Mitutoyo 329-250-30 Digital Depth Micrometer

Technical Overview

Digital depth micrometer featuring 0-150mm range, 0.001mm resolution, and 6 interchangeable rods with a 101.6mm base and Digimatic SPC data output.

Key Features

Interchangeable lapped rods (Ø4mm) enable wide-range depth measurement from 0 to 150 mm
Precision tool steel base (101.6 x 16 mm) is hardened and micro-lapped for flat, rock-steady reference positioning
Digimatic SPC data output port facilitates automated data logging and statistical process control
Ratchet stop mechanism delivers constant measuring force to ensure operator-independent repeatability
Absolute electromagnetic induction encoder retains origin point to eliminate over-speed errors
Digital LCD with 7.5 mm high digits for quick, error-free readings of measured depth

Technical Specification Matrix

Parameter	Value
Measuring Range	0 - 150 mm
Resolution	0.001 mm
Accuracy	±3 µm (micrometer head feed)
Base Size	101.6 x 16 mm
Number of Rods	6
Rod Diameter	4 mm
Flatness of Base Reference Face	2 µm
Flatness of Measuring Rod Face	0.3 µm
Parallelism Between Reference and Measuring Rod Face	(4 + L/50) µm, where L = max measuring length (mm)
Spindle Pitch	0.5 mm
Measuring Span	25 mm
Zero Point Error of Rods	±4 µm
Power Supply	1x SR44 Button Cell Battery (Part No. 938882)
Battery Life	Approx. 2.4 years under normal use
Data Output	Yes (Digimatic SPC)
Ingress Protection Rating	Non-waterproof
Physical Weight (kg)	0.54
Dimensions L x W x H (cm)	10.16 x 1.6 x 8.48

Industrial Applications

1. Precision Depth Verification of Machined Mold and Die Cavities

In high-precision manufacturing, machined cavities and blind holes in injection molds must match precise specifications. The 329-250-30 depth micrometer with its flat 101.6 mm base spans the cavity openings, allowing inspectors to swap interchangeable rods and measure depths down to 150 mm with ±3 µm accuracy.

Problem Solved

Eliminates reading inaccuracies in deep structural pockets and provides repeatable constant-force measurements via the integrated ratchet stop.

Machining MetrologyBlind Hole DepthMold InspectionInterchangeable RodsRatchet Stop Repeatability

2. Automated Quality Control Data-logging in Automotive Powertrain Assembly

During powertrain component assembly, critical recess clearances must be inspected. Using the Digimatic SPC data output, technicians can perform depth measurements and directly export the numerical results to a PC or SPC database with a single button press via optional U-WAVE transmitters.

Problem Solved

Eliminates manual keyboard-entry errors and significantly accelerates the high-volume data-logging process on assembly lines.

Statistical Process Control (SPC)Digimatic SPC OutputPowertrain Quality AssuranceAutomated Metrology Logging

3. Industrial Pump Shaft Keyway and Recess Wear Inspection

In heavy machinery maintenance, measuring the depth of keyways, pump shaft recesses, and valve seats is critical to identify mechanical wear. The 4 mm thin, micro-lapped measuring rods can reach deep into narrow recesses while the wide base ensures stable bridging over large shaft diameters.

Problem Solved

Enables inspection of narrow shaft keyways that are too tight for standard depth gauges, using a single, versatile tool with zero-point error compensation.

Shaft Keyway WearPump MaintenanceLapped Base StabilityNarrow Recess Measurement