Description
Product Overview
The Mitutoyo 177-271 Setting Ring is a 6.499mm precision ground reference standard used to zero and verify internal measuring instruments. Whether you’re setting a bore gauge, calibrating a small-hole gauge, or verifying an air gauge master, this ring gives you a traceable, stable datum you can trust on the bench or in a quality-controlled toolroom environment. At sub-half-micron nominal size (6.499mm rather than a round 6.5mm), it accounts for instrument offset and wear allowance — the kind of detail that separates a proper metrology standard from a simple go/no-go gauge.
- Precision ground bore to 6.499mm nominal diameter — the non-round nominal value is deliberate: setting rings are sized to allow for gauge wear and instrument offset, meaning your bore gauge or plug gauge is zeroed to a traceable reference, not an assumed round number. This matters when you’re holding a tolerance of a few microns on a production bore.
- Hardened steel construction with a lapped internal bore — the bore surface is the functional surface, and Mitutoyo laps it to a surface finish that won’t introduce cosine or form errors when you’re inserting a gauge head. A rough or out-of-round bore in the setting ring defeats the entire purpose of calibration.
- Compact, low-profile disc form factor — the ring’s geometry makes it easy to handle with one hand and insert a gauge squarely without rocking. For small-diameter settings under 10mm, this is a practical advantage over larger master rings that can be awkward to stabilise.
- Compatibility — designed for use with Mitutoyo and compatible bore gauges, small hole gauges, air gauging masters, and plug gauge verification in the 6–7mm range. No additional adapters required; the ring stands alone as a complete reference standard.
- Ideal for — zeroing telescoping or dial bore gauges before checking valve guide bores, small hydraulic cylinder bores, bearing housing bores, and bush fits; verifying small-diameter plug gauge wear in a toolroom; and establishing a traceable zero reference on a CMM fixture setup.
Condition
New Old Stock (Unused / Original Packaging)
This setting ring presents in genuinely unused condition. The lapped bore shows no contact marks, gauge insertion wear, or surface scratching — the functional surface is clean and unmarked, exactly as it left the Mitutoyo factory. The external faces and OD carry no handling damage or corrosion. The engraved markings — size, model number, serial, and country of origin — are crisp and fully legible. Being NOS, there is no certainty of a current calibration certificate, which is standard for aged stock of this type. For toolroom or quality-assurance applications requiring traceable certification, we recommend having the ring verified against a calibrated reference or submitted for recertification before use in a formal inspection process. For workshop bench use — zeroing a bore gauge before a production run, setting up a small-hole gauge for a fit check — the ring’s unused bore condition means it will perform as intended straight out of the packaging. Stored in its original rubber protective case, the bore has been protected from incidental contact and atmospheric contamination during storage.
Included:
- 1 x Mitutoyo Setting Ring, 6.499mm, No. 177-271
- 1 x Original rubber protective case
- 1 x Original box / packaging
Not included: Calibration certificate (NOS stock — recertification recommended for formal QA applications); bore gauge or measuring instrument (sold separately).
Brand Information
Mitutoyo Corporation, founded in Japan in 1934, is the world’s largest manufacturer of precision measuring instruments and sits at the top tier of global metrology alongside Mahr, Tesa, and Carl Zeiss. Their setting rings, gauge blocks, and reference standards are manufactured to exacting tolerances in dedicated metrology-grade facilities and are accepted as reference-quality tooling in ISO-accredited laboratories, aerospace manufacturing, and high-precision toolrooms worldwide. Japanese country of origin is a direct indicator of manufacturing discipline and material quality control — Mitutoyo’s standards are not rebadged commodity product, and their bore standards are a known quantity on Australian shop floors.
Specifications
| Feature | Specification |
|---|---|
| Brand | Mitutoyo |
| Model / Part Number | No. 177-271 |
| Type | Setting Ring (Internal Reference Standard) |
| Series | 177 |
| Nominal Bore Diameter | 6.499 mm |
| Graduation / Resolution | N/A — fixed reference standard |
| Accuracy / Tolerance | Manufactured to Mitutoyo Series 177 tolerances (sub-micron bore form — refer to current Mitutoyo catalogue for grade tolerance) |
| Material / Construction | Hardened steel, lapped bore |
| Serial Number | 230130 |
| Country of Origin | Japan |
| Condition | New Old Stock (Unused) |
| Included Items | Setting ring, original rubber protective case, original box / packaging |
| Not Included | Calibration certificate; bore gauge / measuring instrument |
Keywords
Mitutoyo 177-271, Mitutoyo setting ring, setting ring 6.499mm, bore gauge setting ring, internal reference standard, Mitutoyo bore standard, toolroom gauge standard, small bore setting ring, precision bore gauge zero, metrology reference ring, bore gauge calibration, Australian machinist measuring tools
