Description
Product Overview
The Mitutoyo 103-138 is a 25–50mm outside micrometer built to toolroom standards — the kind of instrument you reach for when the measurement actually matters. Part of Mitutoyo’s established 103-series, this mic features a 0.01mm graduation on a finely ground thimble and barrel, giving you reliable, repeatable readings across the full 25mm travel. Whether you’re checking turned diameters on the lathe, confirming ground stock before a press fit, or verifying a bore gauge setting, this is the instrument that earns its place on the bench.
- 25–50mm measuring range with 0.01mm graduation — covers the mid-range diameters that come up constantly in general machining and toolmaking. The 0.01mm (roughly half a thou) resolution means you’re reading to a level of precision that actually reflects the capability of a quality centre lathe or surface grinder.
- Carbide-tipped anvil and spindle faces — hardened carbide contact faces resist wear significantly better than plain steel, keeping your measuring surfaces flat and true over years of use. On a mic you’re relying on for press fits or bearing seats, face condition is everything.
- Ratchet stop thimble — the built-in ratchet stop ensures consistent measuring force every time, eliminating operator-to-operator variation and protecting delicate workpiece surfaces from over-pressure. Critical when you’re measuring finished ground diameters or thin-walled components.
- 25mm setting standard included — unlike entry-level mics that ship without a reference gauge, the 103-138 includes a setting standard so you can zero the instrument correctly at the bottom of its range. You can’t zero a 25–50mm mic at zero like a 0–25mm — the setting standard is not optional equipment, it’s how you use the tool correctly.
- Ideal for — checking turned and ground shaft diameters, verifying stock size before milling or grinding, setting bore gauges and telescoping gauges against a known reference, incoming inspection of bar stock and precision components, and toolroom acceptance checks on machined parts.
Condition
(New — Factory Sealed)
This Mitutoyo 103-138 is factory sealed and unused. The instrument has not been removed from its original Mitutoyo case and retains all original factory packaging, including the protective wrapping on the micrometer body. All precision surfaces — the carbide anvil face, spindle face, barrel graduations, and thimble — are in as-manufactured condition with no wear, corrosion, or contact marks. The instrument ships with its original Mitutoyo certificate of inspection, confirming flatness and parallelism of measuring faces and full-surface contact error at multiple points across the range, all measured against Mitutoyo’s own inspection standard traceable to NMIJ/AIST (equivalent to NIST and PTB via CIPM MRA). There are no flaws to disclose. As with any new precision instrument, we recommend zeroing against the included 25mm setting standard before first use and allowing the mic to temperature-stabilise at your working environment (reference temperature 20°C) before taking critical measurements.
Included:
- 1 x Mitutoyo 103-138 Outside Micrometer, 25–50mm, 0.01mm graduation
- 1 x 25mm setting standard (reference gauge)
- 1 x Mitutoyo Certificate of Inspection
- 1 x Spanner wrench (for thimble adjustment)
- Original Mitutoyo fitted case
- Original Mitutoyo product documentation / manual
Not included: Nothing expected is missing — all original accessories and documentation are present.
Brand Information
Mitutoyo Corporation is a Japanese precision instrument manufacturer founded in 1934 and is widely regarded as the global benchmark in dimensional metrology. Their instruments are the standard reference in toolrooms, inspection departments, and calibration laboratories worldwide — sitting at the same tier as Mahr, Tesa, and Starrett, and consistently preferred over Chinese and Taiwanese alternatives in applications where traceability and long-term calibration stability matter. Made in Japan, Mitutoyo instruments are supported by a global calibration and service network, including authorised service and recertification in Australia.
Specifications
| Feature | Specification |
|---|---|
| Brand | Mitutoyo |
| Model | 103-138 |
| Series | 103 Series — Standard Outside Micrometer |
| Type | Outside Micrometer (Mechanical) |
| Measuring Range | 25–50mm |
| Graduation / Resolution | 0.01mm |
| Accuracy | ±2µm (as per certificate of inspection) |
| Reference Temperature | 20°C |
| Anvil / Spindle Faces | Carbide-tipped |
| Thimble Drive | Ratchet stop |
| Frame Material | Cast steel with heat-insulating thimble grip |
| Country of Origin | Japan |
| Inspection Standard | JISB7502 (2016), ISO3611 (2010), DIN863-1 (2017) — traceable to NMIJ/AIST via JCSS |
| Condition | New (Factory Sealed) |
| Included Items | Micrometer, 25mm setting standard, certificate of inspection, spanner wrench, fitted case, documentation |
| Not Included | Nothing — complete as factory supplied |
Keywords
Mitutoyo 103-138, Mitutoyo outside micrometer, Mitutoyo 25-50mm micrometer, outside micrometer 25-50mm, micrometer 0.01mm graduation, toolroom micrometer, precision outside mic, machinist micrometer Australia, shaft diameter measurement, Mitutoyo Japan micrometer, metrology micrometer, micrometer with calibration certificate
