Description
Product Overview
The Carl Zeiss Jena 0–25 mm Thread Micrometer is a specialist precision instrument built for direct measurement of screw thread pitch diameters — eliminating the guesswork of three-wire methods and giving you a repeatable, ground-reference reading straight off the thimble. Made in the former East Germany by one of the most respected optical and metrology houses in the world, this is a toolroom-grade piece that belongs on a bench where accuracy is non-negotiable. The set includes a full complement of interchangeable anvil and spindle inserts covering metric and Whitworth thread forms, housed in its original fitted wooden case.
- 0–25 mm measuring range with 0.01 mm graduation — Covers the most commonly encountered thread diameters on the bench, from fine instrument screws through to standard M20 fasteners and Whitworth equivalents. A 0.01 mm (roughly half a thou) graduation means you’re reading pitch diameter directly, not interpolating from a wire calculation — critical when checking threads destined for interference or close-tolerance fits.
- Interchangeable V-anvil and cone-spindle insert system — The set includes multiple insert pairs covering a wide spread of metric pitch ranges (0.4–0.6 mm through to 5–7.5 mm and 7.5–10 mm) and Whitworth TPI ranges (60–48 TPI down to 4.5–3 TPI), as visible on the insert tray. Swapping inserts takes seconds and locks the micrometer into the correct 60° or 55° flank contact geometry for accurate single-wire-equivalent pitch diameter measurement. No separate wires, no arithmetic — just a clean, direct reading.
- Calibrated at 20°C reference temperature — The frame is marked 20°, confirming factory calibration at standard ISO reference temperature. On fine thread work this matters: thermal growth on a steel workpiece and a steel frame tracks together, keeping your readings honest even as the shop heats up through the day.
- Solid C-frame construction with knurled thimble and lock — The hardened and ground anvil and spindle surfaces, combined with a friction-drive thimble and C-spanner lock, give the controlled feel you’d expect from a German toolroom instrument. The spanner wrench included in the case is used to swap inserts and lock the spindle — keep it with the kit.
- Ideal for — Checking pitch diameter on turned and tapped components prior to assembly; verifying thread form on externally threaded bar, studs, and spindles; incoming inspection of fasteners and threaded tooling shanks; toolmaker’s bench work and apprentice training setups where a dedicated thread mic is more reliable than three-wire arithmetic.
Condition
Used (Good Condition / Vintage Toolroom Piece)
The micrometer is in good used condition consistent with a quality instrument that has seen genuine bench service. The C-frame carries the expected patina of age — light surface oxidation and handling marks on the frame exterior — but the critical surfaces are sound. The anvil faces and spindle tip, and the contact faces of the insert set, show no visible pitting or damage that would compromise flank contact geometry. The thimble rotates smoothly with no perceptible backlash or roughness, and the barrel graduations are legible and clean. The locking mechanism functions as intended.
The original fitted wooden case shows wear commensurate with its age — the interior lining has some disturbance and there is crinkled foil/protective material visible in the lid, which is typical of East German instrument cases from this era and does not affect function. Several insert positions in the tray appear occupied and the tray layout is consistent with a full or near-full set; buyers should verify each insert pair against the tray markings (M and W rows visible in the image) upon receipt to confirm completeness of the insert set.
As with any vintage precision instrument, we recommend zeroing the micrometer against a calibrated setting standard or master thread ring before committing it to production measurement. For toolroom or inspection use, a quick verification pass against a known-good thread plug gauge will confirm the instrument is reading true across the range. For hobby shop, teaching, or occasional-use applications, the instrument is ready to put to work straight out of the box.
Included:
- 1 x Carl Zeiss Jena Thread Micrometer, 0–25 mm, 0.01 mm graduation
- 1 x Full interchangeable insert set (metric and Whitworth, housed in original tray — verify count on receipt)
- 1 x C-spanner / insert change wrench
- 1 x Original fitted wooden carry case
Not included:
- Calibration certificate (not supplied — recommend verification against a master before production use)
- Setting standard / thread setting gauge (sold separately if required)
Brand Information
Carl Zeiss Jena is a name that carries genuine weight in precision metrology. Founded in 1846 in Jena, Germany, Zeiss built its reputation on optical and scientific instrumentation to tolerances that defined the benchmark for European precision manufacturing throughout the 20th century. The metrology division — operating under the Jena designation during the East German period — produced measuring instruments that sat firmly alongside Mahr and Mitutoyo in terms of engineering pedigree and material quality, and are still actively sought by toolmakers and collectors who understand the difference between a production instrument and a toolroom instrument. German-made Zeiss metrology is a known quantity on the world market: built to last, engineered without compromise, and still fully serviceable decades after manufacture.
Specifications
| Feature | Specification |
|---|---|
| Brand | Carl Zeiss Jena |
| Type | Thread Micrometer (external pitch diameter) |
| Measuring Range | 0–25 mm |
| Graduation / Resolution | 0.01 mm |
| Reference Temperature | 20°C (ISO standard) |
| Insert System | Interchangeable V-anvil and cone-spindle inserts |
| Metric Insert Range Coverage | Refer to picture (may not be in correct order) |
| Whitworth Insert Range Coverage | Refer to picture (may not be in correct order) |
| Frame Construction | Hardened steel C-frame with knurled thimble and spindle lock |
| Country of Origin | East Germany (Jena, Germany) |
| Condition | Used — Good Condition (vintage toolroom piece; see condition notes) |
| Included Items | Micrometer body, full insert set (M and W), C-spanner, original wooden case |
| Not Included | Calibration certificate, setting standard / thread setting gauge |
Keywords
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