Mitutoyo 511-203-20 Dial Bore Gauge

Technical Overview

Analog 2-point bore gauge covering 10-18.5mm range with 0.001mm resolution and 100mm depth. Features self-centering bridge and thermal-isolated hollow grip.

Key Features

A long plunger stroke provides exceptional measurement accuracy and stability.
Interchangeable 0.5 mm thick washers are supplied as standard to enable setting in small increments.
Anvils are constructed from high-grade alloy steel for outstanding durability and resistance to deformation.
A large, hollow-structured grip reduces thermal transfer from the operator's hand by 50% to maintain measurement integrity.
A self-centering bridge automatically aligns the gauge inside the bore for fast, error-free measuring.
Includes a rugged protective cover (21DZA000) to shield the dial indicator from impact on the workshop floor.

Technical Specification Matrix

Parameter	Value
Measuring Range	10 - 18.5 mm
Graduation	0.001 mm
Accuracy	5 µm
Repeatability	2 µm
Adjacent Error	2 µm
Measuring Depth	100 mm
Stroke of Contact Point	0.6 mm
Measuring Force	2 N or less
Number of Anvils	9
Number of Spacers	1 (0.5 mm)
Dial Indicator Model	2109AB-10
Bore Gauge Rod Model	511-201
Dial Protection Cover Model	21DZA000
Anvil Material	Alloy Steel
Physical Weight (kg)	0.27
Dimensions L x W x H (cm)	24 x 5.7 x 3.5

Industrial Applications

1. Automotive Engine Block Cylinder Rebuilding

Checking internal bore dimensions of small engine cylinder sleeves, valve guides, and small-bore cylinder blocks. The 10–18.5 mm range is ideal for precise measurement of motorcycle, UAV, or marine engine cylinders.

Problem Solved

Detects wear-induced geometry problems like ovality, taper, or out-of-roundness up to 100 mm depth with 0.001 mm resolution, ensuring proper piston clearance and ring seating to avoid compression loss.

Cylinder OvalityTaper DetectionBore GeometryEngine Rebuilding

2. Hydraulic Valve Spool Bore Inspection

Quality assurance of small-bore hydraulic valve blocks and spool guides. High precision is crucial in fluid power systems to prevent internal leakage.

Problem Solved

Ensures the bore meets tight clearance tolerances (within microns) using the 5 µm accuracy and 2 µm repeatability of the gauge, avoiding pressure drops and stick-slip phenomena in high-pressure hydraulic manifolds.

Hydraulic Valve ManifoldsClearance ToleranceSpool Bore AlignmentMicron Accuracy

3. Aerospace Precision Bushing and Bearing Seat Metrology

Verification of internal diameters of critical press-fit bushings and bearing housings in aerospace landing gear and actuator assemblies.

Problem Solved

Eliminates the risk of gauge thermal expansion errors caused by hand heat transfer during long inspections, using the 50% thermal-isolated hollow grip design, securing exact dimensional compliance.

Press-fit BushingBearing Housing SeatsThermal IsolationAerospace Metrology