Description
Product Overview
The Mitutoyo Holtest 368-708 is a three-point internal micrometer designed for accurate bore measurement in the 30–35mm range. Unlike a two-point bore gauge that needs a master to set zero, the Holtest’s self-centring three-anvil contact system locates on the bore axis automatically — giving you a direct-reading measurement without chasing the true diameter. That makes it a genuine toolroom instrument for production checking, not just a comparative gauge.
- Three-point self-centring contact system — Three equally-spaced carbide-tipped anvils contact the bore simultaneously, self-aligning to the true centreline. This eliminates the rocking error common to two-point bore gauges and delivers a direct diameter reading without needing to find the minimum swing manually. Critical when you’re checking bores to tight tolerances on a production run.
- 30–35mm measuring range — Covers a highly practical range for bearing housings, hydraulic cylinder bores, bushing fits, and spindle bore checks on smaller lathes and machining centres. The 5mm range within a single head means no anvil swaps mid-job.
- Direct micrometer thimble reading — Readings are taken directly off the barrel and thimble graduation — no dial indicator, no conversion. The 0.001mm (1 micron) graduation keeps you honest when you’re working to H7 or tighter fits. Visible on the thimble in the photograph, the graduations are clearly marked at 30–35 with 0.001mm divisions.
- Compatibility and accessories — The 368-708 is a standalone Holtest head. A Mitutoyo setting ring (sold separately, as noted by the seller) is the recommended method for zeroing — a ring gauge in the nominal bore size gives you a traceable ground reference to set against. Do not attempt to zero against a micrometer anvil or vee-block; use the correct ring.
- Ideal for — Checking bearing housing bores for interference or transition fits, measuring hydraulic and pneumatic cylinder bores, verifying bushing and sleeve fits on a lathe or mill, confirming reamed hole diameters to drawing tolerance, and production spot-checking where a two-point gauge introduces too much operator variability.
Condition
Used (Good Condition / Clean Body, Usable Measuring Faces)
The body of this Holtest presents cleanly — the knurled grip and barrel show the expected patina of a well-kept toolroom instrument, but there are no signs of abuse, impact damage, or corrosion on the critical surfaces. The carbide anvil tips, which are the wear surface that matters most on a Holtest, appear intact and free from chips or flat spots based on the seller’s assessment and the condition of the instrument overall. The thimble rotates smoothly and the ratchet stop functions as intended. As with any used precision instrument, the buyer should verify zero against a certified setting ring in the 30–35mm range before putting this tool into production use — this is standard practice for any Holtest coming off a different bench, regardless of apparent condition. The seller notes that setting rings are available separately, which is the correct way to re-establish a traceable zero on this instrument. Once verified, this Holtest is ready for honest work.
Included
- 1 x Mitutoyo Holtest Three-Point Internal Micrometer, 30–35mm, Model 368-708
- 1 x Original Mitutoyo wooden storage case
- 1 x Operation Manual / Papers
- Original accessories (as supplied with instrument)
Not Included
- Setting ring (required for zeroing — available separately from seller, or source a Mitutoyo or equivalent certified ring gauge in the 30–35mm range)
Brand Information
Mitutoyo is Japan’s largest precision measuring instrument manufacturer and sits at the top tier of the global metrology market alongside Mahr, Tesa, and Starrett. Founded in 1934, Mitutoyo instruments are manufactured to exacting JIS and ISO standards and are the default specification for toolroom and quality assurance environments across aerospace, automotive, and general engineering worldwide. In Australian machine shops, Mitutoyo is the benchmark brand — when someone says “get the Mitutoyo,” they mean the accurate one.
Specifications
| Feature | Specification |
|---|---|
| Brand | Mitutoyo |
| Model | 368-708 |
| Type | Holtest Three-Point Internal Micrometer |
| Series | 368 |
| Measuring Range | 30–35mm |
| Graduation / Resolution | 0.001mm |
| Accuracy | ±0.003mm (per Mitutoyo specification for this series — verify against current datasheet) |
| Contact Points | Three-point self-centring, carbide-tipped anvils |
| Material / Construction | Hardened steel body, carbide measuring faces, knurled grip sleeve |
| Country of Origin | Japan |
| Condition | Used — Good Condition / Clean body, usable measuring faces |
| Included Items | Instrument, original wooden case, operation manual, original accessories |
| Not Included | Setting ring (available separately from seller) |
Keywords
Mitutoyo 368-708, Mitutoyo Holtest, Mitutoyo three-point internal micrometer, bore mic 30-35mm, internal micrometer holtest, Mitutoyo bore gauge, three point bore gauge, holtest micrometer toolroom, internal micrometer machining, bore measurement gauge Australia, precision bore mic, bearing housing bore gauge
