Precision Granite Triangle Ruler

Precision Granite Triangle Ruler

The Gold Standard in Angular Reference Instrumentation

A Precision Granite Triangle Ruler is not merely a measurement tool—it is a certified angular artifact engineered to establish,verify,and maintain perpendicularity with uncompromising accuracy.Fabricated from ultra-stable,high-density granite and subjected to rigorous metrological calibration,it serves as the definitive reference for 90°angles in environments where conventional squares cannot meet the demands of modern precision manufacturing,calibration laboratories,and quality assurance systems.

Uncompromising Material&Engineering

Metrology-Grade Granite

Source:Quarries specializing in fine-grained,high-density black granite(≥2.98 g/cm³)

Thermal Properties:Coefficient of thermal expansion 5.0–6.0×10⁻⁶/°C—half that of steel—ensuring dimensional integrity across fluctuating temperatures

Structural Integrity:Free from voids,cracks,or mineral inclusions;each block is ultrasonically screened

Stabilization:Months of natural aging and controlled thermal cycling to release residual stresses

Monolithic Construction

Single-Piece Machining:No laminations or adhesives;entire ruler is ground from one block

Optimized Cross-Section:Thickness-to-length ratio engineered via finite element analysis(FEA)to maximize stiffness while minimizing weight

Hardened Wear Surfaces:Critical edges and faces may receive localized hardening treatments

Surface&Edge Perfection

Flatness:Working faces flat within±0.000025″(0.635µm)over full length

Surface Finish:Lapped to 2–4µin Ra(0.05–0.10µm)—smoother than most gauge blocks

Edge Acuity:Precision-honed edges with consistent radius<0.001″(25µm)for repeatable contact

Geometric Integrity:All faces parallel and perpendicular within≤2 arc-seconds

Accuracy Grades&Specifications

Angular Accuracy:90°±0.5 arc-seconds(±2.5µrad)

Straightness of Edges:±0.000010″/12″(±0.25µm/300 mm)

Calibration Uncertainty:≤0.2 arc-seconds(traceable to NIST/PTB)

Applications:National metrology institutes,primary angle standards,semiconductor fab master tools

Grade AA(Laboratory Standard)

Angular Accuracy:90°±1.0 arc-seconds(±5µrad)

Straightness of Edges:±0.000020″/12″(±0.5µm/300 mm)

Calibration Uncertainty:≤0.5 arc-seconds

Applications:Accredited calibration labs,aerospace/defense first-article inspection,optical manufacturing

Grade A+(High-Precision Inspection)

Angular Accuracy:90°±2.0 arc-seconds(±10µrad)

Straightness of Edges:±0.000040″/12″(±1.0µm/300 mm)

Calibration Uncertainty:≤1.0 arc-second

Applications:Precision machining QC,medical device inspection,automotive PPAP stations

Grade A(General Precision Inspection)

Angular Accuracy:90°±5.0 arc-seconds(±25µrad)

Straightness of Edges:±0.000080″/12″(±2.0µm/300 mm)

Calibration Uncertainty:≤2.0 arc-seconds

Applications:Toolroom reference,production layout,incoming inspection

Advanced Design Features

Ergonomics&Usability

Balanced Weight Distribution:Center of gravity positioned for stable,one-handed use

Non-Slip Gripping Zones:Sandblasted or rubberized areas on non-critical surfaces

Lifting&Handling Provisions:Dedicated slots or recessed handles(for larger sizes)

Thermal Isolation:Optional cork or polymer insulators on handling surfaces

Enhanced Metrology Features

Centerline Markings:Laser-etched fiducials at exact geometric center

Reference Datum Points:Precision divots or tooling balls for CMM probing

Integrated Level Vials:High-precision spirit levels(accuracy 0.02 mm/m)

Modular Attachments:Interfaces for dial indicators,electronic probes,or optical comparators

Specialized Variants

"L"vs."Triangular"Profiles:Traditional L-shape vs.triangular prism for added stiffness

Through-Hole Designs:Central openings reduce weight while maintaining rigidity

Stepped or Tiered Edges:Multiple reference heights in one tool

Magnetic Base Compatible:Incorporates ferrous inserts for secure mounting to magnetic plates

Calibration&Certification

Individual Calibration Process

Laser Autocollimator Measurement:Angular deviation measured at multiple positions

CMM Volumetric Verification:Full 3D characterization of all faces and edges

Interferometric Flatness Mapping:Each face scanned with phase-shifting interferometer

Environmental Compensation:Measurements corrected to standard 20°C reference

Comprehensive Documentation

NIST-Traceable Certificate:Individual serial number with full measurement data

3D Error Map:Graphical representation of angular and straightness deviations

Material Certificate:Density,hardness,and thermal expansion verification

Uncertainty Budget:Detailed analysis of measurement uncertainty contributors

Recalibration Service

On-Site Option:Mobile calibration labs can perform in-situ verification

Historical Trending:Database tracks dimensional stability over decades

Critical Applications

Aerospace&Defense

Airframe Assembly Jigs:Master square for aligning bulkheads and spars

Composite Tooling:Verifying perpendicularity of mold surfaces

Turbine Blade Inspection:Checking root and tip angles on turbine components

Optical System Alignment:Aligning rangefinders,targeting systems,and sensors

Semiconductor&Electronics

Photolithography:Verifying perpendicularity of reticle stages

Wafer Handling Robots:Aligning end-effectors to wafer cassettes

Metrology System Setup:Reference for CD-SEM,AFM,and overlay measurement tools

Cleanroom Compatibility:Non-shedding,chemically inert surface

Precision Optics

Lens Cell Alignment:Ensuring optical axes are perpendicular to mounting surfaces

Prism&Mirror Assembly:Aligning right-angle prisms and corner cubes

Interferometer Setup:Reference flat for optical flat testing

Collimator Alignment:Aligning collimators to optical benches

Automotive(High-End&Motorsport)

Chassis Jigging:Master reference for space frame and monocoque assembly

Suspension Geometry:Setting up alignment rigs and fixture gauges

Engine Building:Verifying block deck squareness to crank centerline

Carbon Fiber Layup:Tooling master for composite parts

Medical Device Manufacturing

Surgical Robot Calibration:Reference for robotic arm perpendicularity

Implant Inspection:Verifying angular tolerances on orthopedic implants

Diagnostic Equipment:Aligning imaging system components(MRI,CT,X-ray)

Cleanroom Assembly:Reference for aseptic assembly workstations