Mitutoyo 511-209 Small Hole Dial Bore Gauge

Technical Overview

High-precision 6-10mm two-point bore gauge with 50mm probe depth, 5µm accuracy, and 2µm repeatability. Features alloy steel anvils and heat-insulating grip.

Key Features

Two-point contact system ideal for detecting internal geometry defects like ovality and taper [1.1.5].
Measuring range of 6 mm to 10 mm with a 50 mm probing depth for deep-set small hole inspections.
Includes a comprehensive 9-piece set of interchangeable alloy steel anvils to cover the full measurement span.
0.5 mm stroke of contact point with a low measuring force of 2 N or less to prevent workpiece deformation.
Hollow-structured, large-diameter grip reduces hand heat transfer by up to 50% to maintain measurement stability.
Standard 8 mm diameter stem compatible with a wide selection of dial and Digimatic indicators.

Technical Specification Matrix

Parameter	Value
Measuring Range	6 - 10 mm
Probing Depth	50 mm
Stroke of Contact Point	0.5 mm
Accuracy	5 µm
Repeatability	2 µm
Adjacent Error	2 µm
Measuring Force	2 N or less
Stem Diameter	8 mm
Number of Anvils	9 pcs
Anvil Material	Alloy Steel
Dial Indicator	Not supplied (Optional)
Heat Shield Grip	Yes (Hollow-structured, 50% heat transfer reduction)
Physical Weight (kg)	0.26
Dimensions L x W x H (cm)	13 x 3.2 x 3.2

Industrial Applications

1. Precision Engine Valve Guide Wear Inspection

Inspecting the interior diameter of small engine valve guides, fuel injector sleeves, and hydraulic cylinder ports. The 6-10 mm measuring range perfectly aligns with common guide sizes.

Problem Solved

Identifies localized ovality and taper wear within a 5 µm tolerance, preventing oil leakage or valve sticking without damaging softer brass or copper guide alloys thanks to the low 2 N measuring force.

6-10mm rangeovality detectiontaper measurementvalve guide inspectionlow measuring force

2. Hydraulic Valve Spool Sleeve Tolerancing

Verifying the internal sliding clearance of hydraulic control valve spool sleeves in aerospace and heavy equipment fluid systems.

Problem Solved

Ensures precise fit clearances for high-pressure spools by delivering repeatable readings to 2 µm inside bores up to 50 mm deep, reducing fluid bypass and hydraulic system pressure drops.

sliding clearances50mm probe depthrepeatabilityfluid power QAtwo-point contact

3. Medical Device Surgical Implant QA

Performing strict quality control on bone screw threads and receiving sleeve components of orthopedic implants in temperature-controlled metrology cleanrooms.

Problem Solved

Eliminates tool thermal expansion errors caused by hand heat during rapid, multi-part manual gauging inspections using the 50% heat-insulating grip technology.

thermal stabilityheat-insulating gripmedical manufacturing QAalloy steel anvilsmetrology lab