2109AB-10
Number of Anvils	5 (plus 75 mm Sub-Anvil)
Number of Spacers	7
Contact Point Material	Carbide
Physical Weight (kg)	0.95
Dimensions L x W x H (cm)	38.5 x 14 x 5.8

Industrial Applications

1. Large-Engine Cylinder Block Reconditioning

Inspecting the cylinder bores of industrial and marine diesel engines (with bores ranging from 250 mm to 400 mm) for wear, taper, and out-of-roundness (ovality) along the entire piston stroke depth.

Problem Solved

Provides the extreme ±2 µm accuracy required to determine if a cylinder requires oversized pistons, boring, or honing, preventing engine failure due to improper clearances.

Engine Cylinder InspectionTaper MeasurementOvality DetectionCylinder Reboring

2. Heavy-Duty Hydraulic Cylinder Bore Quality Control

Verifying the precise internal diameter limits of massive hydraulic actuators and cylinder barrels used in mining equipment and cranes.

Problem Solved

Ensures the internal barrel maintains a constant bore diameter within a strict 2 µm tolerance. Even small deviations over the 250 mm length could cause high-pressure fluid leakage or seal degradation.

Hydraulic Cylinder BarrelInternal Diameter ToleranceBore GeometrySeal Seat Quality

3. Industrial Gearbox Bearing Housing Inspection

Measuring the bearing seat diameters in large industrial gearboxes and main housings for heavy industrial machinery.

Problem Solved

Ensures bearing bores are perfectly sized to prevent bearing outer rings from spinning or being over-compressed, using the thermal isolation grip to eliminate dimension drift during prolonged metrology cycles.

Bearing Housing InspectionThermal Isolation GripTwo-Point MeasurementIndustrial Gearbox Metrology