Description
Product Overview
The Mitutoyo 177-146 is a 50mm precision setting ring gauge — a hardened, ground reference standard used to zero and verify bore measuring instruments before they go anywhere near a job. At 50.004mm internal diameter, this ring gives you a certified reference point for setting bore gauges, air gauges, and internal micrometers so your first measurement on the part is one you can actually trust.
- Hardened and precision-ground bore — 50.004mm certified internal diameter: The bore surface is lapped to a mirror finish and held to tight tolerances, giving you a stable, repeatable reference that won’t drift between uses. The 0.004mm offset from nominal is common in Mitutoyo’s setting ring series and is clearly marked — always account for it when zeroing your instrument.
- Robust, thermally stable construction: The ring is manufactured from hardened steel, which resists wear at the reference surface over thousands of setting cycles. Thermal stability matters here — if you’re working in a temperature-controlled toolroom or waiting for parts to stabilise before measuring, a hardened steel ring behaves predictably.
- Protective outer jacket / grip ring: The cream-coloured polymer outer sleeve visible in the image isn’t decorative — it acts as a thermal barrier, slowing heat transfer from your hand to the ring body so skin temperature doesn’t introduce dimensional error during use. It also makes the ring easier to handle without scratching the reference bore on the bench.
- Compatibility: Designed for use with Mitutoyo bore gauges, internal micrometers, air gauging systems, and any other bore-measuring instrument requiring a 50mm setting master. No additional accessories are required to use the ring itself.
- Ideal for: Zeroing two-point or three-point bore gauges before checking cylinder bores, bearing housings, hydraulic block bores, or bush fits; verifying internal micrometre zero on 50mm range instruments; setting air gauging plugs on production lines; and confirming bore gauge repeatability during toolroom calibration routines.
Condition
Used (Good Condition / Toolroom Pulled)
The reference bore is in good functional condition — the lapped internal surface shows no visible scoring, pitting, or damage to the measuring surface. The hardened bore retains its ground finish and is free from the kind of wear or contact marks that would compromise its use as a setting reference. The outer polymer grip sleeve shows age-related discolouration consistent with normal bench use — this is purely cosmetic and has no effect whatsoever on the ring’s dimensional performance. The engraved markings (50.004mm, model number 177-146, serial 040623) are clean and fully legible. As with any used setting master, we recommend verifying the ring against a calibrated reference or CMM before committing it to critical production work, particularly if traceability documentation is required for your QMS. For toolroom, maintenance, or high-quality hobby shop use, this ring is entirely fit for purpose as presented.
Included:
- 1 x Mitutoyo Setting Ring 177-146 — 50.004mm internal diameter
- 1 x Protective carry case / pouch
Not included: Calibration certificate or NATA traceable documentation.
Brand Information
Mitutoyo is Japan’s largest manufacturer of precision measuring instruments and one of the most respected names in metrology worldwide — sitting at the top tier of the market alongside Mahr, Tesa, and Starrett. Founded in 1934 and headquartered in Kawasaki, Japan, Mitutoyo manufactures everything from handheld verniers to coordinate measuring machines, and their toolroom-grade gauging products are used as reference standards in aerospace, automotive, and defence manufacturing globally. Japanese-made Mitutoyo instruments are widely regarded as the benchmark for value, accuracy, and long-term reliability in the Australian toolroom market.
Specifications
| Feature | Specification |
|---|---|
| Brand | Mitutoyo |
| Model / Part Number | 177-146 |
| Type | Setting Ring Gauge |
| Series | 177 Series |
| Internal Diameter (Nominal) | 50mm |
| Actual Certified Bore Diameter | 50.004mm |
| Construction / Material | Hardened steel bore, precision lapped; polymer outer thermal grip sleeve |
| Primary Use | Zero setting and verification of bore gauges, internal micrometers, and air gauges |
| Country of Origin | Japan |
| Serial Number | 040623 |
| Condition | Used — Good Condition |
| Included Items | Setting ring, protective carry case / pouch |
| Not Included | Calibration certificate / NATA traceable documentation |
Keywords
Mitutoyo 177-146, Mitutoyo setting ring, Mitutoyo bore gauge master, 50mm setting ring gauge, bore gauge setting ring, internal bore reference standard, toolroom gauge Australia, setting ring 50mm, bore gauge zeroing tool, precision bore master ring, Mitutoyo metrology tools, bore gauge calibration master
