Description
Product Overview
The SK 40mm Setting Ring is a precision ground bore reference standard used to calibrate and zero internal measuring instruments. Whether you’re setting a bore gauge, checking a plug gauge, or establishing a known internal diameter reference on the bench, this ring gives you a traceable, repeatable datum to work from. At 40mm nominal diameter with a deviation of -0.0001mm from nominal, this is a toolroom-grade reference — not a workshop approximation.
- Precision ground internal bore to 40mm nominal (-0.0001mm deviation) — That sub-micron deviation figure means you’re setting your bore gauge or internal micrometer against a reference that’s accurate well inside one tenth of a thou. Your measurements are only as good as your reference; this ring gives you a solid one.
- Hardened steel construction with knurled OD — The knurled outer diameter isn’t decorative — it prevents the ring rolling off the bench and gives a secure grip when handling with oily hands. The hardened bore resists wear and maintains geometry through repeated use, which is critical for a setting standard that needs to hold its size over time.
- Clearly engraved nominal size and deviation markings — The face is engraved with 呼40 (nominal 40mm) and the actual deviation (-0.0001mm), so there’s no guesswork about what you’re working to. In a busy toolroom where multiple rings might be in circulation, clear marking prevents costly mix-ups.
- Compatibility — Suits any internal bore gauge, three-point bore micrometer, or air gauge calibrated for the 40mm range. No adaptor or accessory required — just clean the bore, present your instrument, and zero off the ring. Pairs with dial bore gauges, Mitutoyo or similar 3-point internal micrometers, and plug gauge setting equipment.
- Ideal for — Zeroing dial bore gauges before measuring cylinder bores, bearing housings, and hydraulic cylinder bores; setting three-point internal micrometers for tight-tolerance shaft and bore fits; verifying bore gauge accuracy on surface grinders and cylindrical grinding setups; and as a go/no-go reference when checking bored-out workpieces on the lathe or mill.
Condition
Used (Good Condition / Previously Used, Stored Correctly)
The bore — the only surface that actually matters on a setting ring — presents well. The internal diameter shows no visible damage, scoring, or raised burrs that would compromise the reference surface. The flat faces and knurled OD carry the typical light patina and minor surface marks consistent with a used toolroom gauge that’s been handled and stored over time; there is some surface oxidation and light staining visible on the flat face as shown in the photographs, but this is cosmetic only and does not affect the precision ground bore. The ring has been lubricated and wrapped in plastic for storage and shipping — correct practice for preserving a ground bore standard. As with any used setting ring, best practice before putting it into service is to verify the internal diameter against a calibrated internal micrometer or reference gauge at your site; the engraved deviation (-0.0001mm) reflects the original factory calibration and should be treated as a reference point pending your own verification. There is no case included, however the ring is supplied clean, lubricated, and wrapped for transit.
Included:
- 1 x SK 40mm Setting Ring (nominal 40mm, deviation -0.0001mm)
Not included:
- Storage / presentation case
- Calibration certificate
Brand Information
SK (Soko Measuring Instruments) is a well-regarded Japanese metrology brand with a long history of producing hardened and ground gauging tools for toolroom and production environments. Made in Japan, SK products sit comfortably alongside RSK and Niigata as respected mid-to-upper tier Japanese gauge manufacturers — a tier below Mitutoyo in terms of global distribution, but entirely comparable in terms of ground surface quality and dimensional accuracy for setting rings and reference standards. Japanese-made gauging tools carry a strong reputation in Australian toolrooms for consistent quality and long service life, and the “Made in Japan” mark on this ring is a meaningful indicator of manufacturing standard.
Specifications
| Feature | Specification |
|---|---|
| Brand | SK (Soko Measuring Instruments) |
| Type | Setting Ring / Reference Ring Gauge |
| Nominal Bore Diameter | 40mm |
| Actual Deviation from Nominal | -0.0001mm (engraved on face) |
| OD Style | Knurled outer diameter |
| Material / Construction | Hardened steel, precision ground bore |
| Markings | 呼40 (Nominal 40), deviation -0.0001mm, serial/batch L0903 |
| Country of Origin | Japan |
| Condition | Used — Good Condition. Bore surface intact. Cosmetic marks on flat face and OD. Lubricated and wrapped for storage/shipping. |
| Included Items | 1 x SK 40mm Setting Ring |
| Not Included | Storage case, calibration certificate |
Keywords
SK setting ring, SK 40mm ring gauge, SK bore gauge setting ring, setting ring 40mm, internal bore reference standard, ring gauge toolroom, bore gauge zeroing ring, precision ground ring gauge, Japanese ring gauge, bore micrometer setting standard, internal gauge calibration ring, toolroom metrology Australia
